Flight from Extinction: Restoring Whooping Cranes to North America
In 1942, the whooping crane population in North America drastically declined to a mere 16 birds. Intense efforts by the Patuxent Wildlife Research to breed cranes in captivity and reintroduce them into wild habitats began in the 1960s. This work has helped the population grow to about 500. U.S. Geological Survey Research Manager Dr. John French discusses whooping crane reintroductions, the research that enabled such work and its implications for other reintroduction projects.
|John French: Good afternoon everybody. I'm glad you could get here on a winter day. A little snowy outside but I'll tell you a little bit about today about whooping cranes in North America. Maybe some of you know a little bit about these birds already. They're absolutely spectacular bids and one of the most endangered species of birds in the world and surely in North America. Actually I think if I've got this right the California condor has a fewer individuals in their population than does the whooping crane. It's not a trade we like to see. We'd like to get beyond that but it's a very, very highly endangered bird.
So today we'll tell you a little bit about their biology. A little bit about the organization of our efforts to restore these birds to North America and a little bit about how some of the research that we do at Patuxent helps us organize and come up with methods for restoring these birds.
|01:06||That's a whooping crane, extremely tall, very striking looking birds. They're about, they're up to five feet, they stand up to five feet tall so they're a substantially large bird and they have a very striking set of plume with bright white with black wing tips and you can see in the portrait on the right there that red top of the head. Ah, that's bare skin that is used very frequently in signaling between animals. It puffs up during aggressive encounters in the case if the bird is upset. It also gets a lot redder during the breeding season indicating they're all fired up for breeding. And everything's kind of neat about the birds is their bright yellow eye there. And you can see up front I've got a wing from, actually it's a yearling or not quite yearling whooping crane.
||You can see the white plumage on the wing and the black wing tips there and a little bit of brown. The juvenile plumage is a kind of a mottled warm brown and mixed with white. This bird was one of the birds' wing came from the bird that was one of the birds we were trying to restore and was, no I can't remember that one that was killed by one of its siblings or by a predator but in any case we recovered the carcass. Oftentimes we will recover those carcasses and they go to the Smithsonian and it so happens that some of the folks from Patuxent work at the Smithsonian and curate the North American collection of birds. So I was in there talking to these guys and they were showing me all their whooping cranes specimens so I borrowed their wing for this talk.
For those of you that are bird watchers cranes are in the ordered group of gruiformes and in the gruidae there are only 15 species of cranes in the world and almost all of them are threatened or even endangered worldwide.
||There are a couple of species that do pretty well but most of them are quite rare. Let me tell you a little bit about ecology of these birds. As you know most birds migrate but populations of different groups within the whooping crane population in North American and by the way whooping cranes are only ever found in North America so all the birds that are alive today are in North America.
Whooping cranes have both a migratory habit and a sedentary habit and there are very few species of birds that have both of those life history habits within the population. They're territorial birds like most are during the breeding season but they are also territorial during the winter when they defend territories to provide or to secure food resources for themselves. They keep other animals away. They eat just about everything. They're omnivorous. They'll eat fish and crawfish and crabs and tubers and vegetation and just about anything, insects.
||And they have a very distinctive courtship behavior. Maybe you've seen pictures of them dancing where the male and the female are standing close to another and jumping up in the airs flapping their wings and flailing their legs up and it's a very dramatic courtship dance and they also have a very loud call, the so called whoop, which is where they get their name. Actually this call is kind of interesting because when you hear it, it sounds like a single call but indeed in fact it is two birds calling together. The so called unison call and the timing of that call, the male and the female calling together is thought to be very important in courtship and bringing these birds into reproductive condition. Whooping cranes have a very widespread distribution in North America or did have when they were a little more numerous.
||They're essentially birds of the grasslands, of wet grasslands. They range from the Canadian, Northern Canadian taiga down to the gulf coast of New Mexico and I mentioned that there was a sedentary population, let's if I can do this here. Right here in Louisiana where these yellow dots are, we know that in historical times, there was a small population of cranes that spent a whole year there. They both bred there and spent the winter there.
