Sunday, 14 October 2012

Gouldian breeding soars thanks to artificial nests

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GouldianFinch nests“Simply by putting the boxes there we’ve got the birds back in the areas they haven’t been found for very many years”—Dr Pryke. Image: Dr Sarah PrykeSYDNEY University ornithologists are enhancing the breeding rates of endangered Gouldian finches (Erythrura gouldiae) in the Ord Valley near Wyndham.

Ornithologist Dr Sarah Pryke says the program uses specialised nesting boxes.

She says lack of nesting hollows severely affects the species’ fertility—before the program started she often observed a dozen breeding pairs competing for a single nesting hollow.

“Gouldian finches are very nest site-restricted, so there’s actually very few hollows in the environment which are suitable for their nests, mainly because of fires in the area,” she says.

“Most eucalypt trees have to be at least 80, but usually about 100 to 120 years old to produce a hollow that’s actually useable for a Gouldian finch nest site.”

She says the program began five years ago.

“We started in the populations where the Gouldian finches definitely were breeding already and … saturated the habitat with these nest boxes,” she says.

“It’s been shown now that simply … putting up these nest boxes in the environment would increase the populations dramatically.

“Often … less than about 40 per cent of the population would actually breed, but with these boxes in place we find over 90 per cent are breeding.”

Later, the team started installing boxes in different locations they judged to be perfect Gouldian finch habitats.

“It seems that they [the birds] are not there because there is just not enough hollows in the environment,” she says.

“Simply by putting the boxes there we’ve got the birds back in the areas they haven’t been found for very many years.”

The boxes are rain and cyclone proof and made from salvaged hollow tree branches.

“We don’t cut down trees or hollows,” she says.

“Many have come from the Ord irrigation, the Stage II expansion project where they’ve been doing land clearing.

“They have to be very specific diameters and thicknesses … [the] birds are really fussy.”

“It really controls heat and humidity and things as well as being a good clean space so the birds are actually producing about twice as many fledgelings than they are in natural hollows,” she says.

She says the birds prefer the artificial hollows to natural ones.

“We’ve had nearly no predation, it’s less than three per cent which is incredibly low.”

She says almost all of the chicks survive to maturity in the custom-built hollows, whereas more than half tend to die in nature.

This story pertains to deliveries in theme 3 of the Kimberley Science and Conservation Strategy.

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