South Polar Skuas at a Glance
I’ve been through the entire list of Polar problems. I knew it would be hard, but it’s harder than I ever thought it would be. I’ve suffered from blisters, a high-altitude cough, frost nip, and I even managed to break a ski they told me was unbreakable.
-Lewis Clarke
Over these past weeks I’ve been doing seabird surveys off Galicia, I’ve been able to study loads of big Skuas, what made me aware of how hard, and sometimes how easy, South Polar Skua identification can get. The constant SW-W winds I got during the almost 3 weeks I spent offshore helped big numbers of seabirds gathering together around Fisterra area, feeding on the rich upwelling produced by those oceanic conditions. Great Skuas were particularly abundant, with up to 120 individuals counted together feeding on our discards. Among the thousands seen, 3 South Polar Skuas (all aged as 2ndcycle+) stole the show, given the species is still considered a mega in this side of the Atlantic.
All the birds behaved the same way, keeping larger distances towards the boat than Great Skuas and offering just a couple of close-by glides. The identification process, therefore, needs to be quick, especially if photos are still required. With such a big number of ‘big skuas’ following the boat, it’s worth to dismiss as many obvious birds as possible and to do it rapidly, so we don’t miss a chance with the actual candidates. I want to make clear first that I’m not very experienced with SPS: I’ve just seen 4 individuals in two consecutive years off Galicia (plus 2 probable SPS back in 2011 and 2012), but I thought it could be useful for some to share here a captioned collection of ‘big-skuas’ photos, starting with the most obvious Great and ending with the real SPS, trying to depict pretty much everything in between. Let’s start by the
South Polar Skuas are probably much regular in Europe than we think and feels like identification is still in a work in progress stage. Although there’s been some big steps during the last years (e.g. Newell, et al. 2012), some individuals are still causing trouble, especially from land but also when seen at decent distances. Although there’s already a lot of material relative to SPS in the North Atlantic (of course especially from the American side), I feel there isn’t much on dark juvenile/2cy Great Skua yet. Despite these tricky plumages prevent SPS from being safely identified from very big distances, there is a good number of features that are most-likely diagnostic when they can be actually assessed.
I want to thank Daniel López-Velasco for the very interesting conversations on this subject we’ve shared over the last years and Martí Franch for letting me include his 2011 bird and also for encouraging me to write this post.