There are a couple of other interesting things about this figure. Look at this large red area here in the high planes of Mexico. This is an area of wintering habitat for whooping cranes, was an area of wintering habitat for whooping cranes back maybe a hundred or two hundred years ago when there were, when there were more whooping cranes in North America, and by the way there were never a very numerous species but certainly more numerous than they are now. The interesting part about that particular area of Mexico is that it's very arid.
||We've been, I was down there a few years ago looking at some of the wintering areas that are used by sandhill cranes. Sandhill cranes are the other crane species in North America. A little smaller bird, a brown bird. They are now very numerous in North America and they winter down in this area of the high central plains of Mexico. There are however, these perched wetlands periodically throughout that territory there which is pretty good wintering habitat apparently.
Whooping cranes were reduced primarily by hunting, believe it or not and by the loss of good wetland nesting habitat. A very important moment in the history of the conservation of whooping cranes came in 1952 when Robert Porter Allen produced his monograph, which was sponsored by the National Audubon Society. At that time, he gathered together all the information that we had in, you know, scholarly journals and in museums and in field notes and all sorts of diaries and such of explorers in North America.
||He gathered together all that nice information and from that he produced this map that you see on the screen and the monograph itself really galvanized the conservation community to look a little more carefully at this beautiful bird and do more to preserve it. The Aransas Wood Buffalo flock is the one wild flock that remains in North America. And here's Wood Buffalo National Park up in ah, straddles the border between northwest territories and Alberta, that's where the wild population of whooping cranes spends the winter. They migrate all the way down here to the gulf coast of Texas and most of that population winters at the Aransas National Wildlife Refuge, official wildlife refuge on the coast and most people who have seen whooping cranes see them down there at Aransas. That's a long migratory road and something like 2300-2400 miles so a long way to go.|
||So I'm going to tell you a little bit about the Aransas Wood Buffalo Flock. We knew quite a bit about whooping cranes from that monograph put together by Robert Porter Allen publishing what did I say, '58? No I forget. Something like that but a the time it was published we didn't know where the breeding grounds of these birds were. They took off. We saw them during migra-- we saw them in the winter time, saw them during migration and then they disappeared into Canada. We didn't know where the heck they went.
At some point in 1959, there was someone from the Canadian Forest Service who was serving for forest fires, saw these great big white birds nesting essentially in the wetlands as you see here in that photograph. The wetlands look like this in Northern Canada. It was kind of interesting because that's not really the kind of habitat that we thought these birds liked.
||So obviously we kind of revised our idea of what was important habitat for these birds when we discovered that. This is a picture taken from a plane that when surveys are done each year during the breeding season to count the nest and to count the eggs and the chicks that are hatched from those eggs. It's very difficult territory to get around and you really have to go by air and you can see it's just vast, vast territory of wetlands, little pockets of water and you can see a great big patch of ice still on the little lake there.
So it's, with rather rugged weather up there, they seemed to do fine. This population is growing quite, quite fast. There are not too many of them. There are only about, now they're a little bit more than 200, more like 250 but the population is growing quite fast, a rather exponential growth in population. We hope that the territories that we've set aside in Canada and in Texas at the Aransas National Wildlife Refuge are adequate to hold that growing population. We're a little concerned about that.
||If you look at this picture, it looks like there's tons of territory up in Canada, indeed there probably is, ah plenty of adequate habitat there but in Texas I'm not so sure. In 1966, during one of these surveys, the biologist noticed that one of the birds was a fledgling or old enough to fledge that is fly, learn to fly but this bird had kind of a droopy wing and had difficulty flying. So they landed the plane, actually they went back to get a helicopter came out and got-- landed the helicopter in this area and were able to capture this bird. Indeed it did have a broken wing, could not fly. That bird was the first bird brought in, first whooping crane brought into captivity and was sent to Patuxent where I work here in Laurel, Maryland the next year and that bird became the founder of all the captive populations of whooping cranes in North America.
||That bird was named the CanUs, Canada-US who marked the great cooperation that was underway then and still is underway to conserve this bird. CanUs was a male as I say, he had a kind of gimpy wing and we repaired that wing and then it kind of broke again we had to amputate the wing. We learned a lot about breeding birds in captivity from CanUs. One thing we learned was that you need to have two wings to properly copulate with female birds because what they do is they get up on the back of the female and balance using their wings.
