It’s the Season! Counting Eggs and Hoping for Chicks

It takes a lot of eggs to make a whooping crane! If that sounds a bit bizarre, please bear with me; I can explain it.

It’s official that out in the fields and wetlands of Wisconsin – around Necedah National Wildlife Refuge – that nesting season is underway. One way or another, happy or sad, there will be news to share.

But for this post, I’m focusing on the eggs – and eventually the chicks – that will be produced by the captive populations of whooping cranes. There are five centers with captive breeding populations that are the source of all but seven of the cranes that have been released by the Whooping Crane Eastern Partnership (WCEP) into Wisconsin, since 2001, and Louisiana, since 2011. (The seven birds that did not hatch from eggs of the captive population, are cranes that have hatched in the wild in Wisconsin – exciting! But not nearly enough for the flock to survive on its own.)

By far, the majority of captive eggs for WCEP come from the population of whoopers at either the International Crane Foundation (ICF) here in Wisconsin, or Patuxent Wildlife Research Center in Maryland. The remaining sources of captive breeding whooping cranes are the Calgary Zoo in Alberta, Canada, the San Antonio Zoo in Texas, and the Audubon Center for Research on Endangered Species, in New Orleans.

Eggs Don’t Equal Chicks

One thing you can be sure of if you follow the production of eggs – ICF very helpfully posts an Egg Score Card with their news – the number of new little whooping crane chicks for 2015 will not equal the number of eggs produced. Not even close.

Last year, according to a report at Operation Migration, there were 106 eggs produced from captive breeding that were potentially available for the WCEP programs. Doesn’t that sound like it might be a bumper crop?

Whooping Crane eggs in incubators (Photo courtesy Patuxent National Wildlife Research Center)

Well . . . not exactly. From that number only 25 chicks were available for WCEP to divide among the ultralight training program (7 chicks), the parent release program which was new in 2013 (4 chicks), and for the non-migratory flock that is being established in Louisiana (14 chicks). So here’s what happened to all those other eggs: a good many of them were infertile; some were broken by the cranes in their nests, and sometimes chicks that hatch do not survive.

Breeding Whooping Cranes at the International Crane Foundation

From the data provided by WCEP and its partners, I was getting the picture that probably more than half the eggs produced would never become whooping cranes. I needed help understanding this seemingly poor outcome, and Bryant Tarr, Curator of Birds at ICF, was happy to oblige.

“The numbers game with captive produced whooping cranes is always a bit of a guess,” he told me in an email last year. He added that breeding through artificial insemination – necessary “because we wish to control the genetics to avoid inbreeding in this tiny population” – makes the process even more of a guess. (He recently, reconfirmed for me that the info he shared a year ago is “all pretty much the same for this year.”)

Bryant said: “Natural fertility is usually higher. Fertility by artificial insemination usually results in about 50-60% fertile eggs in whooping cranes. And yes, some of the birds break their eggs. This likely happens more in captivity than in the wild and there may be many factors involved.” He suggested though, that wild nests are faced with the threat of predators, which of course are no threat to captive birds, “so there is kind of a wash going on there.”

A whooper chick that hatched from an egg of the captive population is then raised by disguised and costumed humans, using aides like this puppet-head of an adult whooping crane. (An International Crane Foundation photo)

Bryant added that about 40 fertile eggs were expected from the entire captive flock, but “40 fertile eggs does not equal 40 chicks for release!” he assured me. “You have to figure in ‘hatchability’ the percent of fertile eggs that hatch ( usually close to 80%) and survival after hatch (some young ones just don’t make it) and that is usually about 80% too.”

Count the Eggs and Do the Math

Applying Bryant’s percentages to last year’s count of 106 eggs reveals that the 25 whooping crane chicks that resulted were right on the mark. After accounting for 49 infertile eggs, and 19 broken ones, there were 38 potential eggs from the captive populations in 2014. Figuring that only about 80 percent of them actually hatched, and that only 80 percent of those hatchlings would survive for release, it’s true that approximately two dozen little whooping crane chicks is exactly what you would expect.

Stay tuned for news of this year’s egg totals and the whooper chicks that hatch for 2015. Egg and chicks season is underway, and at ICF the Egg Scorecard is currently reporting that eight eggs, so far, have been laid by the whooper population in residence there. It is too soon to know if 4 of them are fertile. But here are the relevant details on the other four: 2 have been identified as infertile; none are broken; and one has hatched!

I bet it won’t be long before there’s another Egg Score Card report with fresher news – so look for that! And I hope you’ll check back here as well; soon The Badger and the Whooping Crane will report on the eggs, nesting and hatching occurring among the Wisconsin whooping cranes out in the wilderness areas of our state.

Where the Birds Are: Various Whooping Crane Populations Explained

When we speak or write about whooping cranes it’s always good to know which population of the  whoopers we’re referring to. Although there are only a small number of these big, wonderful North American birds alive today (approximately 400 in the wild, and near 200 in captivity), they are spread across a variety of habitats and locations.

Some are divided among 3 captive populations, and others are in groups designated by the U.S. Fish & Wildlife Service as “non-essential experimental populations.” And 250, or more, are in the one and only self-sustaining wild flock.

