Since then, Dr. Brandis said, she has received more than 720 envelopes from about 175 senders, 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,” Dr. Brandis said. But when the water recedes, the birds disband. “You don’t see them again for years,” she said.