Tiny solutions for tiny survivors

Australia’s endemic species aren’t doing so hot, but an endangered songbird—the Forty-spotted pardalote—could get a big break thanks to researchers, a bird-friendly insecticide, and cotton balls.

Since 1997, the Forty-spotted pardalote, an aptly named white-spotted bird native to Southeast Tasmania, have lost 60 percent of their population. Why? No one really knows, but researchers are trying to solve the puzzle in time to save the species from outright extinction.

One of these dedicated individuals, Amanda Edworthy, a Canadian just finishing up her PhD at the National University of Australia, may have uncovered a major factor behind the little bird’s woes. And putting a stop to the threat may be easier than anticipated.

Edworthy found parasitic flies eggs in 88 percent of the forty-spotted nests she surveyed, and when they hatch, the ensuing maggots burrow under chick’s skin and begin to gorge on blood.

‘We saw these weird lumps on chicks, so got a wildlife vet, and when she squeezed these deformities for samples, out wriggled fat maggots,’ says Edworthy. ‘And they’re big suckers, some we saw were half the size of the bird they were feasting on.’

Forty-spot nestlings infected with parasitic fly larvae. Photo by
Forty-spot nestlings infected with parasitic fly larvae.
Photo by Amanda Edworthy

Parasites generally pull some pretty nasty tricks to get their way, but decimating their host’s population at the rates Edworthy found—75 percent—isn’t usually on the agenda. Eating through all their hosts would leave the parasite’s future generations high and dry. Foreign or introduced species can wreak havoc on native host populations, but in this case, the fly Edworthy found was native to Tasmania.

‘Word on the block is smart parasites don’t often kill this many of their hosts,’ says Edworthy. ‘Something has gone wrong, or has changed the relationship, but we really don’t know what.’

Even without knowing the reason for the imbalance, Edworthy thinks big strides can be made towards clearing the bloodsuckers from forty-spot nests. In the Galapagos, Darwin’s finches are facing similar population devastation, thanks to an invasive fly parasite, and researchers have designed a fairly simplistic solution. Douse some cotton wads with bird-safe pesticides, and let the birds do the rest.

‘When we’ve done some basic experiments, nests with incorporated cotton had 90 percent fledge rates, in those without them, only 15 percent made it out of the nest alive.’

That’s a big turnaround, but Edworthy says it will be a year or two before real trials will begin, placing the chemical-laced cotton in a cage in the forest for the birds to take from similar to Galapagos projects. This really needs to happen—at last count there were only 1,000 or so of the little songbirds left in the wild.

But once these stations are in place, it shouldn’t take much persuading for the birds to take home the super-soft lining. Edworthy says she’s dropped cotton-samples on the forest floor from time to time, and the little birds snatched them up in most cases.