We couldn't quite figure out why none of the eggs or very, very few of the eggs were fertile when we paired CanUs with these other birds. Then we realized he, you know, he just wasn't able to copulate properly. From that we developed an artificial insemination program for cranes and there's an awful lot of sort technical biological background to that including finding a medium to transfer the sperm from the male, collected from the male to the female and timing and all that kind of stuff.
||That artificial insemination technique has been used many, many times. We still use it today for perfectly interfertile pairs that we have at Patuxent but it really increases the fertility of the eggs that are produced and it's a huge bone for us when we're trying to produce a lot of birds in captivity.
As I mentioned the rest of this population maybe or certainly are increasing and one of the things that's of concern, a couple of things of major concern and it is, it's all centered around the US side of the habitat. Down in Texas, there's a lot of human building going on, right? And now coming up very close to the edge of the refuge. The birds don't really know where the boundary of the refuge is. They like to get off the refuge and go wherever they want to go and they've used the uplands outside of the Aransas wetland area for forging and just loafing and hanging out.
||Now a lot of that territory has been taken by human building. Another great concern is the availability of fresh water to the Aransas coastal margins. It's an estuary and the Guadalupe River that comes down from San Antonio, I think it's in another large town I'm sorry I've forgotten but with the growing population in the metropolitan San Antonio, a lot of water is being taken out of the river, you know, people need water to drink.
So what's happening is the flows in the river are decreasing, which means the solidity is increasing. The plume of salt water is moving up river. Well these birds they're OK in salt water except that in the winter time, they really depend on a feeding on blue crabs to keep their, you know, physiological condition up and in particular females feed on those crabs and increase their calcium intake in preparation for breeding the next year and we see that without high proportioned crabs in their diet, the egg production the following is not very good.
||So we're quite concerned about that. In fact there's all sorts of, if you're interested in this you can Google on and find all sorts of interesting conservation techniques. I'll tell you about one that's kind of cool. The, you know, if you get to just go any old river and stick a pipe in there and it turn on a spigot and take out water. Most states have a fermenting process and they regulate or they measure the amount of flow in the river and they, you know, hand out permits for extraction of water. So a bunch of conservation groups got together and said, well we want a permit for, you know, extra amount of gallons per minute of whatever it is and they asked for quite a lot.
||And the Texas water board said what are we going to use it for? And they said, nothing. We're going to live in the river for the, you know, keep the habitat in the estuary downstream at the right level of salt, of salinity. And Texas being rather conservative state and focused pretty much entirely on development just couldn't handle it. And they just said, no and the folks said, what are you talking about? We've applied and what?
The end result was they dismantled the water board and the whole thing went to court and nobody could get any water out of the river for a year or so. Interesting, technique didn't really work quite the way we'd hoped but uhm... So these are the kind of practical conservation measures that certainly are required for preserving whooping crane populations and I think it shows very clearly some of the conflicts between human use obviously and wildlife use.
||And it's not a matter for biologists to determine, it's public issue of course but those are the kind of things that people did. Got a little off the topic there. So let me tell you about whooping cranes. They're about 500 a little bit more of them, a little more than 500 extent that is alive today in North America that's all the whooping cranes there are and I've kind of listed where these whooping cranes reside. Most of them were in the Aransas Wood Buffalo population.
There are about 25 left in population of restored cranes, restored whoopers in Florida in Central Florida that we started with about 15 years ago. This restoration program didn't really work very well. I think we got up to about 80 or 90 birds in that population and there was always very high mortality among those birds that were released, mortality from bobcats.
||Part of the mortality was due to the fact that Florida's in the midst of a, you know, 20-year drought essentially and the roosting habitats and nesting habitats but particularly roosting habitats for these birds were disappearing. Good roosting habitat is water about 6 to 14 inches deep and what whoopers and many waiting birds is get in the deepest water they can, lift up one leg, stick their beak under their wing and go to sleep. Why they do it in the water? Because the bobcat can't sneak up on them in the water. It makes too much noise they, get alerted and they fly away.
