Lots of news to report from Slettnes! We are enjoying much activity at sea, where huge feeding frenzies of gulls (mostly Black-legged Kittiwakes and Herring Gulls) feast on pelagic fish together with Minke Whales and occasionally joined by White-beaked Dolphins, Humpbacks and Fin Whales. Many skuas (including migrating Pomarine and Long-tailed Skuas, plus the locally breeding Arctic Skuas) join the party as well. The Arctic Skuas seem to do very well in obtaining food.
Fox caught red-handed
On land however, things are not going that great for the Arctic Skuas. As reported before, most freshly laid clutches disappear after one or two days. To find out who takes them, we deployed camera traps at skua nests. Although it seems that nests with cameras are less quickly predated as other ones, we managed to capture two Red Foxes in the act of taking skua eggs! See below…
27 years old male Arctic Skua
Yesterday, we captured a male with a somewhat worn metal ring and a ring number that clearly didn’t belong to the series we have used since 2014… It turns out this bird has been ringed on 3 July 1991 as a chick at Slettnes, by Karl-Birger Strann. Actually, it was amongst the very first Arctic Skuas ringed here by Karl-Birger. By coincidence, the next colour-ring on the string read ‘KB’!
Seabirds typically have a slow reproduction but can get pretty old. In fact, the oldest confirmed wild bird is a seabird – a Laysan Albatross of over 60 years called ‘Wisdom’. For Arctic Skuas, the longevity records for European birds lists a 31-year-old Finnish bird as the oldest known individual, with an Icelandic 26-year-old bird as a second. Hence, KB beats the Icelandic bird, and if it manages to survive some more years, maybe it will beat the Finnish as well? We’ll see…
Logger retrieved of a tough phalarope male
When Slettnes finally experienced a day with calm weather last week, Hans and I went out ‘phalaroping’: catching Red-necked Phalaropes using a mistnet. We captured several birds, and were surprised to even capture a male carrying a geolocator! To our surprise, this bird already carried a geolocator during 2015-2016, and got a new one in 2016 that we now retrieved. After three years, it was finally released of its 1.0g logger!
Virtually all geolocators of Red-necked Phalaropes were retrieved one year after deployment, with a few after two or even three years. Two or more years of data from the same individual allows us to study the consistency of individuals in their movements. In Red-necked Phalaropes wintering in the Arabian Sea, this is especially interesting because this area is known for its high variability in where and when food is available. Most Red-necked Phalaropes seem to respond to this variability by moving a lot, except a few – including this bird… The question is: are these movements individual strategies repeated every year, or are they flexible responses to current conditions, changing from year to year?
Unfortunately, after two years the battery of these geolocators is empty, which made it impossible for us (but not for the manufacturer) to download its data. While we wait for this, please have a look at this video (in Dutch) in which we take off the logger and show the track of this individual from 2015-2016.