Lamington National Park
Early European settlers in Australia called rufous fantails "mad fans", because of their wagging, fanned tail and the fact that they never sit still. They chase insects on the wing, whirling and whizzing, making u-turns on a vertical plane, zooming with wings in arcs, their tails ablaze with a circle of rufous orange. They look like pinwheels twisting through the forest on the wind."They’re incredibly high energy, hyper; they rarely sit in one place for more than a second," says Lindsey Nietmann, who is writing a PhD with the University of of Washington on the birds.
Rufous fantails (Rhipidura rufifrons) have cousins all over the Pacific. In fact, subspecies of these twitchy creatures are dispersed across Papua New Guinea, the Solomon Islands and the Mariana Islands.They used to be on Guam, a tiny island in the ocean between Papua New Guinea and Japan, until disaster, in the form of the brown tree snake, struck. After World War II, at least one pregnant tree snake stowed away on a US military shipment of scrap metal from Manus Island to Guam. Guam has no native reptilian predators. The snakes flourished and ate every single bird they could get their fangs on. At their peak there were 100 snakes per hectare, leading to the extinction of all but one of Guam’s bird species. One of the birds that perished was a subspecies of the rufous fantail, and will never exist again.
At Iluka on the NSW north coast lives one of the two subspecies of rufous fantail in Australia. The same species of snake that was accidentally released on Guam lurks in the forest, but the Iluka fantails show no signs of imminent serpentine-caused extinction. In fact, the area has the highest density of rufous fantails that Ms Nietmann has seen in Australia; she estimates two to four individuals per hectare during peak breeding season.
Ms Nietmann is seeking to understand why the Australian birds survive when the rufous fantails of Guam were eaten into extinction. To do this, she is studying both the Iluka fantails and their cousins on Rota, an island just north of Guam that has only avian predators. She is monitoring the breeding population’s nest-building activities, their egg laying, how many chicks they have, how much food they feed each chick and even how long the young stay in the nest.
Any one of these small details could contribute to the birds’ continuing survival. "If you think about the chances of a predator finding the nest, those chances are much higher if the nestlings are in the nest for longer," Ms Nietmann says. "And indeed, they’re in the nest on average on Rota for two or three days longer than they are here." Those two or three days could be the difference between getting eaten or being able to flee a threat. It’s possible that Australian rufous fantails have evolved to get their kids out of the nest quickly in response to the plethora of predation threats.
But it could also be that rufous fantails of Australia have selected, over thousands of years, for a bit of lateral thinking — perhaps they’re more canny when it comes to avoiding getting eaten. Ms Nietmann is testing the predator awareness of the fantails by presenting them with known and novel predators to see how they react. These include a yellow footed antechinus (a known predator in the area) and a chipmunk (from North America, which the fantails will never have seen before). It’s a bizarre sight, watching a taxidermied chipmunk slide towards a nest on a piece of plastic pipe in the middle of the Australian rainforest, but Ms Nietmann believes her study could explain the species’ survival. After all, if you can tell that a chipmunk is murderous straight away, it gives you a chance to take evasive action and, over time, save your species.
Credit: Ann Jones ABC Radio “Off Track”
