@2017 American Eagle Foundation. All rights reserved. (www.eagles.org)
(Photo used with permission)
(Photo used with permission)
In Spotlight: Bald Eagle - A Success Story
"In the end, we will conserve only what we love; we will love only what we understand and we will understand only what we are taught."
Baba Dioum, Conservationist, Senegal.
Excerpt from his IUCN speech, 1968
Baba Dioum, Conservationist, Senegal.
Excerpt from his IUCN speech, 1968
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This edition of Wildlife in Spotlight features the Bald Eagle: A Success Story! We trace the remarkable recovery of the national bird of the United States from the brink of extinction to healthy numbers. We do so in an interview with Dr. Bob Sargent who heads the bald eagle management program for the Georgia Department of Natural Resources. It is a fascinating interview in which he touches upon the timeline of the recovery of the species, measures implemented for the recovery along with many interesting facts. I would like to thank Dr. Sargent for making time for the interview and for sharing this truly inspiring story with us!The interview has been formatted in the following order:
• Introduction: Interesting facts about the bald eagle and web links to live nest cams. • Conservation: Threats that decimated the bald eagle population, timeline of policy implementation, and recovery of species. • Ongoing concerns and recovery plan. Please scroll down to read the full transcript of the interview with Dr. Sargent. Mr. Pete Griffin who is mentioned in this interview is the training and development specialist and outreach coordinator for the Charlie Elliott Wildlife Center in Mansfield, GA. I first met him during a presentation on bald eagles at the Endangered Species Day at the Atlanta Botanical Gardens over the summer. |
Dr. Bob Sargent
Biologist
Ayesha Siraj
Interviewer
September 18, 2017
Biologist
Ayesha Siraj
Interviewer
September 18, 2017
Introduction: Interesting facts about the bald eagle and web links to live nest cams
Ayesha: Dr. Sargent, thank you so much for your time. I really appreciate it.
Dr. Sargent: You are welcome.
Ayesha: Let me get started by asking you how long have you been doing this and how did you get involved?
Dr. Sargent: I have been with the Georgia Department of Natural Resources just under two years and prior to that, I worked as a wildlife biologist with the Air Force for 20 years. Research on bald eagles is something relatively new in my career. I have had the opportunity to work with a lot of other fascinating wildlife species. The previous person in this position retired two years ago and he was the state’s eagle biologist for 25 years. In filling this position one of my duties was to inherit the bald eagle work, which has been a real treat. My background is in ornithology and I've done a lot of work with birds but it has mostly been songbird species. So, this is a little bit bigger. But it has been great fun! How cool is that to get to work with bald eagles as part of your job?
Ayesha: Very cool indeed!
Ayesha: As a researcher your probably get a lot of requests to share interesting facts on the bald eagle. I think it might be fun for our young readers to learn about them too. To start, can you elaborate on some key facts such as how high bald eagles fly and their wingspan?
Dr. Sargent: Sure. Their wingspan can be up to 7 -7 1/2 feet. During their day-to-day activities they usually fly at altitudes of less than 300 feet, but they have been observed flying as high as 10,000 feet during migration.
Ayesha: Given that they fly at those heights, how close do they have to be to their prey to be able to spot it or is their vision highly evolved to spot prey from just about any height?
Dr. Sargent: Their eyes are almost as large as ours, and their vision is about four times more powerful than ours. This means they can see objects that are four times farther away than people can. Some researchers have written that eagles might be able to spot other eagles that are 15-20 miles away.
Ayesha: What is the lifespan of a bald eagle?
Dr. Sargent: There are records of eagles in captivity living into their late 30s. But in the wild probably just a small percentage of them live into their teens. It is pretty tough to live long enough to become an adult and to produce young of your own. It is not unusual for the young of bird species or wildlife in general to have a high mortality rate. Various people who have studied them have reported that perhaps 20-30% of them reach adulthood. It takes bald eagles about five years to reach reproductive maturity.
So that pure white head and that white tail really doesn't appear until about age 4. For the first three years of their lives they feature a mottled combination of white and brown feathers. This throws people. It's surprising and so they are often mistaken for other bird species like golden eagles. In fact, in their first year the only white you might see on them is in their wing pits, the joint between the wings and the breast; otherwise, the bird looks all brown. When they are adults they not only have the distinctive white head and white tails but they have those beautiful yellow irises and the yellow bills. But as first and second years birds they don’t. The irises are brown and the bills are gray-brown. Right about year three, you start to see a lot of white appearing in their heads and white patches in the tails. And the bills and irises also start to change color.
Ayesha: When eaglets leave the nest how big are they and how long does it take for them to be as large as their parents?
Dr. Sargent: I get this question a lot. The answer is when they leave the nest they are already as large as their parents. Their wingspan is even bigger than that of their parents when they first fledge. When they go through their first molt cycle their next flight feathers are a little bit shorter and more equivalent to the parents. Amazingly enough, at about nine or ten weeks of age they are already 90-95% the size of the parents.
Ayesha: At Mr. Griffin's presentation, there was a question about their feathers. I didn’t quite hear it but maybe the question was - what if an eagle lost some of its critical flight feathers? What happens next?
Dr. Sargent: Bald eagles molt every year after their hatch year. But the molt is prolonged and it can take up to a few months for them to completely molt their old flight feathers and get brand new feathers. The reason is that if they molted all their flight feathers at once they would have a flightless period, not be able to feed themselves, and so they would starve to death. Oftentimes when feathers are found it is because of a recent molt and not necessarily because of an injury. In other words, if they lose flight feathers it might not necessarily be particularly concerning because the molt might be coming up and they're going to replace those feathers.
Ayesha: How much does an adult bald eagle weigh?
Dr. Sargent: As large as they are they only weigh 9-13 pounds. Their skeletons weigh half as much as their feathers.
Like all birds, they have extremely strong bones and yet most of the bones are hollow. This is because they need to minimize their weight. If you're a bird you have fewer bones than mammals, you have many bones that are fused, you have hollow bones with struts inside them for reinforcement. You don't have a jawbone. You have a bill, which is much lighter in weight than jawbones, and you don't have teeth. Outside of the breeding season your reproductive organs actually shrink. These things are done to minimize weight. People generally assume that large birds such as eagles weigh a lot more than they actually do.
Ayesha: True, that’s what I thought. The bald eagle that I saw at Mr. Griffin’s presentation was huge. So I thought it weighed around 30-35 pounds. Now that you point it out, it makes sense; birds have to minimize their weight.
Ayesha: Are there any differences in appearances between the male and female bald eagle?
Dr. Sargent: What's interesting about eagles and nearly all birds of prey for that matter is that the females are much bigger than the males, maybe 25- 28% bigger than the males. So when you see a mated pair standing in the nest you can tell the sexes apart even though on the surface they look the same just like mockingbirds look the same.
Ayesha: Do bald eagles mate for life?
Dr. Sargent: As far as we know they do mate for life. But that doesn't mean they stay together all year round. They'll stay together for at least six months of the year during nest maintenance, during their mating rituals, when they are laying eggs and brooding young, and then teaching the fledglings the ropes, so-to-speak. But outside of that they will often separate for the remaining months of the year until the next breeding season. This is especially true in the northern United States where in fall or the early winter months the lakes where they get their food freeze over. So what are they going to do? They can’t stick around or they’ll starve. They have to migrate. And it turns out that mated pairs do not necessarily migrate together. We don't know for sure if they actually meet up on their wintering ground. So they may not see each other again until the following spring when nesting activity begins all over again.
Ayesha: What are some of the mating rituals?
Dr. Sargent: Their mating ritual may involve a cartwheel display. Everybody has probably seen the famous cartwheel interaction on television or the internet. This is when the eagles lock talons and seem to fall out of the sky as they spin. Of course that's one of the most spectacular things that you see with the bald eagles. The mating rituals can also involve a roller coaster flight with one chasing the other. They go up to very high altitudes and swoop down and go back up again.
Ayesha: What is the breeding season for bald eagles in Georgia?
Dr. Sargent: The breeding season in Georgia runs from November or early December through early May. Usually we start seeing the first eggs being laid around the December timeframe. Just a few of them lay eggs in December. The majority of them are laying their eggs from January to March and there is a big difference between the timing of the nesting cycle in southern Georgia versus the nesting cycle in northern Georgia. Eagles in the southern part of Georgia have maybe a month to six weeks head start on nesting compared to those in the northern part of the state. We will see young standing in some nests in southern Georgia in late January or early February, whereas in northern Georgia we’re still seeing eggs in some nests at the beginning of March.
Ayesha: So the difference is because of the temperature? Is it?
Dr. Sargent: Sure, and how temperature and rainfall patterns affect the availability of food, especially fish.
Ayesha: What is the difference in the nesting cycle between the southern states versus the northern states in the United States?
Dr. Sargent: Here's another one of those neat things about eagles. While pairs are nesting in Georgia in January, somewhere nearby are eagles waiting to return to their nest sites in Michigan where they will nest in April or the beginning of May. There is at least a 3-3 1/2 month difference in the cycle between eagles nesting in the northern United States versus those in the southern United States.
It's quite an investment if you're a bald eagle pair. To do the work of sprucing up the nest that you've been using for years. To go through the mating ritual, lay the eggs, the incubation and brooding, the fledgling period, and then the eaglets may stick around the neighborhood with their parents for 1 to 3 months. When you add it all up it's a six-month investment for a pair of adult eagles. It’s an extraordinary investment in terms of energy required in rearing young and, of course, there's no guarantee that they'll be successful.
Ayesha: Given that the bald eagle is an apex predator and they do not have a natural predator of their own, what really impacts the successful raising of the hatchlings?
Dr. Sargent: They are at the top of the food chain, but nevertheless there are wildlife hazards for them out there. We have found that great horned owls can sometimes drive eagles off their nests and can certainly take young eagles from nests. Of course it also depends on how diligent the parents are in looking after the nest. Sometimes the eggs and the young can be taken by animals as small as raccoons. Even crows can raid a nest and damage the eggs. And when bald eagle young leave the nest, when they first fledge, like most bird species they are not good at flying. In fact, research shows that 40 to 50% of just fledged eagles crash on their first flight. Sometimes they are injured and in many cases they end up on the ground where they continue to be fed by their parents. When they are on the ground, hiding in shrubbery, they are at the mercy of other predators like bobcats and coyotes. So, even though these are large birds they do sometimes become victims of predation by other species of wildlife.