Well these birds were roosting on dry land because of the lack of wet habitat and they were getting picked off pretty quickly. We have about a hundred birds now in the eastern migratory flock and I'm going to tell you quite a bit more about this flock and there are a hundred and something like 150 birds in captivity, most of them at Patuxent, Patuxent Wildlife Research Center here in Laurel but there are a number of other captive populations around North America as well. Principally at the International Crane Foundation, ICF in Baraboo, Wisconsin, a non-profit or non-governmental organization, a very strong partner in crane conservation overall.
||Calgary Zoo has a bunch of birds. San Antonio has a couple of birds but the principal breeding populations are Patuxent and the International Crane Foundation. In all of those groups, there are something like 32, maybe now up to 35 pairs that breed in captivity and from those pairs, all the birds that we released back into the wild. All of the ones that we use to restore a lot of populations, they all come from these 32 pairs. So it's very important for us to maintain these populations in good shape and breed them properly and all that kind of stuff and I'll tell you a little more about that later.
||Now turning to the eastern migratory flock, this is our, the recovery team's principal restoration effort at the moment. The strategy for introducing or reintroducing an eastern migratory flock was this. We wanted to establish, we needed to establish a new migratory route. There were no whooping cranes in the east. Remember from that map, there were little dots all throughout the east. There was some wintering going on up the east coast. And in fact even up in the Chesapeake Bay into this area. There were apparently wintering whooping cranes from we know that from museum records and such.
So we knew there were whooping cranes in the east. What we didn't know quite, we don't know quite where. So we wanted to establish this migratory route from the Necedah National Wildlife Refuge in Wisconsin down to Northwest Florida. But how do you do that? Because you know cranes there to teach these birds how to migrate, how the heck do you do? Do you establish a new migratory route.
||We couldn't just let them go. I think they just wouldn't do it. Through the really imaginative thinking of a number of different people came up with this idea of imprinting whooping crane chicks on an ultralight aircraft and flying them south behind the aircraft in the spring of their first year when they are susceptible to imprinting on a migratory route, to teach them how to migrate.
Now you've probably seen the movie Fly Away Home, you guys seen that movie? What is it? There are geese that are flying behind that... Well get your mom to get that movie for you will you? It's a really interesting movie where they, they find a bunch of goslings and teach them how to migrate behind an ultralight aircraft. So that movie actually provided some of the impetus for this idea and in fact the folks that did the movie are now our partners in this whole restoration effort and they fly the planes and take the birds south.
||So it was a very interesting idea, not everybody thought it was going to work but it does work. It's kind of neat. So OK, we produced the chicks and train them at Patuxent, that is we breed the birds in captivity, produce the chicks, imprint them on the ultralight aircraft there and then we ship them up to this refuge in Central Wisconsin where they learn to fly where they fledge behind an ultralight aircraft. And then in the fall they take off and fly south on their migratory route and then we release them into these nice habitats in Florida. And that's all it takes.
OK. In order to do this, it's a complicated project and all sorts of partners including all the folks you see here. The ones listed Operation Migration International Crane Foundation or NGOs, the others are federal or state agencies. So we've all come together to bring what expertise each of us have to this partnership in order to get this migratory flock going.
||So at Patuxent we produce these chicks and there are couple of interesting things to note here. Here is some of the technicians gathering some semen from the male crane for some artificial insemination efforts. Here are great big whooping crane eggs in an incubator. We incubate them, for most of their life as an embryo in the egg, we'd stick those eggs under captive sandhill cranes that we have at the center and the reason we do that is because it turns out that despite all our research on the micro environment of a nest, that is what temperature and humidity and turning rate these eggs experience under a whooping crane and we do this with telemetered eggs where we get all sorts of little measurement devices in there and they send signals back to our computer and we know almost exactly what's going on in the nest and we can reproduce it in incubator.
||But there's something about crane motherhood that we're not measuring or whatever so we know the eggs hatch an awful lot better if we stick them under sandhill cranes too for most of their incubation periods. So we do that and then we bring them into these incubator for the last week or so of their incubation and we hatched them in a lab and then, you know, when these cute little guys hatches. And then we have to teach them how to eat and to walk and to drink and all that kind of stuff and to do that we're all in costume like these guys right here. And there's one of the costumes over there which I hope everybody's going to try on after the talk.
