Busy Little Winter Visitors… Fairy Prions

By Kieth Hutton on August 23, 2013 in Other

Photo: Tobias Hayashi

Prions are closely related to albatrosses, petrels and shearwaters and are also known as whale birds. They are winter visitors off the coast in the Sydney region and at least five species have been recorded off New South Wales. All of them are blue-grey above and white below, with black-tipped tails and a distinct dark open ‘M’ mark across the extended wings and back. They are smaller than most other sea birds and usually stay well out over the ocean.

When the weather is foul and there are dangerous surf warnings in force they come closer in to shore, bobbing up and down and fluttering about close to the surface of the water in among the more experienced surfers who have not been discouraged by the adverse weather conditions. I heard of a few at Bronte recently, behind the reef where the penguins feed in summer, and others inside Gordon’s Bay where the weather is less wild. The most frequent visitors are Fairy Prions, which breed on islands off the coast of Tasmania and Victoria. Those that nest outside Australia are scarcer.

Prions generally are very difficult to differentiate from one another. Fairy Prions are the bluest, and a combination of pale head and broad black tail tip distinguish them from other species that have been recorded in the Sydney region. In windy conditions they fly in loose flocks close to the water at high speed on fixed wings, twisting and turning, conspicuous white undersides alternating with pale blue-grey upperparts, obvious one second then almost invisible against dark waves the next.

Prions have circumpolar distribution in the southern oceans where they breed in colonies on islands in summer and wander extensively for the remainder of the year. Their preferred habitat and their only feeding area is the open ocean, usually far from land.

All prions are adapted for feeding on a variety of small marine animals and little fish close to the water surface. Their bills, which are designed to separate seawater from a mouthful of food – a bit like Humpback Whales – vary in size and shape, and this defines which prey different species select. They are busy little birds and feeding behaviour is so characteristic that it is a good way of recognising them out at sea. Individuals bounce over the ocean, tilting and flitting from wave to wave and hydroplaning with spread wings, sometimes with heads under water. At other times they submerge using half-closed wings as paddles, then pop up to swallow captured food items on the surface.

At nesting colonies prions suffer from predation by natural enemies such as skuas and exotic predators including feral cats and rats. Degradation and erosion of habitat on some islands has resulted from introduction of rabbits, pigs and cattle, and removal or eradication of these results in improved breeding success. In winter many prions die in storms and are washed up on the shore. Despite these threats, global populations appear stable and prions remain among the most numerous and widespread seabirds in the southern hemisphere.