Ayesha: You've given us an overview of the breeding season, time commitment for a pair of eagles to raise their young, some of the risks the eaglets face during their nest life. Can you tell us a little bit about the incubation and the nest life of the eaglets?
Dr. Sargent: They hatch right around 33 - 35 days and then you're looking at 12 and sometimes 14 weeks before the young fledge the nest. When we visit the nest we can tell how old they are by their size, by the feather development, whether they are standing [or not]. For the first four weeks they are mostly just lying on their bellies. They've got these great big feet the size of the parents’ feet when they are four weeks of age and yet they're not good at standing up. They are very clumsy. They look like a blob with a big bill and big talons. By the age of 9 or 10 weeks you'll start to see them flap their wings. They start jumping up and down in the nest, it's pretty funny to watch. They'll jump and hover for five or six seconds and drop right back into the nest. But sometimes it goes badly for them. They'll start flapping those wings, they'll get airborne and they lift themselves about 3 feet off the nest and a gust of wind blows at the wrong time and blows them right out of the nest. They might cling to a branch somewhere or they may end up tumbling and bouncing from branch to branch. I've seen them do that.
At 12 -13 weeks of age they take their first flight. For the gliding part all they have got to do is hold out their wings - those wings are so large and have so much surface area that they naturally get a lift just like an aircraft’s wings. It's the landing part that gets them. I have seen them leave the nest and go on that first glide. You see them go and you can’t help but wonder if they are thinking, “Oh boy, how am I going to make this happen?” And here comes a tree and they start to lower their feet and they miss-time it, miss the branch they’ve selected, and they actually somersault their way to the ground.
Ayesha: Do bald eagles establish a territory like a lion or a tiger does?
Dr. Sargent: They establish a territory that is centered on the nest and maybe features a radius of one-quarter of a mile around that nest. Sometimes their territory is much smaller, especially if the density- number of pairs of eagles in an area -- is especially high and there is enough food to go around. So if you visit some place like Chesapeake Bay where there's a really high density of bald eagles because there's such a large amount of food and lots of potential nesting sites, then nest territories are smaller. But if the food resources are not especially abundant then the nest territory they defend tends to be larger.
Ayesha: It is my understanding that bald eagles use the same nest over and over again. Is that accurate?
Dr. Sargent: They do. There are some fascinating records of some nests in the country being used for 30-40 years. That's by different generations of eagles, of course, because as I said they don't normally live that long in the wild. One nest that I'm thinking of in the Great Lakes region, I think it was Ohio, was used for over 40 years before the top of the tree failed and the nest fell out of it. There was a nest in the panhandle of Florida that was recorded as weighing nearly 3000 pounds. I believe it was 18 feet tall and about 6 feet wide. That happened because they added new material to the same nest year after year. If you’ve got a great home and you were successful in raising kids last year then why buy a new home? Right? Why go through the trouble of building another one? You show up. There is your mate you haven't seen in five months. Hi, how are you doing? Let's get to work. So they go to their old nest site and it's in pretty good shape. They add more materials to it. Each of them will fly in with branches that they’ve often just broken off from a tree while in flight and not necessarily picked up from the ground. Often times the male will put the materials in the nest and the female will seem to say, “OK, I got it from here, get out of my way,” and she starts fixing things. But they both play a role in sprucing up the nest. Interestingly they will often add a green sprig – a live twig or branch of pine to the nest and we really don't know why. Maybe this is just part of the mating ritual.
Ayesha: That would be interesting to know what exactly that green sprig of branch really means? Could it mean we're getting close to being done sprucing the nest and we're ready to start nesting?
Dr. Sargent: It sure could.
Ayesha: So what exactly do they use besides branches to build their nest? If they're using only branches are they pretty closely knit to ensure that the eggs don't slip out of them?
Dr. Sargent: So the foundation of the nest is large branches with little branches interlocking. It looks like a massive wicker basket. But then in the center they include moss and grasses creating a soft landing space with a little bit of depression and that's where the eggs are found. In the southern parts of the state where Spanish moss is common that's what I'll see in the nest. When the young are about 3 to 4 weeks of age they develop this plumage that we call "thermal down". It looks like gray fuzz and often times it is difficult to see the young because the Spanish moss and the chicks are the same color!
In northern Canada and Alaska where there are no trees eagles nest on cliff faces and sometimes on the ground.
Ayesha: What is the primary diet of a bald eagle?
Dr. Sargent: The vast majority of their food is fish but like all wildlife species there are times when they'll eat something else because other choices become more seasonally abundant. In Georgia probably 70% of their food is fish, but in the winter months they may eat less fish because there are ducks and a bird species called coot that can gather on lakes in large numbers. It is easier to hunt those birds sometimes than it is to catch fish. They eat a number of other things. I have walked around eagle nests and looked at the pieces of critters on the ground. We find a lot of turtle shells. They capture turtles and eat the soft parts. They eat snakes on occasion, and small animals when they can catch them, and other water birds such as ibis. Bald eagles don't hesitate to steal food from other birds. Ben Franklin gave them a bad rap. Franklin famously said that he would rather that the wild turkey was chosen as America’s national symbol. He said that in his opinion the bald eagle had bad moral character because they stole food from ospreys. And they do steal from them!
People assign human emotions to the behavior of a wild animal. It's not like human behavior at all. It has nothing to do with morality. If an eagle can steal food easier than it can capture a meal, then there is no good or bad in it. This is the way they evolved to make a living, so that's what they do.
Ayesha: It’s interesting that you mention that when you walked around under the nest you saw pieces of critters. Given their diet how do the parents keep the nest clean? It must be very messy to have pieces of decomposing critters lying around. How do you keep your nestlings from being totally covered in bacteria?
Dr. Sargent: Late in the nesting season the nest does get pretty smelly, but of course eagles like most birds do not have good senses of smell. You will see all kinds of parts from previous breakfasts and dinners sticking up out of the nest. Fish bones over here, a tail and maybe a leg from a squirrel.
That also is probably part of the motivation for adding new material to the nest the following season. Of course, they have about 6 to 8 months for the nest to air out. And during this time beetles, ants and other creatures eat what wasn't eaten by the young eagles. Mind you they're pretty good about getting every morsel that is brought to their nest. And a lot of the larger parts like bones and hide do end up getting dumped over the side.
Ayesha: Do they make a conscious effort of actually dumping these things off the nest or does it just fall through the crevices?
Dr. Sargent: Some of it actually gets consciously dumped over the side, I think. But a lot of it ends up getting wedged in the branches of the nest itself.
Ayesha: I have very little experience with birds. In fact my only experience is with the robins that have nested in our backyard. What I have noticed with them is that they have this incredible mechanism - so the parents would bring food and as soon as the chicks are fed the chicks have a bowel movement and it is like a little white capsule or pellet that the chicks pass as droppings which then gets carried away by the parents ensuring that the nest stays absolutely clean during their two week nest life. Is that common for bald eagles to?
Dr. Sargent: Did Pete not talk about it in his presentation?
Ayesha: Yes Mr. Griffin did mention that during his presentation that bald eagles have projectile ...
Dr. Sargent: Projectile pooping!!
One of the things that kids get fascinated about is when they hear about projectile pooping - adult birds do it and the young birds, once they are up and walking about the nest, do it. They will pivot so their bottoms are facing outwards from the nest center and they will project their poop. The adults can squirt a stream that can fly up to 30 feet through the air.
Ayesha: From what I remember from Mr. Griffin's presentation was that the droppings are liquid.
Dr. Sargent: Yeah, they are. The white part of bird droppings is actually urine. That’s true even when birds leave behind a small pile of what looks like chalk or solid paste. The green part within the white is the poop.
Ayesha: So why is it liquid and not solid given that their diet includes solid foods?
Dr. Sargent: Bald eagles like other birds of prey regurgitate. They cough up pellets so they don't digest everything.
Birds like owls will swallow their prey whole and later regurgitate a pellet. It looks kind a like an eggroll that has a furry outside instead of a battered outside to it. That pellet contains bones and teeth. It is extremely difficult to digest the really hard parts, and the hard parts could puncture their intestines.
Eagles usually don't swallow their prey whole. When the adults bring food to the nest or capture food for themselves they strip off pieces of meat from an animal carcass. Like owls, they also regurgitate pellets. So you can find pallets around the nest.
Ayesha: I would like to talk a little bit about the cameras that are installed in the eagle nests. Were the nest cams installed primarily to help researchers to understand the behavior of the eagle? Or did they have a dual purpose of being a research tools and creating a relatability factor for the average citizen who might not see a bald eagle on a regular basis?
Dr. Sargent: The cameras have become this wonderful public education tool, haven’t they? In the early days they were used to help us learn more about bird behavior in nests. We wanted to learn more specifics about what they were eating and what they were feeding their young. This is still an important research tool, but nest cams have really developed into a powerful education tool.
Some researchers use nest cams to keep tabs on the nest sites that they cannot visit regularly and so they can download that information. My guess is that the majority of the nest cameras in use now are mostly set up for public education. We are visual creatures and we consume information through all sorts of social media. So naturally we are utilizing this tool for public education.
One of the things that concerns everybody in my profession is that there is a greater and greater disconnect between people and nature. So the nest cam is a great tool in that it brings scenes from nature into people’s homes so they can connect with and understand what's going on out there. But the flipside to that is maybe that experience completely substitutes for actually going out and witnessing nature first hand. I see this a lot when I talk to young people. Kids have access to so much information that I did not have when I was their age. Young people can explain the ins and outs of climate change and holes in the ozone and acidification of the oceans. But they rarely have first-hand experience with wildlife, with understanding the seasons in the life of a wild bird like an eagle, what they're doing at various times of the year, where they are found in the state; things like that. Many people in my generation grew up in the country, often on farms, and so we were immersed in nature every day. So that has changed a lot. I think the [nest] cams have filled that void in that they are providing an educational resource that helps for so many young people who don't spend much time in the outdoors or maybe don't have the opportunity to spend time in the outdoors.
We have two eagle cams in the state right now. The one on Skidaway Island has become an osprey cam because the eagles have not used that nest in the last three seasons. The most well-known one is at Berry College, which is immensely popular and is linked to the Wildlife Resource Division’s website. The pair of eagles there are already fixing up the nest. Here we are in September and they're already doing housekeeping for the next nesting season.
