Short-Tailed Shear Waters In The Atlantic Ocean

Short-Tailed Shear Waters In The Atlantic Ocean

- Peter Ryan

The Short-tailed Shearwater Arden-na tenuirostris is one of the world’s most abundant seabirds. Despite only breeding at islands off Tasmania and southern Australia, the total population is of the order of 30 million individuals. Like its close relative the Sooty Shearwater, it is a trans-equatorial migrant, wintering in the North Pacific Ocean and Bering Sea. During the austral summer, the birds travel south to about 60-68°S from the mouth of the Ross Sea to roughly 50°E.

Confusion with Sooty Shearwaters meant that it was only in the 1980s that researchers realised that Short-tailed Shearwaters ventured so far south. The two species are tricky to separate at sea and the presence of Short-tailed Shearwaters in Antarctic waters was only confirmed by examining birds that had died after colliding with research vessels. Initially it was assumed that these birds were non-breeders, but tracking and stable isotope studies in the late 1990s confirmed that breeding birds routinely forage in Antarctic waters.