PhD Study leaves no stone unturned

Aurelie Labbe searches for babies as the parents circle. Pictures: Louise White www.communitypix.com.au d413787
Aurelie Labbe searches for babies as the parents circle. Pictures: Louise White www.communitypix.com.au d413787

Murdoch University PhD student Aurelie Labbe is nine months into the study, which she is completing as part of her three-year PhD program in marine biology.

Bridled terns are a common seabird species in Western Australia and first colonised Penguin Island as a breeding ground in 1952, returning most years since to nest and rear their chicks.

Penguin Island is currently the only field study site for this research, and Ms Labbe said bridled terns would have originally chosen the island as a breeding site as they prefered to breed in colonies on rocky islands.

‘Some of the birds in this colony are more than 30 years old,’ she said.

‘Their breeding range has expanded (in recent years) because of climate change and this study is to look for any indication of how other bird species may cope in warmer conditions.

‘(The colony) is doing very well, they are a tropical species and unbelievably, they benefit from climate change because they love warmer, tropical conditions.’

About 4000 breeding pairs inhabit the island between November and May, and then return to the Celebes Sea near Indonesia for the remaining months when local weather gets cooler.

Ms Labbe travels to the island three times a week to weigh chicks and measure their wingspans, collating her data to get an overall picture of how the chicks cope in the climate and if there are any changes that would hinder or help other species.

Unfortunately, a small number of chicks died over the Christmas period and Ms Labbe wasn’t sure if the deaths were down to natural causes or outside factors, such as predators like rats, which decimated a whole nesting season some years ago, or visitors to the island.

‘A number of people were seen throwing stones at the birds and chicks and I don’t know if this contributed,’ she said. ‘The eggs are well camouflaged and unless you have a trained eye, it is hard to tell the difference between an egg or a rock, so we lose some.

‘This is detrimental to the colony because they only lay one egg (per nesting season).’

Once the chicks are able to fly and fend for themselves, they are taught to fish and the colony returns as a group to the Celebes Sea.

The study is also looking at whether older breeding pairs are better at rearing chicks.

Ms Labbe will complete her study in April or May, and plans to repeat the study from September to May 2015 for statistical accuracy.