You know I mentioned we have only 32 pairs in like all the captive flocks. So we, the usual collective size for these birds is two. They lay two eggs and they stop. Well that's not enough for us so what we do is when an egg is laid in one of our captive pairs, we go in there we remove the egg and we put a wooden egg back in the nest and this keeps the female in condition and we keep removing that second egg so we can get three, four, five sometimes up to eight eggs from a single female.
||So we got many more than, we usually produce 40 or so, 45 eggs from 10 or 12 breeding pairs we've got in captivity at Patuxent. In any one year, we've got about, well we've got about 18 or 20 pairs that will breed but in any one year only 10 or 12 do produce eggs.
Those later eggs get a little bit smaller and the egg shells get a little thinner. The females are looking a little more ragged lay off and drop all their feathers despite the fact we give them a whole bunch of fish and a whole bunch of calcium and a whole bunch of whatever, it's still awful. It's a big egg and you can imagine, very high energy yolk. The female puts a lot into those eggs So we can't get more than really six or seven good eggs from a female.
||Then we get all these eggs and they hatched and then we got all these chicks running around and they're hatched in the lab and now what do you do with them? It's just a huge, huge effort to teach these chicks to raise them essentially. So we have people running around in costumes, holding a puppet hen like this, which obviously looks quite a bit like a whooping crane and we point out their food bowl to them and we stick the beak of the puppet head in the water, we stick it in the food bowl and a little bit of food attaches to the end of the bill and the chicks instinctively go peck at the end of the bill.
In fact we put this red tape around the end of the bill because red is a very, you know, vibrant color and attracts these chicks. The adult whoopers don't have red but we found that the puppet works better if we put a little red tape at the end of the bill. So you can see that sort of happening here in the slide and of course those of you that are parents remember that young organisms need to eat a lot and often and they don't, they're a little grumpy when they don't eat and all that kind of stuff.
||So every half hour we got to go feed these 30 or 40 chicks and they don't really know how to feed themselves so we've got 10 or 12 people that are running around in costume in the heat of the summer teaching these chicks how to eat and it's really a lot of work. And we really just give a great sigh of relief when these chicks learn to eat on their own and which happens after about 10 or 12 days but it's a great moment when one of these chicks start to eat off on their own. I think you can remember that as parents too, yeah.
So let's see, the other thing we do for these birds is give them a lot of exercise. These are so called precocial species. The avian chicks are divided roughly into two groups based on their life history as chicks, precocial and altricial.
||Precocial birds get up and walk within a day or two of being hatched. Altricial chicks are those that are usually naked, blind, and sitting in the nest like a passerine, a songbird and they just sort of begging for food with their eyes closed from their parents, taking food from their parents. So very different kind of strategies about how chicks develop within the bird world, pretty much divided into precocial and altricial that is birds that get up and run around and birds that just sit here and want to be fed.
These birds get up and run around which means their legs grow very, very quickly but it's very important for them to get exercises early or this very rapid growth of their legs doesn't proceed properly, we often find that we've got conformational problems that legs start to rotate, the toes clasp together in a way that they don't walk very well and it's very, very difficult for us to give these chicks enough exercise.
||If they're in the wild, they get up and they leave the nest and their parents are wandering around the marsh. Their parents have legs about this long and they take a huge step and these tiny little chicks have to take about 15 steps to keep up with each one step of their parents. Parents are running around picking up food and giving it to them, they're getting a lot of exercise. In fact one of those birds, one of those pairs of birds in Florida in our non-migratory flock nested and raised some chicks right next to like a hundred yards to somebody's house.
