Seeing Where Birds Flock Together

SYDNEY, Australia — One day in April 2016, Kate Brandis opened a weathered envelope, mailed to her from suburban Sydney. Instead of a letter inside, she found the feathers of an Australian white ibis. A day or so later, another envelope arrived, stuffed with more feathers. In the days following, more began to come.

Soon Brandis, who is a research fellow at the University of New South Wales’s Center for Ecosystem Science, was receiving three to four envelopes a day containing the feathers of birds from across Australia, including those of pelicans, wood ducks, cormorants, herons and spoonbills.

“It was really exciting,” Brandis said, sitting in her office at the Australian Nuclear Science and Technology Organization in Sydney in January. Two years before, she had put out a call to the public to send her fallen feathers of wetland birds so she could analyze where they came from, in an effort to map how the birds are moving between the country’s disappearing wetlands.

Since then, Brandis said, she has received more than 720 envelopes from about 175 people, filled with thousands of feathers from about 480 locations across Australia.

Wetlands — which include swamps, marshes, lakes, mud flats and bogs — are biodiverse ecosystems that can improve the quality of water and mitigate damage from flooding and pollution.

But since the beginning of the 20th century, some estimates say, more than half the world’s wetlands have been lost, largely because of human activities.

In Australia, some regions have lost 70 percent or more of their wetlands, often as water is diverted for irrigation.

Now, the impacts of climate change — which can include less rainfall in some areas, changing river flows and flood patterns, and potential saltwater intrusion into inland bodies of water — are further threatening some of Australia’s wetlands and the birds that rely on them for breeding.

“When our floodplains flood, which is only every couple of years, these birds come together in the hundreds of thousands to breed,” Brandis said. But when the water recedes, the birds disband. “You don’t see them again for years,” she said.

The birds’ mysterious movements have long baffled Brandis and others in her field: Where do the birds come from, and where do they go afterward? “Because we don’t track our birds, we have no idea,” she said.

Traditional tracking methods, like banding birds, have not fared well in Australia. Since 1955, researchers have banded almost 57,000 straw-necked ibises. Just 15 of them were seen alive again. (An additional 360 were found dead.) In part, the low resighting numbers can be explained by the fact that many birds, like the ibis, have a high mortality rate. Another factor is simply Australia’s size: Inland birds often go to places where people do not.

For that reason, Corrie Kemp, a 73-year-old retiree from Queanbeyan, New South Wales, made a special effort to collect feathers for Brandis’ project from among the most remote corners of Australia, in western Queensland.

“We made a point of going places where no other people where going,” Kemp said, adding that she and her husband, Peter, had devoted an entire three-month trip to collecting feathers, during which she kept a diary of her discoveries and often corresponded with Brandis.

In Brandis’ office, gray, black and glossy plumes have been filed into letter-size yellow envelopes, neatly stacked on her desk. Collecting the feathers was easy. “It’s untangling the mess of data that is the tricky part,” she said.

Bird feathers, like human hair and nails, are made of a protein called keratin. As the feathers grow, the keratin keeps a record of the bird’s diet, much like the rings of a tree. By analyzing a section of a feather, Brandis and her team can get a snapshot of the bird’s diet while the feather was developing.

Feathers from chicks, which have spent their entire lives at one wetland, are particularly useful to researchers, providing what Brandis and her team call a “fingerprint” of each place. By comparing the diet record of adult feathers against this information, researchers hope to map which wetlands the birds have been using, and how healthy those wetlands are.

The information could help prioritize wetlands for protection and management. Since 1971, 65 Australian wetlands have been designated as significant under the Ramsar Convention, an international conservation treaty. “It puts even more pressure on wetland managers to get it right,” Brandis said, adding that she was hoping to have results by the end of the year. Previous studies have used similar techniques to track monarch butterflies in North America and birds in Europe, but Brandis is the first to do this kind of work in Australia. “It’s very ambitious and it’s kind of neat,” said Keith A. Hobson, a professor of biological and geological sciences at Western University in Canada, who led the study of monarchs in 2004. Hobson said he liked the idea of using birds to learn more about wetlands, rather than the other way around. “It’s flipping it on its head,” he said.

At the nuclear agency, researchers are using similar techniques to identify the origins of fish and prawns that they suspect may be falsely labeled locally farmed or caught.

Working with the Taronga Zoo in suburban Sydney, Brandis has also tested the quills of captive and wild echidnas, in the hope of developing a similar tool that could identify animals that have been poached. (Echidnas are difficult to breed in captivity, yet dozens of purportedly captive-bred animals are exported every year.)

Brandis said the possibilities were endless when studying animals’ tissue for clues about their environments, their habits and their origins. “It’s like the tip of the iceberg,” she said.

Meanwhile, for citizen scientists like Kemp and her husband, the feather-mapping project has inspired a new passion. “We weren’t really into birds,” Kemp said. “But now, we are.”