But there are downsides to these nest cams. First of all, logistically it is very difficult to set one up. And secondly, you don't want to do it in a way that actually discourages birds from using the nest or influences the nesting outcome because the camera spooks them.
Another consideration is that sometimes the birds will bring things to the nest that can be disturbing to people who have not been exposed to wildlife behavior. And sometimes young birds die in the nest. Bald eagle young are very aggressive with each other. They don’t all hatch on the same day, because the eggs in the nest – usually two but sometimes three – are not laid on the same day. A female may lay an egg and maybe wait two days before she lays another one. But she starts incubating pretty quickly after that first egg is laid. This is what we called asynchronous hatching. So what happens is the youngest eaglet in the nest is smaller than the older ones. The oldest is stronger and more aggressive about getting food and sometimes the younger one doesn't get enough food and occasionally it starves. It gets weak and the older ones will start picking on it; that's nature. But some people want you to jump in and do something about it. We explain that we let nature take its course. Sometimes nature presents us with some sad scenes.
There are a lot of people who are avid nest cam watchers. I know this because they call and they will say, “So I'm monitoring this nest at a certain location.” Then they say, “I'm really concerned about the second eaglet because it hasn't been fed for quite some time. Can you do something, can you bring food to it?” We should not interfere in these bird’s activities, even when it doesn't work out.
Ayesha: I had heard something similar about an osprey nest on NPR.
Dr. Sargent: Yeah, it was last year that there was a video taken at an osprey nest on Audubon’s Hog Island in Maine.
Eagles raided that osprey nest, attacking the chicks. There were three osprey chicks, almost fully grown, standing in the nest. They were pretty big. And in the distance suddenly materialize two adult eagles flying below the nest. As they climb one of the osprey chicks sees them and goes, “I'm not sticking around for this” and jumps out of the nest. Another one hunches down and lays flat. And the third one is like, “Should I stay or should I go?” and one of the eagles grabs it. I saw comments about it online about what people called “those evil eagles.” No, this is how they make a living. It's not good or bad. This is what they have to do to survive, and it can be shocking sometimes.
Dr. Sargent: You are welcome.
Ayesha: Let me get started by asking you how long have you been doing this and how did you get involved?
Dr. Sargent: I have been with the Georgia Department of Natural Resources just under two years and prior to that, I worked as a wildlife biologist with the Air Force for 20 years. Research on bald eagles is something relatively new in my career. I have had the opportunity to work with a lot of other fascinating wildlife species. The previous person in this position retired two years ago and he was the state’s eagle biologist for 25 years. In filling this position one of my duties was to inherit the bald eagle work, which has been a real treat. My background is in ornithology and I've done a lot of work with birds but it has mostly been songbird species. So, this is a little bit bigger. But it has been great fun! How cool is that to get to work with bald eagles as part of your job?
Ayesha: Very cool indeed!
Ayesha: As a researcher your probably get a lot of requests to share interesting facts on the bald eagle. I think it might be fun for our young readers to learn about them too. To start, can you elaborate on some key facts such as how high bald eagles fly and their wingspan?
Dr. Sargent: Sure. Their wingspan can be up to 7 -7 1/2 feet. During their day-to-day activities they usually fly at altitudes of less than 300 feet, but they have been observed flying as high as 10,000 feet during migration.
Ayesha: Given that they fly at those heights, how close do they have to be to their prey to be able to spot it or is their vision highly evolved to spot prey from just about any height?
Dr. Sargent: Their eyes are almost as large as ours, and their vision is about four times more powerful than ours. This means they can see objects that are four times farther away than people can. Some researchers have written that eagles might be able to spot other eagles that are 15-20 miles away.
Ayesha: What is the lifespan of a bald eagle?
Dr. Sargent: There are records of eagles in captivity living into their late 30s. But in the wild probably just a small percentage of them live into their teens. It is pretty tough to live long enough to become an adult and to produce young of your own. It is not unusual for the young of bird species or wildlife in general to have a high mortality rate. Various people who have studied them have reported that perhaps 20-30% of them reach adulthood. It takes bald eagles about five years to reach reproductive maturity.
So that pure white head and that white tail really doesn't appear until about age 4. For the first three years of their lives they feature a mottled combination of white and brown feathers. This throws people. It's surprising and so they are often mistaken for other bird species like golden eagles. In fact, in their first year the only white you might see on them is in their wing pits, the joint between the wings and the breast; otherwise, the bird looks all brown. When they are adults they not only have the distinctive white head and white tails but they have those beautiful yellow irises and the yellow bills. But as first and second years birds they don’t. The irises are brown and the bills are gray-brown. Right about year three, you start to see a lot of white appearing in their heads and white patches in the tails. And the bills and irises also start to change color.
Ayesha: When eaglets leave the nest how big are they and how long does it take for them to be as large as their parents?
Dr. Sargent: I get this question a lot. The answer is when they leave the nest they are already as large as their parents. Their wingspan is even bigger than that of their parents when they first fledge. When they go through their first molt cycle their next flight feathers are a little bit shorter and more equivalent to the parents. Amazingly enough, at about nine or ten weeks of age they are already 90-95% the size of the parents.
Ayesha: At Mr. Griffin's presentation, there was a question about their feathers. I didn’t quite hear it but maybe the question was - what if an eagle lost some of its critical flight feathers? What happens next?
Dr. Sargent: Bald eagles molt every year after their hatch year. But the molt is prolonged and it can take up to a few months for them to completely molt their old flight feathers and get brand new feathers. The reason is that if they molted all their flight feathers at once they would have a flightless period, not be able to feed themselves, and so they would starve to death. Oftentimes when feathers are found it is because of a recent molt and not necessarily because of an injury. In other words, if they lose flight feathers it might not necessarily be particularly concerning because the molt might be coming up and they're going to replace those feathers.
Ayesha: How much does an adult bald eagle weigh?
Dr. Sargent: As large as they are they only weigh 9-13 pounds. Their skeletons weigh half as much as their feathers.
Like all birds, they have extremely strong bones and yet most of the bones are hollow. This is because they need to minimize their weight. If you're a bird you have fewer bones than mammals, you have many bones that are fused, you have hollow bones with struts inside them for reinforcement. You don't have a jawbone. You have a bill, which is much lighter in weight than jawbones, and you don't have teeth. Outside of the breeding season your reproductive organs actually shrink. These things are done to minimize weight. People generally assume that large birds such as eagles weigh a lot more than they actually do.
Ayesha: True, that’s what I thought. The bald eagle that I saw at Mr. Griffin’s presentation was huge. So I thought it weighed around 30-35 pounds. Now that you point it out, it makes sense; birds have to minimize their weight.
Ayesha: Are there any differences in appearances between the male and female bald eagle?
Dr. Sargent: What's interesting about eagles and nearly all birds of prey for that matter is that the females are much bigger than the males, maybe 25- 28% bigger than the males. So when you see a mated pair standing in the nest you can tell the sexes apart even though on the surface they look the same just like mockingbirds look the same.
Ayesha: Do bald eagles mate for life?
Dr. Sargent: As far as we know they do mate for life. But that doesn't mean they stay together all year round. They'll stay together for at least six months of the year during nest maintenance, during their mating rituals, when they are laying eggs and brooding young, and then teaching the fledglings the ropes, so-to-speak. But outside of that they will often separate for the remaining months of the year until the next breeding season. This is especially true in the northern United States where in fall or the early winter months the lakes where they get their food freeze over. So what are they going to do? They can’t stick around or they’ll starve. They have to migrate. And it turns out that mated pairs do not necessarily migrate together. We don't know for sure if they actually meet up on their wintering ground. So they may not see each other again until the following spring when nesting activity begins all over again.
Ayesha: What are some of the mating rituals?
Dr. Sargent: Their mating ritual may involve a cartwheel display. Everybody has probably seen the famous cartwheel interaction on television or the internet. This is when the eagles lock talons and seem to fall out of the sky as they spin. Of course that's one of the most spectacular things that you see with the bald eagles. The mating rituals can also involve a roller coaster flight with one chasing the other. They go up to very high altitudes and swoop down and go back up again.
Ayesha: What is the breeding season for bald eagles in Georgia?
Dr. Sargent: The breeding season in Georgia runs from November or early December through early May. Usually we start seeing the first eggs being laid around the December timeframe. Just a few of them lay eggs in December. The majority of them are laying their eggs from January to March and there is a big difference between the timing of the nesting cycle in southern Georgia versus the nesting cycle in northern Georgia. Eagles in the southern part of Georgia have maybe a month to six weeks head start on nesting compared to those in the northern part of the state. We will see young standing in some nests in southern Georgia in late January or early February, whereas in northern Georgia we’re still seeing eggs in some nests at the beginning of March.
Ayesha: So the difference is because of the temperature? Is it?
Dr. Sargent: Sure, and how temperature and rainfall patterns affect the availability of food, especially fish.
Ayesha: What is the difference in the nesting cycle between the southern states versus the northern states in the United States?
Dr. Sargent: Here's another one of those neat things about eagles. While pairs are nesting in Georgia in January, somewhere nearby are eagles waiting to return to their nest sites in Michigan where they will nest in April or the beginning of May. There is at least a 3-3 1/2 month difference in the cycle between eagles nesting in the northern United States versus those in the southern United States.
It's quite an investment if you're a bald eagle pair. To do the work of sprucing up the nest that you've been using for years. To go through the mating ritual, lay the eggs, the incubation and brooding, the fledgling period, and then the eaglets may stick around the neighborhood with their parents for 1 to 3 months. When you add it all up it's a six-month investment for a pair of adult eagles. It’s an extraordinary investment in terms of energy required in rearing young and, of course, there's no guarantee that they'll be successful.
Ayesha: Given that the bald eagle is an apex predator and they do not have a natural predator of their own, what really impacts the successful raising of the hatchlings?
Dr. Sargent: They are at the top of the food chain, but nevertheless there are wildlife hazards for them out there. We have found that great horned owls can sometimes drive eagles off their nests and can certainly take young eagles from nests. Of course it also depends on how diligent the parents are in looking after the nest. Sometimes the eggs and the young can be taken by animals as small as raccoons. Even crows can raid a nest and damage the eggs. And when bald eagle young leave the nest, when they first fledge, like most bird species they are not good at flying. In fact, research shows that 40 to 50% of just fledged eagles crash on their first flight. Sometimes they are injured and in many cases they end up on the ground where they continue to be fed by their parents. When they are on the ground, hiding in shrubbery, they are at the mercy of other predators like bobcats and coyotes. So, even though these are large birds they do sometimes become victims of predation by other species of wildlife.