The people were very interested in this whole situation. They had a movie camera on the nest, you know, almost the whole time. And looking at that movie, I learned more about crane chick biology than I had in years prior to that. The thing that struck me the most was how much exercise these little chicks get. They're climbing over things. They're falling in the water. They're swimming. They're trying to keep up with their parents. They're getting lost. They're getting stuck. They're running around.
||There's just nothing we can do to reproduce in the lab but we tried. In fact we have a little swimming pool for them right here. We try and give them as much swimming time as possible. We try and introduce them to kind of wetland habitats and that kind of thing.
Well at about five or six weeks of age, their wings start to grow, they're getting ready to fledge. Their breast muscles, their pectoral muscles are getting larger. They're starting to flap their wings, they're getting ready to fly. At that point, we box them up in these very large crates here and we ship them up to Wisconsin where they learn to fly behind the ultralight aircraft and we have already imprinted them on this aircraft as little chicks. In fact, you may not know this but when parental birds are sitting on the nest, they call to the embryos even while the chicks are still in the egg especially and the chicks started to call back within a day or two of hatching.
||So they establish a little bit of a bond even before they hatch. Well knowing this what we've done for these birds that are being hatched in the incubators, we play in the incubator sounds of a marsh, sounds that they would likely hear if they are in the wild, frogs and herrings and kingfishers and other birds that they are likely to hear and we also play the sound of the ultralight aircraft engine. So that when we start to train them behind the ultralight, they're not all freaked out of that and we know this makes a huge difference.
So the ultralight kind of just becomes part of their world and by the way here's the little cab or a little trike of the ultralight, it's not a very, you know a hefty thing here and these guys get up five-six a hundred feet up in the air and I don't know I'm glad somebody, other partners are doing that part of the project.
||When they've learned to fly up in Wisconsin in the fall some time usually early October migration begins and here is a picture of a bunch of birds from I think it's 2006 flying behind the ultralight aircraft. That's a great day for us. It's the culmination of an awful lot of work by an awful lot of people to get these birds to fly and besides it's an absolutely beautiful sight as well.
So as I mentioned we fly them south. We go from the Necedah National Wildlife Refuge down here to Chasawiska National Wildlife Refuge in Florida. Now you asked whether the training actually works and why would we do that? Well in fact it does work and here's a little bit of data to show you that. What we're looking at here is the flight paths of birds that were hatched in the spring of 2002 and they were migrated south behind the aircraft in the fall of 2002.
||So here is the flight path of the birds coming north again on their own without an aircraft in 2003 and you can see they flew pretty, and each of these lines represents about six or seven birds. They flew almost directly to Necedah. Necedah's one red bird kind of got off that a little bit, very instructive to go back and check the history of this bird. This was a bird that did not fly had a little bit of an injury so it didn't fly with the flock on the way down and in fact the bird was cratered up and put in the truck and carried along each day with the group, there's a big ground crew that comes along with ultralight aircraft and when the ultralight lands with the birds they set up a big pen. The birds spend the night at the pen and then they take off again the next day.
||So this bird that was injured was put in the truck with the ground crew in a box and put back into the pen with his mates every night so it maintains some, you know social skills with birds still thought it was a bird which is an important thing. And then the bird improved and at about Southeastern Tennessee it was strong enough to fly with the group and you can see and it flew the rest of the way down to Florida.
So you can see on the way back in the spring, it flew very nicely north to the point where it no longer had experienced the migratory route and then got all discombobulated and headed off here into Ohio and finally we went to capture this bird brought it back to Necedah, spent the summer in Necedah, found a mate and now it's one of those birds that's actually breeding up there and migrates very well. So that's kind of a nice story but instructive about how the training that goes in that fall period when they're available, when they're open to this kind of training really does work.
||And then again the picture on the other side here is their 2003 fall migration south again and they did just fine going south. So migration training does work but it's not perfect and here I've plotted a whole bunch of locations of birds for several years of the project and you can see that some of them get way off course over here, some of these were able to pick up and move back to Wisconsin and become part of the central area. Some of them we were not able to. Some of them in Michigan still fly to Michigan.
