10 Sep 2015

Fowl smells may prove a friend to native birds

12:19 pm on 10 September 2015

A Kiwi scientist is harnessing the power of scent to detract predators from nesting native birds.

Some 25 million native birds are estimated to be killed each year by introduced predators like cats, rats, possums and stoats, which use their sense of smell to hunt.

A braided river bird nesting.

A braided river bird nesting. Photo: Wikicommons

Landcare Research scientist Dr Grant Norbury will use "generic bird scents" in native bird habitats before the birds are introduced to the areas, to train hungry predators investigating to think there are no rewards to be found, despite smells to the contrary.

"After several weeks, predators will lose interest in investigating the odour and we will have deceived them into thinking that bird odours are no longer a profitable cue for food," Dr Norbury said.

It is not a permanent solution - once the birds have arrived, predators will re-learn that the smells do sometimes result in a reward - but Dr Norbury and his team hope that the approach will give native birds a window in which to breed, unbothered by predators.

This nesting window is often the most vulnerable period for native birds, who are essentially sitting ducks.

"Many of our birds have evolved behaviours that defend them from native avian predators, which hunt mostly by vision, but not from introduced mammals, which hunt mostly by smell," said Dr Norbury.

Dr Grant Norbury

Dr Grant Norbury Photo: Supplied

"This has created a behavioural mismatch between the predators and vulnerable native species, and the results have been devastating."

Australian trials showed that rats lost interest in the smells after just three days, leading to a 60 percent increase in nests' survival rates.

"It's important to realise that native species are mostly secondary prey for ferrets, cats and stoats. Their primary prey are often other introduced species like rabbits, rats or mice.

"This makes it easier to deflect predators' attention away from native species for short periods," he said.

Initial trials are expected to begin next month, followed by field trials on braided river birds early next year in the Mackenzie Country.

The two-year project was granted almost $1 million by the Ministry of Business, Innovation and Employment, among 48 new research proposals.

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