Why does one of the world’s rarest birds spend so much of its time in the Channel Islands?

Balearic shearwater (2). Photo by Regis Perdriat

Today, 197 of the world’s rarest birds are considered to be Critically Endangered (species facing an extremely high risk of extinction in the wild). In the Channel Islands we often hear a lot about these birds as several are the subject of conservation programmes run from Jersey’s Durrell; however, much less well known is that one of these extremely threatened species choses to spend a very important part of its year in the waters around our islands.

Only an estimated 9,000-13,000 adult Balearic shearwaters exist. This seabird breeds only in the Mediterranean’s Balearic Islands of Mallorca, Cabrera, Menorca, Ibiza and Formentera. It is then, rather surprising, perhaps, that, traditionally, after the breeding season, between late May and the end of July, the majority of the global population passed through the Strait of Gibraltar and into the Atlantic, dispersing northwards to post-breeding grounds in the Bay of Biscay and Iberian coast, where they undergo their annual flight-feather moult

During some years, warmer than usual sea surface temperatures led to a northward shift, presumably following their fish prey. Birds were seen along the UK’s coastline and often in good numbers in the Channel Islands. Most individuals return to the Mediterranean in the autumn, with return passage beginning in September and peaking in October-November, although late individuals are still recorded passing Gibraltar between December and April.

In Jersey we typically saw a handful of Balearics during the year except in rare, exceptional years like 1985 when 603 were recorded. That was until recently. In 2009, 320 were recorded during the year and numbers have been steadily increasing since then: there were 845 in 2011, 3,181 in 2012 and 3,556 last year. This year, so far there have been “thousands” in our waters although they’ve been forming mixed flocks with non-breeding Manx shearwaters, northern birds that may have not been in good condition following the spring storms.

Balearic shearwater 1991-2013

Big Balearic shearwaters flocks are being recorded from Guernsey too and birds are being encountered at sea throughout our area. What does this mean for the shearwater? Well, we may now be responsible the greater part of the population of a very rare bird for a significant part of its year. Each year, now. Our record, unfortunately, isn’t that good for the common species!  Let’s make sure we look after the Balearic shearwater as the whole world may now be watching us!

You can download the International Species Action Plan for the Balearic shearwater and other action plans for European bird species here

Balearic shearwater. Photo by Regis Perdriat