European Storm-petrel Hydrobates pelagicus

Studying Stormies in Portugal - would you like to help during June 2011? See our Stormies blog.

The European Storm-petrel (Hydrobates pelagicus) is the smallest and most mysterious of Europe's ocean-going birds. Weighing on average 25 g, no more than a sparrow or a large box of matches, it spends its life out at sea, coming to land only to breed in crevices on rocky coasts. Even then it is rarely seen, as it leaves the nest at night to avoid aerial predators.

A boat trip can offer a better chance to see them. Storm-petrels often feed behind fishing trawlers. They flutter just above the waves, their legs dangling into the water ("petrel" may have origins in St Peter walking on water), picking off crustaceans and other small marine organisms.

Petrels are known to migrate massive distances. The Wilson's Storm-petrel, for example, performs figures of eight each year between the sub-Arctic and its Antarctic breeding grounds. The annual migration of the European Storm-petrel is hardly less impressive, traveling as it does between the Indian or Atlantic Oceans off southern Africa, and its nest sites in the North Atlantic, sometimes at speeds of 200 km (125 miles) per day. What distances must be clocked up in its typical lifespan of thirty years or so!

Rob Thomas and Emma Fisher releasing the 100th European Storm-petrel caught in 2003 by A Rocha Portugal.

Still, at least the very first years are less demanding. The young birds stay around in the southern hemisphere, and thereafter wander along the coasts of Africa and Europe prospecting for breeding territories. It is some of these birds that unexpectedly hear and are attracted to the sound of birds of their own kind calling from the base of a cliff on the south coast of Portugal. Here a small team from Cruzinha are camped for the night at this impressive natural setting, huddled around thermos flasks, rather deafened by the amplified tape lure, and peering through the gloom at the arrangement of mist nests around them. It doesn't help that "stormies" are mostly black, their white rumps not very visible until in the hand.

Over the fourteen years of this A Rocha study, some three thousand petrels have in this way been caught, studied and released again into the night. A remarkable proportion (about 8%) have already been ringed elsewhere. Two other species have also been caught: a Swinhoe's Storm-petrel and a Madeiran Storm-petrel. It is exciting fieldwork. It is also a unique scientific opportunity to study the petrels away from their breeding grounds and to better understand how these tiny birds are designed to live an oceanic life. Currently, in research now led by Dr Rob Thomas of Cardiff University, we are questioning how climate change might affect their survival, in relation to sea surface temperatures and food availability. The study is topical, and not a little rewarding for its close encounters with these wonderful little beings.

Will Simonson
Originally in A Rocha International News
Issue 34, April 2004