Ayesha: You've given us an overview of the breeding season, time commitment for a pair of eagles to raise their young, some of the risks the eaglets face during their nest life. Can you tell us a little bit about the incubation and the nest life of the eaglets?
Dr. Sargent: They hatch right around 33 - 35 days and then you're looking at 12 and sometimes 14 weeks before the young fledge the nest. When we visit the nest we can tell how old they are by their size, by the feather development, whether they are standing [or not]. For the first four weeks they are mostly just lying on their bellies. They've got these great big feet the size of the parents’ feet when they are four weeks of age and yet they're not good at standing up. They are very clumsy. They look like a blob with a big bill and big talons. By the age of 9 or 10 weeks you'll start to see them flap their wings. They start jumping up and down in the nest, it's pretty funny to watch. They'll jump and hover for five or six seconds and drop right back into the nest. But sometimes it goes badly for them. They'll start flapping those wings, they'll get airborne and they lift themselves about 3 feet off the nest and a gust of wind blows at the wrong time and blows them right out of the nest. They might cling to a branch somewhere or they may end up tumbling and bouncing from branch to branch. I've seen them do that.
At 12 -13 weeks of age they take their first flight. For the gliding part all they have got to do is hold out their wings - those wings are so large and have so much surface area that they naturally get a lift just like an aircraft’s wings. It's the landing part that gets them. I have seen them leave the nest and go on that first glide. You see them go and you can’t help but wonder if they are thinking, “Oh boy, how am I going to make this happen?” And here comes a tree and they start to lower their feet and they miss-time it, miss the branch they’ve selected, and they actually somersault their way to the ground.
Ayesha: Do bald eagles establish a territory like a lion or a tiger does?
Dr. Sargent: They establish a territory that is centered on the nest and maybe features a radius of one-quarter of a mile around that nest. Sometimes their territory is much smaller, especially if the density- number of pairs of eagles in an area -- is especially high and there is enough food to go around. So if you visit some place like Chesapeake Bay where there's a really high density of bald eagles because there's such a large amount of food and lots of potential nesting sites, then nest territories are smaller. But if the food resources are not especially abundant then the nest territory they defend tends to be larger.
Ayesha: It is my understanding that bald eagles use the same nest over and over again. Is that accurate?
Dr. Sargent: They do. There are some fascinating records of some nests in the country being used for 30-40 years. That's by different generations of eagles, of course, because as I said they don't normally live that long in the wild. One nest that I'm thinking of in the Great Lakes region, I think it was Ohio, was used for over 40 years before the top of the tree failed and the nest fell out of it. There was a nest in the panhandle of Florida that was recorded as weighing nearly 3000 pounds. I believe it was 18 feet tall and about 6 feet wide. That happened because they added new material to the same nest year after year. If you’ve got a great home and you were successful in raising kids last year then why buy a new home? Right? Why go through the trouble of building another one? You show up. There is your mate you haven't seen in five months. Hi, how are you doing? Let's get to work. So they go to their old nest site and it's in pretty good shape. They add more materials to it. Each of them will fly in with branches that they’ve often just broken off from a tree while in flight and not necessarily picked up from the ground. Often times the male will put the materials in the nest and the female will seem to say, “OK, I got it from here, get out of my way,” and she starts fixing things. But they both play a role in sprucing up the nest. Interestingly they will often add a green sprig – a live twig or branch of pine to the nest and we really don't know why. Maybe this is just part of the mating ritual.
Ayesha: That would be interesting to know what exactly that green sprig of branch really means? Could it mean we're getting close to being done sprucing the nest and we're ready to start nesting?
Dr. Sargent: It sure could.
Ayesha: So what exactly do they use besides branches to build their nest? If they're using only branches are they pretty closely knit to ensure that the eggs don't slip out of them?
Dr. Sargent: So the foundation of the nest is large branches with little branches interlocking. It looks like a massive wicker basket. But then in the center they include moss and grasses creating a soft landing space with a little bit of depression and that's where the eggs are found. In the southern parts of the state where Spanish moss is common that's what I'll see in the nest. When the young are about 3 to 4 weeks of age they develop this plumage that we call "thermal down". It looks like gray fuzz and often times it is difficult to see the young because the Spanish moss and the chicks are the same color!
In northern Canada and Alaska where there are no trees eagles nest on cliff faces and sometimes on the ground.
Ayesha: What is the primary diet of a bald eagle?
Dr. Sargent: The vast majority of their food is fish but like all wildlife species there are times when they'll eat something else because other choices become more seasonally abundant. In Georgia probably 70% of their food is fish, but in the winter months they may eat less fish because there are ducks and a bird species called coot that can gather on lakes in large numbers. It is easier to hunt those birds sometimes than it is to catch fish. They eat a number of other things. I have walked around eagle nests and looked at the pieces of critters on the ground. We find a lot of turtle shells. They capture turtles and eat the soft parts. They eat snakes on occasion, and small animals when they can catch them, and other water birds such as ibis. Bald eagles don't hesitate to steal food from other birds. Ben Franklin gave them a bad rap. Franklin famously said that he would rather that the wild turkey was chosen as America’s national symbol. He said that in his opinion the bald eagle had bad moral character because they stole food from ospreys. And they do steal from them!
People assign human emotions to the behavior of a wild animal. It's not like human behavior at all. It has nothing to do with morality. If an eagle can steal food easier than it can capture a meal, then there is no good or bad in it. This is the way they evolved to make a living, so that's what they do.
Ayesha: It’s interesting that you mention that when you walked around under the nest you saw pieces of critters. Given their diet how do the parents keep the nest clean? It must be very messy to have pieces of decomposing critters lying around. How do you keep your nestlings from being totally covered in bacteria?
Dr. Sargent: Late in the nesting season the nest does get pretty smelly, but of course eagles like most birds do not have good senses of smell. You will see all kinds of parts from previous breakfasts and dinners sticking up out of the nest. Fish bones over here, a tail and maybe a leg from a squirrel.
That also is probably part of the motivation for adding new material to the nest the following season. Of course, they have about 6 to 8 months for the nest to air out. And during this time beetles, ants and other creatures eat what wasn't eaten by the young eagles. Mind you they're pretty good about getting every morsel that is brought to their nest. And a lot of the larger parts like bones and hide do end up getting dumped over the side.
Ayesha: Do they make a conscious effort of actually dumping these things off the nest or does it just fall through the crevices?
Dr. Sargent: Some of it actually gets consciously dumped over the side, I think. But a lot of it ends up getting wedged in the branches of the nest itself.
Ayesha: I have very little experience with birds. In fact my only experience is with the robins that have nested in our backyard. What I have noticed with them is that they have this incredible mechanism - so the parents would bring food and as soon as the chicks are fed the chicks have a bowel movement and it is like a little white capsule or pellet that the chicks pass as droppings which then gets carried away by the parents ensuring that the nest stays absolutely clean during their two week nest life. Is that common for bald eagles to?
Dr. Sargent: Did Pete not talk about it in his presentation?
Ayesha: Yes Mr. Griffin did mention that during his presentation that bald eagles have projectile ...
Dr. Sargent: Projectile pooping!!
One of the things that kids get fascinated about is when they hear about projectile pooping - adult birds do it and the young birds, once they are up and walking about the nest, do it. They will pivot so their bottoms are facing outwards from the nest center and they will project their poop. The adults can squirt a stream that can fly up to 30 feet through the air.
Ayesha: From what I remember from Mr. Griffin's presentation was that the droppings are liquid.
Dr. Sargent: Yeah, they are. The white part of bird droppings is actually urine. That’s true even when birds leave behind a small pile of what looks like chalk or solid paste. The green part within the white is the poop.
Ayesha: So why is it liquid and not solid given that their diet includes solid foods?
Dr. Sargent: Bald eagles like other birds of prey regurgitate. They cough up pellets so they don't digest everything.
Birds like owls will swallow their prey whole and later regurgitate a pellet. It looks kind a like an eggroll that has a furry outside instead of a battered outside to it. That pellet contains bones and teeth. It is extremely difficult to digest the really hard parts, and the hard parts could puncture their intestines.
Eagles usually don't swallow their prey whole. When the adults bring food to the nest or capture food for themselves they strip off pieces of meat from an animal carcass. Like owls, they also regurgitate pellets. So you can find pallets around the nest.
Ayesha: I would like to talk a little bit about the cameras that are installed in the eagle nests. Were the nest cams installed primarily to help researchers to understand the behavior of the eagle? Or did they have a dual purpose of being a research tools and creating a relatability factor for the average citizen who might not see a bald eagle on a regular basis?
Dr. Sargent: The cameras have become this wonderful public education tool, haven’t they? In the early days they were used to help us learn more about bird behavior in nests. We wanted to learn more specifics about what they were eating and what they were feeding their young. This is still an important research tool, but nest cams have really developed into a powerful education tool.
Some researchers use nest cams to keep tabs on the nest sites that they cannot visit regularly and so they can download that information. My guess is that the majority of the nest cameras in use now are mostly set up for public education. We are visual creatures and we consume information through all sorts of social media. So naturally we are utilizing this tool for public education.
One of the things that concerns everybody in my profession is that there is a greater and greater disconnect between people and nature. So the nest cam is a great tool in that it brings scenes from nature into people’s homes so they can connect with and understand what's going on out there. But the flipside to that is maybe that experience completely substitutes for actually going out and witnessing nature first hand. I see this a lot when I talk to young people. Kids have access to so much information that I did not have when I was their age. Young people can explain the ins and outs of climate change and holes in the ozone and acidification of the oceans. But they rarely have first-hand experience with wildlife, with understanding the seasons in the life of a wild bird like an eagle, what they're doing at various times of the year, where they are found in the state; things like that. Many people in my generation grew up in the country, often on farms, and so we were immersed in nature every day. So that has changed a lot. I think the [nest] cams have filled that void in that they are providing an educational resource that helps for so many young people who don't spend much time in the outdoors or maybe don't have the opportunity to spend time in the outdoors.
We have two eagle cams in the state right now. The one on Skidaway Island has become an osprey cam because the eagles have not used that nest in the last three seasons. The most well-known one is at Berry College, which is immensely popular and is linked to the Wildlife Resource Division’s website. The pair of eagles there are already fixing up the nest. Here we are in September and they're already doing housekeeping for the next nesting season.
