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Forty-spots can now rest assured

June 6, 2021 Don Knowler

Like customers in an up-market beds and bedding store, forty-spotted pardalotes have been presented with a range of home comforts to make life a little more comfortable.
The forty-spot initiative is not just about the supply of soft bedding, though. The bedding contains a pesticide which is ridding the pardalote chicks of a parasitic fly decimating their number.
Found only in Tasmania, the forty-spotted pardalote numbers probably no more than 1500 birds, most found in colonies on Bruny Island. The population has declined because of the clearance and fragmentation of their favoured white-gum habitat. Other threats have emerged in recent years, including widespread parasitisation of nestlings by insect larvae.
I became aware of the parasite problem a few years back when I helped a Canadian biologist, Amanda Edworthy, catch forty-spots on Bruny so she could take blood samples as part of a wider survey of their genetic diversity and general health.
Amanda had set out to control the pest infestation by spraying an insecticide harmless to birds in nesting boxes. and now a researcher taking over the forty-spot research, Brazilian Fernanda Alves, has found a less labour-intensive method of insect control.
Because pardalotes line their nests with feathers, Fernanda and her team have devised a special wire dispenser loaded with sterilised feathers that are normally sold by pet shops to caged-bird enthusiasts. These chicken feathers are in turn laced with insecticide so the pardalotes carry out their own fumigation when they collect and lay them in nest boxes.
On my initial visit to Bruny, it was a shock to hold tiny pardalote chicks in my hand and see the larvae of screw-worm fly attached to the featherless nestlings.
The larvae burrow into the skin and feed on the chick’s blood. About nine out of 10 pardalote nestlings die as a result of anaemia but under the latest program 95 per cent of chicks in treated nests survived last summer’s breeding season.
The day I met Fernanda after she had taken over from her predecessor she was busy climbing white gums to help out with swift parrot conservation on Bruny, but she managed to take a time-out to discuss pardalotes.
Parasites were something most birds dealt with but with incredibly low pardalote numbers and high rates of infestation at sites on North Bruny, it meant the pests represented a major problem for a species already struggling to survive.
The dispensers stacked with feathers are hung near nest boxes, and said Fernanda: “They give the pardalotes a hand with not only nest building, at the same time it fixes their fly problem.
“It’s a way of helping the pardalotes to help themselves,” added Fernanda, a PhD candidate with Australia National University, which is overseeing the program.
As with the swift parrot, intensive surveys have revealed the forty-spot population is far smaller than previously thought. The bedding initiative gives the species new hope.

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