And I will tell you that within the group, within the partnership, we had a lot of discussion about what's the right thing to do for these birds? We know that birds, that all animals may disperse out of their, away from their natal territory and is what we were seeing here natural dispersal? Or is this just kind of, these birds just didn't quite get it?
||You know they didn't, we didn't train them properly and we blew it in some way. A lot of discussion about this and I think certainly in their early days when we only had a few birds every bird was so important we just couldn't let it out of our grasp and had to do it just right and we go pick it up all the time. Now that we have a few more birds I think we're changing our point of view on this a little bit not only because we can't do it in every case but because it's probably not the right thing to do.
We're sort of changing from an individual model of wildlife management to a more population level model and I think we'll continue to change that perspective as we go along. I will tell you though that some of the people in New York that we're able to see these whooping cranes, they did not last to come get those birds, they wanted them there to look at.
||Yeah? That's a really good question. We wish we knew a little bit more about that. What we do know is that, no they, most of the breeders got right back to the breeding area, however, these birds don't really start to breed until they're three sometimes four maybe as old as five years of age and we don't, during those flights over the breeding grounds in Aransas we don't account for those birds. We were only able to find birds on their territories and we kind of have an idea where the territories are.
So every once in a while see, some yearlings or juvenile birds hanging around or birds that aren't on territories but they're not banded and we don't know where they go. And we do have scattered records throughout Saskatchewan and Alberta and even over further west. So there are birds out there. We just don't know how often this happens or whether this is extremely regular, you know that kind of stuff.
||One of the, this is a little more technical side of the whole issue of restoring rare critters to the wild, one of the things that's very difficult for us is that the breeding of birds in captivity is quite variable pair by pair. We have some pairs in captivity that breed very well and it produced a lot of chicks and we've released a lot of their chicks into the wild. We have some pairs in captivity that don't breed very well at all so we've only released a few of their maybe even one or maybe none of their offspring into this population.
So what does that mean for the population that gets put back into the wild, it means they're very highly related and the chances of pairs forming among those released birds that are related and hence a high level of inbreeding and a risk from deleterious allele showing up because of inbreeding is quite high, that's not a a good thing.
||On the other hand, we're putting birds into the wild that we know do pretty well, they breed. You know, of course they're breeding in captivity they're not breeding in the wild but at least they're breeding, right? So we got very concerned, so that's sort of the trade off where we don't want to put birds in the wild that aren't vigorous but we don't want to have them all very closely related either. We got quite concerned about the genetic relatedness of the birds that we were sticking back into the wild a couple of years ago and we decided to stop breeding those birds in captivity that it produced so many chicks. A huge discussion about this and there were arguments back and forth but at that point it seems like the right thing to do.
And then we realized that really one of the greatest risk, you know, we realized we knew this all along but we started to add up the fact that one of the greatest risk of a small restored population in the wild is just for chance catastrophic events wiping out the entire population and you have a chance catastrophic event that kills 500 herring gulls, no big deal.
||There are probably 20 million herring gulls in North America but if you've got only 37 birds and you'll lose 30 of them, that's huge. So we really need to get a lot of birds out there. We just need a big population as fast as possible. So we did a little bit of calculation about how these different things impact the population of birds and I just point you to these graphs. We're looking at annual survival here along the Y axis and we can see as inbreeding goes up, it appears that annual survival does seem to go down. So there maybe indeed an inbreeding, a deleterious effect of inbreeding on these birds. But looking on the other side of it, are those birds that come from very productive pairs of whooping cranes in captivity, are those birds better at surviving because we know they do very well in captivity.
||So we looked at that and we saw yeah, it looks like there's better survival among those chicks that come from pairs of birds in captivity that produce a lot of chicks. So the vigorous breeders in captivity seemed to produce higher quality chicks as well. These data are a little contradictory and in fact what you see here for those of you that are statistically inclined is that each point has a very, very wide range of variability about it so we can't really say anything definitive. There are a little bit of trends here.
