New Avian Database to Help in Bird Species Survival

Sharon Guynup
National Geographic Today

July 24, 2003

The large egg moved in the incubator at the Kellogg Bird Sanctuary in Hickory Corners, Michigan. A crack appeared, growing slowly until a pink beak and then a wet, silvery-grey head emerged—a trumpeter swan cygnet.

This hatchling is just one of hundreds of its kind that have been incubated and raised in captivity for release into North America's wetlands. Most trumpeter swans disappeared from the continent by the turn of the 20th century, hunted for meat and their coveted feathers, which were highly prized for women's hats and pillows.

Reintroduction efforts for these stunning white swans—North America's largest waterfowl—is a huge success story. Since the mid-1980s, 1,903 swans have been released in the Midwest and Canada, swelling the region's population from less than 200 twenty years ago to about 3,500 today.

But back in the 1970s when biologists and wildlife managers struggled to save the nearly-extinct birds, they didn't know how to begin. "We're missing a lot of the basic information on the biology of most animals," said George Amato, director of conservation and science programs at the Bronx-based Wildlife Conservation Society. Scientists know even less about the often-subtle interdependence of ecosystem residents.

The need for that information is urgent. Among birds worldwide, one in eight species is facing extinction because of habitat loss, hunting, pollution and other threats. To reverse this trend, conservationists are breeding certain species and releasing them back into their native neighborhoods.

Creating an Avian Database

But some reintroduction programs are more successful than others. Each attempt involves trial and error and little data on previous reintroductions are available. But now the Avian Reintroduction Database, in development at the Lincoln Park Zoo in Chicago, will help conservationists design future programs based on the lessons of the past by cataloguing information on bird biology, release methods and ecosystems.

Joanne Earnhardt, LPZ's director of conservation biology is spearheading the project. The idea grew out of an effort to save highly endangered Micronesian kingfishers in Guam, where many bird species had been decimated by a brown snake invasion. Earnhardt's colleagues rescued 29 birds off the island, bred and raised them—but now wrestle over how to release them. Two pairs at a time? Five pairs? Or just five males first to see if they survive?

"That's when we decided we wanted to synthesize this information into something people could use," Earnhardt says. A team from the Lincoln Park Zoo began brainstorming the database in 2001, eventually joining forces with the U.S. Fish and Wildlife Service.

"This is an attempt to create a more scientific approach to reintroduction," said Eric Vanderwerf, Hawaiian bird recovery coordinator for the U.S. Fish and Wildlife Service who advises on the database's design.

After combing the scientific literature for papers detailing bird reintroductions, the team searched websites and unearthed unpublished data. They've identified 105 different reintroduced bird species—from New World parrots, the California condor, and the palila (a type of Hawaiian honeycreeper), to Griffon vultures in Europe, the toutouwa (also known as the New Zealand robin) and the Bali starling.

Logging species in at a rate of about 10 per month, the data should be compiled by the end of the year. The database will ultimately be posted on the Web.

The long-term plan is to include other creatures. "We started with birds, but it certainly can be expanded to include mammals and other animals," said Earnhardt. The database will prove a valuable resource as conservationists reevaluate priorities and look for smarter, more cost-effective approaches and tools.

Planning Reintroductions

Had this avian database been in existence in the 1980s, wildlife managers may have taken a different approach with trumpeter swans, using successful reintroductions of Canadian geese as a model.

The database promotes information-sharing. "The way you gather eggs, hatch eggs, and raise young would be transferable between similar birds," said Joe Johnson, chief wildlife biologist at Kellogg Bird Sanctuary. "We had to use a 'shotgun' approach because we didn't know what would work."

Some biologists tried placing trumpeter eggs under surrogate mothers of another species—mute swans—with limited results. Some reared cygnets by leading them around marshlands with a puppet "mother," at a cost of U.S. $500 per swan. Other scientists learned that survival rates jumped from 50 percent to over 70 percent by releasing two-year-olds instead of yearlings.

In any reintroduction, "the first assumption is that you've done the homework to see if reintroduction is a viable strategy," said Steve Thompson, LPZ vice president of conservation and science. Available habitat and safety are important considerations—and whether the species breeds well in captivity.

Then biologists must decide where, when and how to release birds. Some birds are "hard" released: biologists simply open the cage and let them go—a less effective, and less expensive method than "soft" release, where young birds live in a field aviary for some weeks. After release, they are given supplemental food until they adjust to their new surroundings.

Not a Panacea

Peregrine falcons have rebounded dramatically after decades of successful reintroduction. By the 1970s, the birds were nearly wiped out by exposure to the now-banned pesticide DDT. But it took three years for Tom Cade, founding chairman of the Peregrine Fund, to breed the birds at Cornell University in Ithaca, New York. They found that only hand-raised birds, not wild birds, nested in captivity. Now at least 300 pairs nest on buildings, smokestacks and bridges across the region.

By contrast, just 56 wild Attwater's prairie chickens remain. Their Texas grassland habitat has shrunk to less than three percent of its original size. The birds are difficult to breed. Reintroduction has not yet brought them back.

Restoring birds to their homelands is not a panacea. Some birds won't breed in captivity, and for many, there is nowhere left to live. "Clearly, reintroduction is not going to save every endangered species," Johnson said. "We don't have the time, the money, or the knowledge to save every bird on Earth, one at a time. If we want diversity of birds, we better save large chunks of the ecosystems that support them."

There the database has its limits. "It doesn't deal with the human component, the social, economic, or cultural issues like why we shouldn't poach, eat or kill these birds," Earnhardt says.

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