But there are downsides to these nest cams. First of all, logistically it is very difficult to set one up. And secondly, you don't want to do it in a way that actually discourages birds from using the nest or influences the nesting outcome because the camera spooks them.
Another consideration is that sometimes the birds will bring things to the nest that can be disturbing to people who have not been exposed to wildlife behavior. And sometimes young birds die in the nest. Bald eagle young are very aggressive with each other. They don’t all hatch on the same day, because the eggs in the nest – usually two but sometimes three – are not laid on the same day. A female may lay an egg and maybe wait two days before she lays another one. But she starts incubating pretty quickly after that first egg is laid. This is what we called asynchronous hatching. So what happens is the youngest eaglet in the nest is smaller than the older ones. The oldest is stronger and more aggressive about getting food and sometimes the younger one doesn't get enough food and occasionally it starves. It gets weak and the older ones will start picking on it; that's nature. But some people want you to jump in and do something about it. We explain that we let nature take its course. Sometimes nature presents us with some sad scenes.
There are a lot of people who are avid nest cam watchers. I know this because they call and they will say, “So I'm monitoring this nest at a certain location.” Then they say, “I'm really concerned about the second eaglet because it hasn't been fed for quite some time. Can you do something, can you bring food to it?” We should not interfere in these bird’s activities, even when it doesn't work out.
Ayesha: I had heard something similar about an osprey nest on NPR.
Dr. Sargent: Yeah, it was last year that there was a video taken at an osprey nest on Audubon’s Hog Island in Maine.
Eagles raided that osprey nest, attacking the chicks. There were three osprey chicks, almost fully grown, standing in the nest. They were pretty big. And in the distance suddenly materialize two adult eagles flying below the nest. As they climb one of the osprey chicks sees them and goes, “I'm not sticking around for this” and jumps out of the nest. Another one hunches down and lays flat. And the third one is like, “Should I stay or should I go?” and one of the eagles grabs it. I saw comments about it online about what people called “those evil eagles.” No, this is how they make a living. It's not good or bad. This is what they have to do to survive, and it can be shocking sometimes.
Live Nest Cam Links
American Eagle Foundation (Wild nesting pair)
Location: NE Florida
Nesting pair: Romeo and Juliet
Nest Cam: Watch Live
American Eagle Foundation (Wild nesting pair)
Location: Washington DC
Nesting pair: 'Mr. President' & 'The First Lady'
Nest Cam: Watch 2017 Season Reviews. A must see!!
American Eagle Foundation (Non-releasable nesting pairs)
Location: Pigeon Forge, Tennessee
Nest Cam:Watch Live
The following pairs of non- releasable nesting pairs reside within the aviary at the Eagle Mountain Sanctuary.
Eleanor & Roosevelt
Independence & Franklin
Mrs. Jefferson & Isaiah
Georgia Department of Natural Resources
Berry College
Location: Georgia
Nest Cam: Watch Live
American Eagle Foundation (Wild nesting pair)
Location: NE Florida
Nesting pair: Romeo and Juliet
Nest Cam: Watch Live
American Eagle Foundation (Wild nesting pair)
Location: Washington DC
Nesting pair: 'Mr. President' & 'The First Lady'
Nest Cam: Watch 2017 Season Reviews. A must see!!
American Eagle Foundation (Non-releasable nesting pairs)
Location: Pigeon Forge, Tennessee
Nest Cam:Watch Live
The following pairs of non- releasable nesting pairs reside within the aviary at the Eagle Mountain Sanctuary.
Eleanor & Roosevelt
Independence & Franklin
Mrs. Jefferson & Isaiah
Georgia Department of Natural Resources
Berry College
Location: Georgia
Nest Cam: Watch Live
Conservation: Threats that decimated the bald eagle population, timeline of policy implementation, and recovery of species.
Ayesha: Bald eagle is the national bird of the United States. When was it chosen as our national bird?
Dr. Sargent: In 1782.
Ayesha: So almost immediately after independence. Can you give us a sense of timeline of the eagle population - where it was then and when it was listed as endangered and how is the species doing right now?
Dr. Sargent: People have really treated our national symbol pretty badly in American history. It was heavily persecuted and there were no federal or state laws to protect wildlife back then.
By the early 1900s in the U.S., the populations of many wildlife species were greatly reduced. For example, the white-tailed deer and wild turkey were in trouble, and many of the ducks species like the wood duck were in serious trouble. Believe it or not, we used to have elk and bison in parts of the eastern United States, even in the Southeast. Wolves and grizzly bears had much bigger North American ranges 200 years ago. All of those species numbers were greatly reduced by 1900. Around the same time wading birds such as great egrets and snowy egrets were being slaughtered by the thousands because their feathers were used for ladies hat fashions – the millinery trade. The Audubon Society was created by a fellow named George Bird Grinnell who was instrumental in helping to stop that slaughter, along with help from influential sportsmen such as Theodore Roosevelt.
Canada, Mexico, and United States were alarmed by the decline, and in some cases outright disappearance, of many bird species in North America, and so in 1916 these countries signed a treaty called the Migratory Bird Treaty Act. And that act still exists today. It's one of our oldest and most successful pieces of wildlife legislation. It protects nearly every bird species in the United States as well as their active nests, their young and their eggs. Even the mockingbird that nests in someone’s shrub in front of their house is protected by this federal law, but hardly anybody knows that.
But all of this wasn't enough to protect the bald eagle, which was by then heavily persecuted. Some people mistakenly believed that its predation was taking a terrible toll on livestock, especially lambs and calves. The salmon industry had become economically powerful. There was this concerted effort to eliminate eagles where they lived where salmon occurred because eagles, of course, do prey on salmon. For instance, between 1917 and 1952 over 128,000 eagles were killed in Alaska. They called it the eagle war. In some western states ranchers were paying people to shoot eagles, golden and bald, from small airplanes, even into the middle of the last century. In 1940 Congress decided that our national symbol was disappearing and that we had to put a stop to this, and so they created the Bald Eagle Protection Act. In 1962 it was updated to include the Golden eagle, which nowadays is in more serious conservation trouble than the bald eagle.
Then right after World War II along comes DDT. Back then people were dealing with diseases such as malaria that we almost never hear about in the United States anymore. So there were large scale spraying programs that federal and state local governments started. It took us years to realize and prove that DDT was doing more than killing insects. People started noticing dying birds on their lawns soon after neighborhoods were sprayed. The scientist who made this a public story and perhaps wrote the most influential environmental book in the last century was Rachel Carson, and the book was Silent Spring.
Although bald eagles were still abundant in parts of the country, scientists and citizens who studied them in the 1950s noticed that few of their nests were successfully fledging young. The birds were still laying eggs, but the young didn’t survive. Lab experiments helped to prove cause-and-effect, that DDT caused birds to lay thin-shelled eggs. It was interfering with their ability to take calcium from their bones and produce a normal egg. So the eggs were cracking in the nests. It was not just bald eagles; it was also decimating peregrine falcons, ospreys, and even brown pelicans. So Carson’s book brought public attention to the problem and President Kennedy created a commission to study her results. It took 10 years and a lawsuit by the Environmental Defense Fund (EDF), and in 1972 the newly-formed Environmental Protection Agency banned the use of DDT in the U.S.
Data from eagle nests in Georgia help to tell the story. (Mr. Sargent pointed to the bar graph that he had open on his computer screen to show me the statistics). That bar graph there on the far left is the 1970s. That’s the number of occupied eagle nests in the state of Georgia, which is none! In the entire decade of the 1970s there were no successful nests recorded in Georgia. On the far right is 2017 and now it's over 200. In 2000 we counted 55, and did not exceed 100 for the first time until 2007. It has been over 200 for three consecutive seasons. Last winter they were 218 active nests in the state, about 70% of which were successful. Look at the dramatic turn-around, how eagle numbers measured by successful nests have changed in 40 years, and in large part that's due to the banning of the DDT use in this country.
That's not the only reason, of course. The Endangered Species Act was established by Congress in 1973, which set very specific criteria for assessing when a species warrants protection, and spells out actions that must be implemented. The word ”endangered” legally means a species is in jeopardy of becoming extinct. “Threatened” means that a species is in jeopardy of becoming endangered. The Endangered Species Act established fines and other penalties for harming listed species, even prison terms. It says that you have got to figure out what habitats are critical for their survival and determine whether or not there is sufficient habitat. If there isn’t enough then you've got to buy some, improve some, or find some other way to protect it, maybe through partnerships with private landowners. It says that we have to study the species and figure out the causes for its decline. And once we've got those answers then we have to write and implement what's called a “Recovery Plan,” which is written by the experts for that species and is designed to restore that species to a population goal. That's what happened with the bald eagle. In the early 1970s it was listed as endangered federally and in states such as Georgia. By the mid-1980s there was a recovery plan that had been drafted just for the southeastern US. The bird was in such dire trouble in the Southeast that in Georgia our goal for saying that this has been a successful effort was a really low bar of success. We were shooting for just 20 active nests in the whole state. Now 35 years later we have 10 times that many nests in the state.
Ayesha: That is amazing.
Ayesha: How does Georgia compare to the rest of the United States for nesting sites?
Dr. Sargent: We have far more nests than the southwestern states and the small northeastern states, but far fewer than Florida, the Great Lakes states, the Chesapeake Bay Region, and the Northwest. For example, there are over 1,300 nests in Florida.
Ayesha: In conservation of course everything has to be a multi pronged approach. We have to address it from policy, education, research and fines/penalties. You have touched upon policy and research. Can you talk about what else was taken into account to safe guard the species? And is the bird still listed as endangered?
Dr. Sargent: The bald eagle is no longer listed as endangered by the federal government. It's a great success story.
Public education was a big part of it, much of which was based on lessons learned from the immense amount of research that went into the recovery plans.
