European Storm-petrel (Hydrobates pelagicus) Science Article 5
Storm Petrels Hydrobates pelagicus are notoriously difficult to census because they nest in burrows and crevices, they visit land at night, and colonies are usually visited by large numbers of itinerant pre-breeding birds (Ratcliffe et al 1998, Insley et al 2002). The Spanish Storm Petrel population has been estimated at 5,005-7,900 breeding pairs (bp) spread over the Cantabrian Sea (Galicia 10-240 bp, Asturias 412-805 bp, Cantabria 93-325 bp, Bizkaia 63-220 bp), the Mediterranean coast (Alicante 555-685 bp, Murcia 360-544 bp, Baleares 2,912-4,064 bp) and the Canary Islands (595- 1,000 bp) (Minguez 2003). The difficulty of reaching many nest sites and of conducting capture-recapture studies on islands has meant that most of these population estimates were based only on nests found on accessible faces (Boersma & Groom 1993, Minguez 1994, Minguez & Vigil 1995). To evaluate the accuracy of these estimates and produce better approximations of population size, we carried out a 16-year (1990-2006) ringing project on Aketx Island, which harbours the largest Storm Petrel population of the area (Azkona et al 2006).
Inigo Zuberogoitia, Ainara Azkona et al., Ringing & Migration (2007) 23, 252-254