So what we're doing with this set of information is sort of modelling the trade offs between these two constraints of population. At some point we get a little more data, we'll be able to parameterize these models and say a little bit more about this. We've done a lot of research at the Patuxent Wildlife Research Center over the last 40 years on whooping cranes. A lot of which has helped, almost all of it was directed toward helping us produce populations for chicks for restoration in the wild and there were a whole number of things.
||And I'm just going to point out one of them to you and we've done a lot of migration work on migration training. What does it take to imprint these birds on the aircraft? What does it take to do a successful migration. We started with some geese. We worked with sandhills first and by the way that's a very standard method of working with endangered species. What we do is we look for a very closely related bird species. Do all our experimentation on that species make our mistakes on that species and then take those techniques and work with the rare endangered species And for that reason we've got many more sandhill cranes in captivity at Patuxent than we do have whooping cranes.
Now some of the ideas that have come up about migration training is, I haven't described you this entirely but flying birds behind an ultralight is not an easy thing to do. These ultralights are a little touchy. They don't like bad weather. It takes a long time for us to get these birds down south.
||So we're thinking well maybe there's another way to migrate these birds that's a little surefire, a little less difficult. Well someone came up with the idea of a blimp. You'd suspend them in a great big cage behind the blimp and you just go slowly and you know, you don't have to worry about rain or wind or whatever. So we started a few experiments where we'd put some sandhill cranes in a great big cage and hold it up a flagpole and look to see how they reacted to this, they didn't like it too much but then we took that cage and we put it in the back of a pick up truck. We drove around because we weren't quite sure what they would do.
Say you're going through the air at 20 miles an hour in the cage. Are they flapping? Are they going to want to fly? Are they going to want to just sit tight? We didn't know. So we drove around in the truck. These were very preliminary type of experiments. So far we haven't perfected that technique but it's still actually a good idea to kind of try some of these things.
||Another more wacky idea was someone said, well you know what we really ought to do is just fly the route ourselves with an IMAX camera take a picture of the route just like a crane chick would see it in its first migration take those crane chicks, stick them in an IMAX theater and play them the movie and maybe they'd learn it. And I dares ay they would. To tell you the truth I think it might work.
I mean there are all sorts of things to be worked out and, you know, somebody's ideas they're amusing and they're fun to think about you know, kind of an armchair ecology kind of way but that's sort of, was the state of things for the ultralight migration before we got going, right? So one of the really fascinating and exciting parts in doing conservation science or any kind of science is coming up with these ideas and then going through all the effort to test them to check them out, provide some data to justify or throw out this technique and that kind of thing.
||So it's really, it's a wonderful program to work in and a lot of it is because of some these exciting ideas. We've had very good success in restoring this eastern migratory flock. There are about a hundred birds now that are migrating, They're not breeding very well. We've got some challenges but the flock is really doing pretty well. Their mortality is low. They're migrating beautifully. They're forming pairs and they're nesting and they're laying eggs. The funny thing is they seemed to be abandoning their clutches at times before the chicks hatched.
And we've got all sorts of ideas about why that might be and we're starting to collect data to find and sort that out but it's a little disconcerting. And overall for whooping cranes in North America and I recall they're only just a few more than 500 of them. We're happy to see the continuous growth of the Aransas Wood Buffalo population and we think we've got a pretty good start on some of these, we're introducing other new populations.
||The Whooping Crane Eastern Partnership has worked very, very well. It was, the partnership itself was kind of necessary. There was an awful lot of work to be done but it's challenging to keep that partnership working together all in the same direction. There are many, many different points of view in that group. One of the things in that partnership that's worked extremely well is the outreach team. There's an outreach in education team that has been very, very effective at helping provide information about these birds and really building support for this whole program.
And I'd like acknowledge Joan Guilfoyle who was one of the early members of the Whooping Crane Eastern Partnership. She was on the outreach and education team. I think your expertise is in outreach. Whoever came up with that idea, and probably it was you Joan. It's really been one of the most successful parts of this whole operation and it's great.
||In fact the whole project itself got the Department of Interior Secretary's 4c's Award in 2003 for our good work. There are many challenges left to restoring cranes in North America. Some of them we're addressing. Some of them we don't really know how to address. So there's plenty of work to do and I hope some of you get challenged to help either with whooping cranes or other, restoring other species in North America. So thanks much and I'd be happy to take any questions.