The other thing that played a major role in the recovery of the bald eagle was the protection and recovery of the habitats, especially old trees. The southeastern United States saw extensive clear cutting from the late 1880s to the 1920s. So most of the old growth trees in Georgia had been cut. This was something that happened all across the United States. It started in the northeast then went to the Great Lakes, then to the northwest and the southeastern United States. When we see a bald eagle nest in the wild its mostly in old trees, 90-95% are in pine trees in Georgia. They are usually older specimens in a forest. They often don't have the typical conical pointed crown; they often have flattened crowns. This is typical of old trees, especially those that grow in somewhat open forests not crowded by surrounding pine trees. Eagles like to have a canopy over their nests. They don't usually nest at the very top of the tree where the eggs and young would be exposed to the sun and to the elements. Usually the nests are 6 to 10 feet down from the top of the tree. So that open canopy is important because a bird with a 7 foot wingspan doesn't want to have to maneuver through a really dense crown to get to its nest. And it doesn’t want its young to be crashing through the branches when it's time for them to leave the nest. And those older flat top trees have really large limbs, which make great girders for holding up a nest that can weigh hundreds of pounds if not more. So it took time for us to recover the loss of those old growth forests in Georgia because so much of it was lost by the 1920s. So that was part of the picture. Identifying their critical habitats and making sure these was sufficient habitat protected for their nesting success, for their feeding success and for their wintering habitat needs.
When you stop and think about it, the bald eagle is not the only species that benefits from all these conservation steps, nor would it be the only species harmed if its habitats were damaged. They live in aquatic environments and they're at the top of the food chain. So if the bald eagle is in trouble and its numbers begin to decline again then we need to sit up and take notice, not just because it's our national symbol, but also because there might be something toxic about the environment. This is a water-based environment in which they live, and so this is vital to our survival, too. It is also vital to our economic survival because the areas in which they live and fish are also areas in which we harvest fish, crabs and so many other kinds of seafood. So helping the recovery of the bald eagle also led to the improvement of the quality of these wetland habitats where they lived and hunted.
Another part of the recovery effort involved hacking, which was done successfully with recovery efforts for peregrine falcons in the 1970s and 1980s. In Georgia during 1979 to 1995 biologists received eaglets from nests in northern United States where eagles were much more abundant. These 8-9-week-old young were reared in what looked like cages on stilts. These were hacking towers and this was done in three locations including Sapelo Island. Biologists would feed these eaglets in these cages without the eaglets seeing that they were being fed by people. So, they did not imprint on people and learn that they could depend on human beings for food. When they got to be about 12 weeks old, the cage doors were opened, allowing the eagles to decide when it was time for them to take flight and learn to make a living on their own. That was part of the recovery effort.
Ayesha: What kinds of fines were in place? Mr. Griffin had mentioned that if someone finds a bald eagle feather they needs to turn it in to the US Fish and Wildlife Services. We can’t keep a bald eagle feather because it is federal crime and has a penalty of $10,000 per feather. Can you please elaborate on the fines and prison term?
Dr. Sargent: The fines for killing a bald eagle when the species was listed as endangered could be in the neighborhood of $100,000.
Ayesha: Fine for owning a bald eagle feather is $10,000?
Dr. Sargent: When it was listed under the Endangered Species Act. The fines are still substantial, but likely not as high as they used to be.
In fact, according to the law you are not supposed to have a feather collection from native species of any kind unless you have a federal permit from the U.S. Fish and Wildlife Service.
Ayesha: If the bald eagle is not listed as endangered then what is its status – threatened? Vulnerable?
Dr. Sargent: The federal Endangered Species Act has its own ranking and each state usually has a law that mirrors that act. In Georgia it is called Endangered Wildlife Act. Under Georgia law the bald eagle is listed as a threatened species, but it is no longer listed by the federal government as endangered or threatened.
Of course, the species is still federally protected under the Bald and Golden Eagle Protection Act. That law protects them and, like the Endangered Species Act, establishes fines for the persecution of bald eagles. That is the primary federal law that protects bald eagles and golden eagles in this country now.
Ayesha: So irrespective of how it is listed given that we have the Bald and Golden Eagle Protection Act it still gives it the protection it needs.
Dr. Sargent: Yeah, that is right.
When the federal government delisted the bald eagle that means it took it completely off the list. It went from endangered to threatened in 1999 and went from threatened to delisted in 2007. Even though it was delisted, the federal government established bald eagle habitat management guidelines to provide continued protection of nests from harm and disturbance. What that means is that if somebody wants to construct a development near a bald eagle nest tree, it has to meet certain criteria. So I get calls from the public and I coordinate with Fish and Wildlife Service about proposed developments and even certain kinds of land management activities like intensive forestry activities. Some of them may be permissible provided that they occur outside a specified buffer zone from the nest tree itself. There are primary and secondary buffer zones. A primary buffer zone is a 330 foot radius around the eagle nest tree. Within that primary buffer zone there are a lot of restrictions. You are not supposed to go in there and put up a house right next to eagle nest tree. You are not supposed to clear-cut the forest within that buffer zone. There are number of other activities that are regulated. Some of them are allowable but only outside of the nesting season. We work with the U.S. Fish and Wildlife Service as partners to educate the public by explaining these guidelines and the permit requirements.
Ayesha: Does your office pretty much know every single nesting site in the state?
Dr. Sargent: No, I would never say that. We survey the state and I get a lot of great calls from people who discover nests that I did not know about. Georgia covers 58,000 square miles and so it is not realistic to think we have found every single nest in the state.
Ayesha: There is so much development in Atlanta and we have lost quite a bit of our canopy as a consequence of clear cutting. How do we know that a nest is not lost in this clear cutting? Is there a process builders have to follow to ensure we don’t accidentally loose some eagle nests?
Dr. Sargent: There is a national law called the National Environmental Policy Act, which requires environmental assessments of federal actions that involve major undertakings on federal land. There is something similar in our state call GEPA. So disturbances on state lands, whether it is a new development, large scale logging operation, construction, or highway construction -- those things have to be reviewed by the state agencies. One of those agencies is us (Georgia Department of Natural Resources-DNR). Large-scale land projects in the City have to be evaluated, too. They have to be presented to the public for public review and have to be sent to state agencies like Georgia DNR for the review process
For instance, one of our partners is the Georgia Department of Transportation. They do road modifications and road maintenance regularly. They routinely send us a statement of work, the plan to work on a certain road, in a particular county, and during a certain time frame. They ask us to assess if there are any wildlife concerns in the area. One question on their checklist is, are there any bald eagles nests nearby? So we are constantly receiving plans like that and I get to weigh in on those.
Ayesha: These are state agencies involved in construction work and needing to cut some trees but what about private builders? What if a developer acquires 30 acres of land and now wants to build a neighborhood and decides to clear-cut all 30 acres of the existing trees?
Dr. Sargent: It happens and we have some instances in which we are alerted about the presence of a bald eagle nest. So in these cases we call the owner and encourage them to get in touch with the U.S. Fish and Wildlife Service. We explain to them that the eagle nest trees and the birds themselves are protected under federal law.
Is it possible a nest tree can be cut down in the process of development? It is possible. But there are a lot of people who are very attentive and who are big fans and admirers of bald eagles, and so the conservation of the species and the protection of its nests continues to be a team effort.
Ayesha: Recently there has been a lot of speculation/concern about the direction the EPA is taking. Personally I'm concerned about environmental protection laws changing and/or being repealed by the EPA. If that happens then overtime those changes in the laws are eventually going to impact wildlife conservation. Are you concerned about that?
Dr. Sargent: Our country has come a along way in terms of the evolution of laws that protect wildlife such as the bald eagle. There's a great deal of support from the public in Georgia on behalf of the conservation of nongame wildlife species. No, I cannot say I'm pessimistic that we are going to eliminate some of these laws. There's always discussion with every new federal administration with regards to the future of Endangered Species Act, for instance. Naturally, anybody working in the wildlife profession pays attention to that, is concerned about that, recognizes that some of these laws have to be tweaked through time for the sake of improvement and because we are always learning new things about conservation strategies. But I'm optimistic that laws like that have so much public support that they won't be, as you say, eliminated.
As I said, we worry more about people becoming increasingly disconnected from nature. There was a popular book that was written several years ago that talked about nature deficit disorder. The importance of getting young people in the outdoors because if they don't know about it, they won’t appreciate it, and if they don't appreciate it, then future generations are not going to be inclined to take care of it.
So if you look at the DNR’s website we run a lot of youth camps. These camps to a large degree are geared to exposing kids to nature because they are the conservationists of the future. We have got to get them to care about wildlife.
Dr. Sargent: In 1782.
Ayesha: So almost immediately after independence. Can you give us a sense of timeline of the eagle population - where it was then and when it was listed as endangered and how is the species doing right now?
Dr. Sargent: People have really treated our national symbol pretty badly in American history. It was heavily persecuted and there were no federal or state laws to protect wildlife back then.
By the early 1900s in the U.S., the populations of many wildlife species were greatly reduced. For example, the white-tailed deer and wild turkey were in trouble, and many of the ducks species like the wood duck were in serious trouble. Believe it or not, we used to have elk and bison in parts of the eastern United States, even in the Southeast. Wolves and grizzly bears had much bigger North American ranges 200 years ago. All of those species numbers were greatly reduced by 1900. Around the same time wading birds such as great egrets and snowy egrets were being slaughtered by the thousands because their feathers were used for ladies hat fashions – the millinery trade. The Audubon Society was created by a fellow named George Bird Grinnell who was instrumental in helping to stop that slaughter, along with help from influential sportsmen such as Theodore Roosevelt.
Canada, Mexico, and United States were alarmed by the decline, and in some cases outright disappearance, of many bird species in North America, and so in 1916 these countries signed a treaty called the Migratory Bird Treaty Act. And that act still exists today. It's one of our oldest and most successful pieces of wildlife legislation. It protects nearly every bird species in the United States as well as their active nests, their young and their eggs. Even the mockingbird that nests in someone’s shrub in front of their house is protected by this federal law, but hardly anybody knows that.
But all of this wasn't enough to protect the bald eagle, which was by then heavily persecuted. Some people mistakenly believed that its predation was taking a terrible toll on livestock, especially lambs and calves. The salmon industry had become economically powerful. There was this concerted effort to eliminate eagles where they lived where salmon occurred because eagles, of course, do prey on salmon. For instance, between 1917 and 1952 over 128,000 eagles were killed in Alaska. They called it the eagle war. In some western states ranchers were paying people to shoot eagles, golden and bald, from small airplanes, even into the middle of the last century. In 1940 Congress decided that our national symbol was disappearing and that we had to put a stop to this, and so they created the Bald Eagle Protection Act. In 1962 it was updated to include the Golden eagle, which nowadays is in more serious conservation trouble than the bald eagle.
