These Extreme Desert Nomads Set Records for Migrating Birds

Desert water bird sounds like an oxymoron. But some species, including the Australian banded stilt, make this peculiar lifestyle work. The stilt—which has the posture of a flamingo, the palate of a penguin and the long, thin beak of a hummingbird—spends most of its time on coastal beaches. But when it’s time to breed, it travels to remote salt lakes in Australia’s harsh interior. Thousands of banded stilts gather at those ephemeral water bodies, often just days after the rains arrive. There, they break into pairs and get to work producing young.

Those trips to the Outback, it turns out, are a record-setter for all desert water birds. According to a new study published in Biology Letters, banded stilts can cover up to 1,350 miles in just two and a half days, meaning their epic breeding journey is at least twice as long and twice as quickly traversed as those of similar species.

Researchers at Deakin University discovered the stilt’s abilities while trying to tease out more about the bird’s migration patterns. Unlike most of their feathered relatives, the banded stilt and other desert water birds do not have a set time when they head to the breeding grounds. Instead, their trips depend completely on the whims of nature—specifically, rain. Due to the remoteness of the harsh landscapes where the stilt prefers to raise its young, scientists do not know much at all about its adaptations to desert life. “In particular, the mechanisms used by banded stilt to detect and navigate to these waterbodies are completely unknown, as are the speeds, distances and coordination of flights,” the researchers write.

The authors used satellite transmitters to track the movements of 21 banded stilts over a period of 196 days. The team captured the birds at three sites in South Australia, one of the most arid parts of the continent. They found most of the birds on the coast, but seven of them came from Lake Harry, an on-again, off-again saltwater wetland located miles from the sea.

The banded stilts’ movements were completely irregular and non-seasonal, they found. Instead, the birds followed the water, moving inland after a good rainfall and then leaving as the site dried up. The extreme nature of some of these movement patterns shocked the team. The birds traversed hundreds or even thousands of miles to get to or from salt lakes, often covering those distances in just a couple days. At one point, two birds left the same coastal spot, and then took wildly different routes of more than 1,000 miles, only to eventually reach the same inland refuge. 

The researchers still do not know how the birds manage to locate those land-locked nesting sites, or what clues they are homing in on to get their timing right. The scientists suggest that the stilts are “possibly detecting the passage of these distant weather systems via low-frequency sound, temperature or pressure gradients.” It could even be something to do with their sense of smell. For now, though, the team has no idea.

What they are certain of is that the banded stilt’s lifestyle is an exceptional case among an already exceptional group of birds. “This species indeed epitomizes extreme nomadism,” the authors conclude, with a hint of reverence. “However, there is still much to learn.”  

Rachel Nuwer | | READ MORE

Rachel Nuwer is a freelance science writer based in Brooklyn.