The Australian outback is the driest place on the hottest and driest continent on the planet. It is a place you might expect to see kangaroos but certainly not waterbirds. Yet once every ten years or so, heavy rains pour into dried-up river beds and flow inland to create an oasis in the scorching heart of the desert. In a typical flood year, 100,000 pelicans – a third of Australia’s total population – arrive for the event. Abandoning the sea, they leave their coastal homes and journey more than a thousand miles inland to Lake Eyre to feast on an abundance of fish and brine shrimp created by the floods. The bounty of the lake provides a perfect place to breed and raise their families, even in the middle of one of the most inhospitable places on Earth. But much about their lives and their journey remains a mystery that researchers are only now beginning to unravel.
Using DNA studies of bone and egg fragments to trace the history of the birds, tagging young birds to trace their modern movements, and conducting comparative studies of coastal and desert pelicans, Nature examines the secret life of Australia’s nomadic pelicans in Outback Pelicans.
Australian pelicans are large birds, big even by pelican standards. Adult birds need four pounds of fish a day just to stay alive, and are typically found near harbors, where the fish are easy to come by. Why would these birds they leave the coast and fly into a desolate wilderness? What triggers the movements of these thousands of birds? And how do they find their way?
At 50 feet below sea level, Lake Eyre is the lowest point in Australia and the biggest salt pan on Earth, covering an area the size of Texas, Oklahoma and New Mexico combined. Ninety percent of the time, it is a blistering, barren place. But when the rains bring floods, Lake Eyre miraculously brims with life, creating a brief window of opportunity for pelicans. They must make good use of the time they have before the waters recede.
The first priority for the arriving birds is to find a new partner, since pelicans don’t mate for life. Courtship displays include bright new colors on their distinctive pouched bills to attract the attention of potential mates, followed by “pouch rippling” and bill clapping. Partners and nest sites are chosen, and two eggs are laid, with both parents sharing incubation duties for a month.
The chicks are fed regurgitated food at first, and then graduate to pieces of food plucked from their parents’ gullets. How the parents survive having their chicks heads stuck right down their throats is one mystery. The other is what possesses the chicks when their parents are finally able to break free. Nobody really knows why, but the chicks throw tantrums that simply must be seen to be believed.
Young birds gather together in large crèches to tone their muscles and test their wings, preparing to fledge. When they do, it’s unclear where they will go, and whether they will return. It’s possible that their test flights over the landscape and their highly developed visual senses are helping them to create a mental map that will guide them back as adults to breed. No one knows for sure.
Dr. Greg Johnston, of the University of South Australia, monitors the Lake Eyre population from the moment they arrive, hoping to glean clues from them about how the pelicans are able to make such good use of the limited water resources here. Their presence serves as a good indicator of the relative health of the outback ecosystem. And good water management will help to ensure that their populations remain healthy for years to come.
After a few months, the water in Lake Eyre evaporates and recedes, the salt is concentrated, and the desert reclaims itself. Young outback pelicans depart. Where they all go is still a mystery but history has shown that outback pelicans will arrive again when the waters return and the lake reappears.
Nature’s Outback Pelicans is a Production of Tindale Road Films and Wild Fury. Produced by Tina Dalton. Nature is a production of THIRTEEN in association with WNET for PBS. Fred Kaufman is Executive Producer. William Grant is Executive-in-Charge.