Then right after World War II along comes DDT. Back then people were dealing with diseases such as malaria that we almost never hear about in the United States anymore. So there were large scale spraying programs that federal and state local governments started. It took us years to realize and prove that DDT was doing more than killing insects. People started noticing dying birds on their lawns soon after neighborhoods were sprayed. The scientist who made this a public story and perhaps wrote the most influential environmental book in the last century was Rachel Carson, and the book was Silent Spring.
Although bald eagles were still abundant in parts of the country, scientists and citizens who studied them in the 1950s noticed that few of their nests were successfully fledging young. The birds were still laying eggs, but the young didn’t survive. Lab experiments helped to prove cause-and-effect, that DDT caused birds to lay thin-shelled eggs. It was interfering with their ability to take calcium from their bones and produce a normal egg. So the eggs were cracking in the nests. It was not just bald eagles; it was also decimating peregrine falcons, ospreys, and even brown pelicans. So Carson’s book brought public attention to the problem and President Kennedy created a commission to study her results. It took 10 years and a lawsuit by the Environmental Defense Fund (EDF), and in 1972 the newly-formed Environmental Protection Agency banned the use of DDT in the U.S.
Data from eagle nests in Georgia help to tell the story. (Mr. Sargent pointed to the bar graph that he had open on his computer screen to show me the statistics). That bar graph there on the far left is the 1970s. That’s the number of occupied eagle nests in the state of Georgia, which is none! In the entire decade of the 1970s there were no successful nests recorded in Georgia. On the far right is 2017 and now it's over 200. In 2000 we counted 55, and did not exceed 100 for the first time until 2007. It has been over 200 for three consecutive seasons. Last winter they were 218 active nests in the state, about 70% of which were successful. Look at the dramatic turn-around, how eagle numbers measured by successful nests have changed in 40 years, and in large part that's due to the banning of the DDT use in this country.
That's not the only reason, of course. The Endangered Species Act was established by Congress in 1973, which set very specific criteria for assessing when a species warrants protection, and spells out actions that must be implemented. The word ”endangered” legally means a species is in jeopardy of becoming extinct. “Threatened” means that a species is in jeopardy of becoming endangered. The Endangered Species Act established fines and other penalties for harming listed species, even prison terms. It says that you have got to figure out what habitats are critical for their survival and determine whether or not there is sufficient habitat. If there isn’t enough then you've got to buy some, improve some, or find some other way to protect it, maybe through partnerships with private landowners. It says that we have to study the species and figure out the causes for its decline. And once we've got those answers then we have to write and implement what's called a “Recovery Plan,” which is written by the experts for that species and is designed to restore that species to a population goal. That's what happened with the bald eagle. In the early 1970s it was listed as endangered federally and in states such as Georgia. By the mid-1980s there was a recovery plan that had been drafted just for the southeastern US. The bird was in such dire trouble in the Southeast that in Georgia our goal for saying that this has been a successful effort was a really low bar of success. We were shooting for just 20 active nests in the whole state. Now 35 years later we have 10 times that many nests in the state.
Ayesha: That is amazing.
Ayesha: How does Georgia compare to the rest of the United States for nesting sites?
Dr. Sargent: We have far more nests than the southwestern states and the small northeastern states, but far fewer than Florida, the Great Lakes states, the Chesapeake Bay Region, and the Northwest. For example, there are over 1,300 nests in Florida.
Ayesha: In conservation of course everything has to be a multi pronged approach. We have to address it from policy, education, research and fines/penalties. You have touched upon policy and research. Can you talk about what else was taken into account to safe guard the species? And is the bird still listed as endangered?
Dr. Sargent: The bald eagle is no longer listed as endangered by the federal government. It's a great success story.
Public education was a big part of it, much of which was based on lessons learned from the immense amount of research that went into the recovery plans.
The other thing that played a major role in the recovery of the bald eagle was the protection and recovery of the habitats, especially old trees. The southeastern United States saw extensive clear cutting from the late 1880s to the 1920s. So most of the old growth trees in Georgia had been cut. This was something that happened all across the United States. It started in the northeast then went to the Great Lakes, then to the northwest and the southeastern United States. When we see a bald eagle nest in the wild its mostly in old trees, 90-95% are in pine trees in Georgia. They are usually older specimens in a forest. They often don't have the typical conical pointed crown; they often have flattened crowns. This is typical of old trees, especially those that grow in somewhat open forests not crowded by surrounding pine trees. Eagles like to have a canopy over their nests. They don't usually nest at the very top of the tree where the eggs and young would be exposed to the sun and to the elements. Usually the nests are 6 to 10 feet down from the top of the tree. So that open canopy is important because a bird with a 7 foot wingspan doesn't want to have to maneuver through a really dense crown to get to its nest. And it doesn’t want its young to be crashing through the branches when it's time for them to leave the nest. And those older flat top trees have really large limbs, which make great girders for holding up a nest that can weigh hundreds of pounds if not more. So it took time for us to recover the loss of those old growth forests in Georgia because so much of it was lost by the 1920s. So that was part of the picture. Identifying their critical habitats and making sure these was sufficient habitat protected for their nesting success, for their feeding success and for their wintering habitat needs.
When you stop and think about it, the bald eagle is not the only species that benefits from all these conservation steps, nor would it be the only species harmed if its habitats were damaged. They live in aquatic environments and they're at the top of the food chain. So if the bald eagle is in trouble and its numbers begin to decline again then we need to sit up and take notice, not just because it's our national symbol, but also because there might be something toxic about the environment. This is a water-based environment in which they live, and so this is vital to our survival, too. It is also vital to our economic survival because the areas in which they live and fish are also areas in which we harvest fish, crabs and so many other kinds of seafood. So helping the recovery of the bald eagle also led to the improvement of the quality of these wetland habitats where they lived and hunted.
Another part of the recovery effort involved hacking, which was done successfully with recovery efforts for peregrine falcons in the 1970s and 1980s. In Georgia during 1979 to 1995 biologists received eaglets from nests in northern United States where eagles were much more abundant. These 8-9-week-old young were reared in what looked like cages on stilts. These were hacking towers and this was done in three locations including Sapelo Island. Biologists would feed these eaglets in these cages without the eaglets seeing that they were being fed by people. So, they did not imprint on people and learn that they could depend on human beings for food. When they got to be about 12 weeks old, the cage doors were opened, allowing the eagles to decide when it was time for them to take flight and learn to make a living on their own. That was part of the recovery effort.
Ayesha: What kinds of fines were in place? Mr. Griffin had mentioned that if someone finds a bald eagle feather they needs to turn it in to the US Fish and Wildlife Services. We can’t keep a bald eagle feather because it is federal crime and has a penalty of $10,000 per feather. Can you please elaborate on the fines and prison term?
Dr. Sargent: The fines for killing a bald eagle when the species was listed as endangered could be in the neighborhood of $100,000.
Ayesha: Fine for owning a bald eagle feather is $10,000?
Dr. Sargent: When it was listed under the Endangered Species Act. The fines are still substantial, but likely not as high as they used to be.
In fact, according to the law you are not supposed to have a feather collection from native species of any kind unless you have a federal permit from the U.S. Fish and Wildlife Service.
Ayesha: If the bald eagle is not listed as endangered then what is its status – threatened? Vulnerable?
Dr. Sargent: The federal Endangered Species Act has its own ranking and each state usually has a law that mirrors that act. In Georgia it is called Endangered Wildlife Act. Under Georgia law the bald eagle is listed as a threatened species, but it is no longer listed by the federal government as endangered or threatened.
Of course, the species is still federally protected under the Bald and Golden Eagle Protection Act. That law protects them and, like the Endangered Species Act, establishes fines for the persecution of bald eagles. That is the primary federal law that protects bald eagles and golden eagles in this country now.
Ayesha: So irrespective of how it is listed given that we have the Bald and Golden Eagle Protection Act it still gives it the protection it needs.
Dr. Sargent: Yeah, that is right.
When the federal government delisted the bald eagle that means it took it completely off the list. It went from endangered to threatened in 1999 and went from threatened to delisted in 2007. Even though it was delisted, the federal government established bald eagle habitat management guidelines to provide continued protection of nests from harm and disturbance. What that means is that if somebody wants to construct a development near a bald eagle nest tree, it has to meet certain criteria. So I get calls from the public and I coordinate with Fish and Wildlife Service about proposed developments and even certain kinds of land management activities like intensive forestry activities. Some of them may be permissible provided that they occur outside a specified buffer zone from the nest tree itself. There are primary and secondary buffer zones. A primary buffer zone is a 330 foot radius around the eagle nest tree. Within that primary buffer zone there are a lot of restrictions. You are not supposed to go in there and put up a house right next to eagle nest tree. You are not supposed to clear-cut the forest within that buffer zone. There are number of other activities that are regulated. Some of them are allowable but only outside of the nesting season. We work with the U.S. Fish and Wildlife Service as partners to educate the public by explaining these guidelines and the permit requirements.
Ayesha: Does your office pretty much know every single nesting site in the state?
Dr. Sargent: No, I would never say that. We survey the state and I get a lot of great calls from people who discover nests that I did not know about. Georgia covers 58,000 square miles and so it is not realistic to think we have found every single nest in the state.
Ayesha: There is so much development in Atlanta and we have lost quite a bit of our canopy as a consequence of clear cutting. How do we know that a nest is not lost in this clear cutting? Is there a process builders have to follow to ensure we don’t accidentally loose some eagle nests?
Dr. Sargent: There is a national law called the National Environmental Policy Act, which requires environmental assessments of federal actions that involve major undertakings on federal land. There is something similar in our state call GEPA. So disturbances on state lands, whether it is a new development, large scale logging operation, construction, or highway construction -- those things have to be reviewed by the state agencies. One of those agencies is us (Georgia Department of Natural Resources-DNR). Large-scale land projects in the City have to be evaluated, too. They have to be presented to the public for public review and have to be sent to state agencies like Georgia DNR for the review process
For instance, one of our partners is the Georgia Department of Transportation. They do road modifications and road maintenance regularly. They routinely send us a statement of work, the plan to work on a certain road, in a particular county, and during a certain time frame. They ask us to assess if there are any wildlife concerns in the area. One question on their checklist is, are there any bald eagles nests nearby? So we are constantly receiving plans like that and I get to weigh in on those.
Ayesha: These are state agencies involved in construction work and needing to cut some trees but what about private builders? What if a developer acquires 30 acres of land and now wants to build a neighborhood and decides to clear-cut all 30 acres of the existing trees?