So you can see, when discussing whooping crane news, it’s helpful to know which of these groups of cranes is the one from whence the news is coming. Here at The Badger and the Whooping Crane, we’re most interested, naturally, in what’s happening with the whooping cranes that migrate from Wisconsin to Florida. Known affectionately at this blog as “our cranes”, or the “Wisconsin cranes,” their official designation is the tongue twister “non-essential, experimental Eastern Migratory Population (or, to simplify,  the EMP). Responsibility for the EMP cranes falls to the Whooping Crane Eastern Partnership, written about here earlier.

An adult whooping crane pair that live within the captive population at the International Crane Foundation in Baraboo, WI. (Photo by Joel Trick, used courtesy of WCEP

But the EMP cranes – “our cranes” – are just one part of the bigger picture for the whooping crane story, and a post clarifying the various populations seems overdue. So what follows is a description of each one – population by population.

The Wild Ones

Each whooping crane in existence today is derived from the one self-sustaining wild flock – which has been brought back, literally, from the brink. The birds in this population migrate between Canada’s Wood-Buffalo National Park in northern Alberta, and the Texas Gulf Coast, crossing the international border twice each year.

Aransas National Wildlife Refuge was established in 1937 to protect critical habitat for the endangered whooping crane. (Photo courtesy USFWS: Aransas NWR page: multimedia galleries)

This flock reached its historic low point during the winter of 1940-41 when only 15 birds were counted. Public education campaigns and conservation efforts intensified after that, and the numbers have crept back up – at a snail’s pace, but consistently upwards.

A long history of close cooperation between the wildlife agencies in both countries gets a lot of the credit for keeping the species alive.

A photo of Wood Buffalo National Park in northern Canada wheret he only self-sustaining natural flock of whooping cranes nests each summer. (Photo courtesy citizenshift.org)

My source for the historical data on this Aransas-Wood Buffalo flock, and for the next section on Captive Breeding is a “Status Survey and Conservation Action Plan” (Curt Meine and George Archibald, 1996).  It’s online at the Northern Prairie Wildlife Research Center; you can also access it through a link on the International Crane Foundation’s whooping crane page.

Captive Whooping Crane Populations

A new tool was added to the efforts to help the whooping crane species survive in 1967 when a captive breeding program was put in place at the USFWS Patuxent Wildlife Research Center in Maryland.  The Canadian Wildlife Service and the U.S. Fish and Wildlife Service cooperated to remove single eggs from the nests of wild cranes (nests usually contain two eggs) on their Wood Buffalo NP breeding grounds and transfer them to Patuxent for hatching and raising.

This tray of whooper eggs has just come out of the incubator. The eggs will be examined, candled, and weighed to see how their development is progressing. Eggs lose weight during incubation as the chicks grow and use up yolk and fluid. But if an egg loses too much weight too quickly, it can be helped by special treatments or placed in a separate incubator that has a higher humidity level. (Photo by Nelson Beyer, USGS Patuxent Wildlife Research Center)

By 1975 the cranes that had hatched from the collected eggs, had begun to produce their own first eggs. In 1989 the captive breeding program was expanded to include the International Crane Foundation and in 1992 it expanded to the Calgary Zoo.

Today Patuxent and ICF remain the primary centers of captive breeding. The most recent numbers I could find, are from The Journey North website, dated August 30, 2011, which lists 75 whooping cranes in the captive population at Patuxent, including 15 breeding pair, and 37 cranes at ICF with 11 breeding pair.  Six breeding pair are listed at the Devonian  Wildlife conservation Center in Calgary, and there were also 1 breeding pair at the San Antonio Zoo, and 2 at the Audubon Species Survival Center in New Orleans.

USGS employee training baby whooping cranes to follow ultralight aircraft.
(Paul K. Cascio photographer USGS Multimedia Gallery)

The Experimental Populations

Once the captive breeding programs were well-established, the efforts for preservation of the whooping crane species shifted into a new gear.  The focus became all about restoring some of the captive-raised chicks into the wild.  But how?

Much thinking and experimentation has gone into these efforts. In their 1996 report (linked to above) Archibald and Meine wrote, “Teaching migration to young whooping cranes continues to be the most significant barrier . . .” to reestablishing whooping cranes in the wild.

Since then the method of leading an annual class of crane chicks from Wisconsin to Florida via ultralight aircraft has been perfected, and has become a major factor in building an Eastern Migratory Population of 100 birds. Although the EMP flock has – as yet – had little breeding success, it continues to grow through ultralight-led chicks. That method is now being supplemented with releasing captive-raised chicks with older cranes, too.

Ultralight training of juvenile whooping cranes in Wisconsin. (Photo courtesy, WCEP)

In addition to this one quite successful – if incomplete – re-introduction of whooping cranes in Eastern North America, the partners of WCEP continue with efforts to establish a non-migrating flock in the wild. From 1993 – 2004, the Florida Fish and Wildlife Conservation Committee worked with WCEP to introduce a non-migrating flock in central Florida, but problems with drought, predators, and reproduction have brought an end to the release of new cranes into this project. Since 2011 the focus for developing a non-migrating flock of whooping cranes has shifted to the wetlands of Louisiana. In partnership with the Louisiana Department of Wildlife and Fisheries, the fourth cohort of juvenile whooping cranes from Patuxent was released at the White Lakes Wetlands Conservation Area early this year.

A class photo! The entire gang of adolescent whooping crane chicks together at the USGS Patuxent Wildlife Research Center in Laurel, Md. The chicks, hatched and raised by USGS caretakers, are being released into the wild in Louisiana in February 2011. It is a milestone for the state and for the birds, which have not lived in the state since the 1950s. (Photo courtesy USGS)