Sarah Bond & Tim Guilford, OxNav
Elegant, elusive, and especially British birds: Manx shearwaters (Puffinus puffinus, affectionately known as manxies) breed almost exclusively on islands off the west coast of Britain and Ireland. Prime amongst the colonies are Skomer and Skokholm islands, managed by the WTSWW and home to the largest concentrated breeding colony of Manx shearwaters on earth. Most people will never have seen them.
Why? Manx shearwaters are highly pelagic (they spend most of their lives far out to sea), only coming on land to breed, in burrows underground, and then only at night. To most of us they are largely invisible. And yet, this enigmatic bird is perhaps one of the most under-appreciated in the UK, especially during the spectacular fledgling period. On dark nights during September every year, whilst our seabird islands are largely silent with most species having long finished breeding, the shearwater colonies come alive. Thousands of fledgling shearwaters emerge from their myriad burrow nests, and for multiple nights in a row exercise their wings balanced atop prominent “launch rocks”, view the stars (who knows), and contemplate their first great migration to their wintering grounds off the coast of Argentina. After sloughing off their final vestiges of down, having been abandoned by their parents weeks before, their development from grey fluff-and-fat balls to graceful ocean wanderers is complete, and the youngsters commence the most dangerous journey of their lives. We think that only about a quarter of shearwaters will survive to breed back at their natal colony four or five years later, with earlier and heavier (better fed) fledglings faring best. Many are wrecked after attraction to artificial lights, but surely that first 10 000km journey (which we think may be undertaken fairly directly) must impose great energetic demands and pose a significant risk for the less well nourished. We’re still uncovering the secrets of the immature shearwater’s pre-breeding years after that first migration, but our early tracking results suggest that many may not even venture back to northern latitudes in the first couple of years, instead exploring the waters of eastern South America and the Carribbean. Eventually, though, the survivors will return to choose a mate, secure or dig a nesting burrow, and produce their first single offspring: the first of many during their extraordinary long lives.
You can witness the fledgling spectacle for yourself by visiting Skomer during “shearwater week”. For more information click here, or contact 01656 724100.
Below is an image of a Manx Shearwater chick.