Dr. Sargent: It happens and we have some instances in which we are alerted about the presence of a bald eagle nest. So in these cases we call the owner and encourage them to get in touch with the U.S. Fish and Wildlife Service. We explain to them that the eagle nest trees and the birds themselves are protected under federal law.
Is it possible a nest tree can be cut down in the process of development? It is possible. But there are a lot of people who are very attentive and who are big fans and admirers of bald eagles, and so the conservation of the species and the protection of its nests continues to be a team effort.
Ayesha: Recently there has been a lot of speculation/concern about the direction the EPA is taking. Personally I'm concerned about environmental protection laws changing and/or being repealed by the EPA. If that happens then overtime those changes in the laws are eventually going to impact wildlife conservation. Are you concerned about that?
Dr. Sargent: Our country has come a along way in terms of the evolution of laws that protect wildlife such as the bald eagle. There's a great deal of support from the public in Georgia on behalf of the conservation of nongame wildlife species. No, I cannot say I'm pessimistic that we are going to eliminate some of these laws. There's always discussion with every new federal administration with regards to the future of Endangered Species Act, for instance. Naturally, anybody working in the wildlife profession pays attention to that, is concerned about that, recognizes that some of these laws have to be tweaked through time for the sake of improvement and because we are always learning new things about conservation strategies. But I'm optimistic that laws like that have so much public support that they won't be, as you say, eliminated.
As I said, we worry more about people becoming increasingly disconnected from nature. There was a popular book that was written several years ago that talked about nature deficit disorder. The importance of getting young people in the outdoors because if they don't know about it, they won’t appreciate it, and if they don't appreciate it, then future generations are not going to be inclined to take care of it.
So if you look at the DNR’s website we run a lot of youth camps. These camps to a large degree are geared to exposing kids to nature because they are the conservationists of the future. We have got to get them to care about wildlife.
Ongoing concerns and recovery plan
Ayesha: Before we end is there anything I missed and you would like to add?
Dr. Sargent: I did not talk about this but you look at how far bald eagles have come in the state in terms of the number of nests now compared to 1970s. It is very encouraging. I mean hugely encouraging.
But there are things that we need to stay on top of, things that continue to concern us. We have problems with eagles being hit by cars. Eagles, like vultures, eat road-side carrion and are slow to get off the ground because they are heavy bodied birds. They don't leap into the air like songbirds, but instead tend to hop in order to get forward momentum and get some lift under their big wings. They may choose to get airborne by deciding to fly right in the middle of the road because it's open. They don’t dart off through the trees. I remind people to slow down when they see big birds on the side of the road.
There is a disease, actually a neurological disorder caused by a toxin, which was discovered in Arkansas in 1994 and then was discovered in Georgia in 1998. It's called avian vacuolar myelinopathy (AVM). It turns out that this toxin is found in certain kinds of photosynthetic bacteria, what we call cyanobacteria. This toxin bearing cyanobacteria sometimes grows on exotic aquatic plants, especially a plant from South America called Hydrilla. It occurs in many waterways in Georgia such as J. Strom Thurmond Reservoir north of Augusta. Since 1998 we have collected over 90 dead eagles from the reservoir. As far as we know at least 40 of them died of AVM. So what happens is the hydrilla and its cyanobacteria are eaten by aquatic birds such as the coots I previously mentioned. They occur in large numbers in winter on some reservoirs like J. Strom Thurmond. The neurotoxin breaks down the nerves in the brains of the coots. Their nervous systems misfire so they can't fly or swim properly. If you are a bald eagle perched in a tree deciding if you're going to eat fish today or one of these coots, the choice is easy. The sick coot is swimming abnormally, something is wrong with it, it's going to be easy to catch. So they eat the coot and end up with the neurotoxin in their body and it in turn destroys their nervous system and they don't survive.
Ayesha: So research is ongoing? It's not like we figured out DDT, the species is delisted and now our job is done. The teams of researchers are constantly working to make sure that there are no new threats to the species.
Dr. Sargent: Yes
Ayesha: This plant Hydrilla is from South America and not native to the United States, right? So is part of the research and effort dedicated to eliminating this plant or is this not a big concern?
Dr. Sargent: The Army Corps of Engineers published a management plan for the reservoir last year with input from the public and from agencies like Georgia DNR. That plan calls for selective use of herbicides, herbicides that are safe to be used in aquatic environment, along with the stocking of Asian grass carp in the reservoir. The carp are sterile and so they can be released in the environment without fear that they will over-populate. They eat submerged aquatic plants, so this management strategy is a two-pronged approach. And we are monitoring the eagles to see how they respond to this. Hopefully, the hydrilla abundance declines and perhaps disappears, which would mean that coots, and in turn eagles, would no longer be harmed by AVM on the reservoir.
Ayesha: Let me ask you one final question? Do you have a message for the readers especially our young readers?
Dr. Sargent: Yes, don't just read about wildlife in social media. Get together with a mentor, somebody who is an “outdoor person” and go see wildlife and learn about it. It's a whole lot cooler and memorable to see wildlife in person then to read about it.
We have got bird watching camps in Georgia. I lead a weeklong camp that’s all about ornithology on the Georgia coast in June every year. We have young people, teenagers from all over the state and other states, show up. Some of them have never gone bird watching in their lives. They get to learn all about all the animals, not just birds, up-close and in person. They get to see them and to understand the environment in which they live, what they are dependent upon for survival, and what people in agencies like mine are doing to help these species. More importantly, they learn what they can do to either become professional in a wildlife-related career or just try to help out as private citizens.
Ayesha: Thank you, for that wonderful message!! Thank you also for your time. I really enjoyed learning about the bald eagles. This was very informative and engaging and I hope it is for the readers too!
Dr. Sargent: You are welcome. You can tell I enjoy talking about eagles!
Dr. Sargent: I did not talk about this but you look at how far bald eagles have come in the state in terms of the number of nests now compared to 1970s. It is very encouraging. I mean hugely encouraging.
But there are things that we need to stay on top of, things that continue to concern us. We have problems with eagles being hit by cars. Eagles, like vultures, eat road-side carrion and are slow to get off the ground because they are heavy bodied birds. They don't leap into the air like songbirds, but instead tend to hop in order to get forward momentum and get some lift under their big wings. They may choose to get airborne by deciding to fly right in the middle of the road because it's open. They don’t dart off through the trees. I remind people to slow down when they see big birds on the side of the road.
There is a disease, actually a neurological disorder caused by a toxin, which was discovered in Arkansas in 1994 and then was discovered in Georgia in 1998. It's called avian vacuolar myelinopathy (AVM). It turns out that this toxin is found in certain kinds of photosynthetic bacteria, what we call cyanobacteria. This toxin bearing cyanobacteria sometimes grows on exotic aquatic plants, especially a plant from South America called Hydrilla. It occurs in many waterways in Georgia such as J. Strom Thurmond Reservoir north of Augusta. Since 1998 we have collected over 90 dead eagles from the reservoir. As far as we know at least 40 of them died of AVM. So what happens is the hydrilla and its cyanobacteria are eaten by aquatic birds such as the coots I previously mentioned. They occur in large numbers in winter on some reservoirs like J. Strom Thurmond. The neurotoxin breaks down the nerves in the brains of the coots. Their nervous systems misfire so they can't fly or swim properly. If you are a bald eagle perched in a tree deciding if you're going to eat fish today or one of these coots, the choice is easy. The sick coot is swimming abnormally, something is wrong with it, it's going to be easy to catch. So they eat the coot and end up with the neurotoxin in their body and it in turn destroys their nervous system and they don't survive.
Ayesha: So research is ongoing? It's not like we figured out DDT, the species is delisted and now our job is done. The teams of researchers are constantly working to make sure that there are no new threats to the species.
Dr. Sargent: Yes
Ayesha: This plant Hydrilla is from South America and not native to the United States, right? So is part of the research and effort dedicated to eliminating this plant or is this not a big concern?
Dr. Sargent: The Army Corps of Engineers published a management plan for the reservoir last year with input from the public and from agencies like Georgia DNR. That plan calls for selective use of herbicides, herbicides that are safe to be used in aquatic environment, along with the stocking of Asian grass carp in the reservoir. The carp are sterile and so they can be released in the environment without fear that they will over-populate. They eat submerged aquatic plants, so this management strategy is a two-pronged approach. And we are monitoring the eagles to see how they respond to this. Hopefully, the hydrilla abundance declines and perhaps disappears, which would mean that coots, and in turn eagles, would no longer be harmed by AVM on the reservoir.
Ayesha: Let me ask you one final question? Do you have a message for the readers especially our young readers?
Dr. Sargent: Yes, don't just read about wildlife in social media. Get together with a mentor, somebody who is an “outdoor person” and go see wildlife and learn about it. It's a whole lot cooler and memorable to see wildlife in person then to read about it.
We have got bird watching camps in Georgia. I lead a weeklong camp that’s all about ornithology on the Georgia coast in June every year. We have young people, teenagers from all over the state and other states, show up. Some of them have never gone bird watching in their lives. They get to learn all about all the animals, not just birds, up-close and in person. They get to see them and to understand the environment in which they live, what they are dependent upon for survival, and what people in agencies like mine are doing to help these species. More importantly, they learn what they can do to either become professional in a wildlife-related career or just try to help out as private citizens.
Ayesha: Thank you, for that wonderful message!! Thank you also for your time. I really enjoyed learning about the bald eagles. This was very informative and engaging and I hope it is for the readers too!
Dr. Sargent: You are welcome. You can tell I enjoy talking about eagles!
Who To Support:
Please find listed below organizations dedicated to preserving bald eagles and other birds of prey. Please take a few minutes to visit their website to pledge your support by signing petitions, making a donation and staying informed. Should you wish to make a contribution please send your contributions directly to an organization of your choice. You can also call the individual organization to enquire about their bird of prey presentations and other educational outreach programs they offer.
American Eagle Foundation
Charlie Elliott Wildlife Center
Audubon society
The Center for conservation biology
The Peregrin fund
Birds of Prey Foundation
Please find listed below organizations dedicated to preserving bald eagles and other birds of prey. Please take a few minutes to visit their website to pledge your support by signing petitions, making a donation and staying informed. Should you wish to make a contribution please send your contributions directly to an organization of your choice. You can also call the individual organization to enquire about their bird of prey presentations and other educational outreach programs they offer.
American Eagle Foundation
Charlie Elliott Wildlife Center
Audubon society
The Center for conservation biology
The Peregrin fund
Birds of Prey Foundation