Today we had a foreign surprise up in Björkfjället… Johannes has been studying Dunlins around Ammarnäs since 2008. Since last year, we have been collaborating in a circumpolar project on nest predation/survival rates in sandpiper species, focussing on Dunlin. This year, this was extended with another circumpolar collaboration, which aims to map the migration route of all subspecies of Dunlin (there are quite a few, depending on your taxonomic taste).
This morning we went up to Björkfjället to deploy geolocators on three Dunlins. After I retrieved the third bird from the trap, I noticed it had a metal ring! In previous years, Johannes colour-ringed a number of adults, and metal-ringed many chicks in the preceding years. Hence, my first and only thought was ‘this must be a bird ringed as a chick by Johannes’. Little did I know… I handed the bird to Christian, who had a proper look at the ring. ‘PARIS’ it read!! Hence, this bird got his ring somewhere in France.
Dunlins colour-ringed at Ammarnäs have been resighted in, e.g., The Netherlands and Portugal, showing a south-western migration direction. In this respect, the connection with France is not very surprising. However, which stopovers individuals use for what period is not revealed by these colour-ring resightings, but will hopefully be uncovered next year… if we manage to recapture them!
Yesterday, we had great success with Red-necked Phalaropes. We recaptured two males that received a geolocator last year by Michiel, Piet and Tim. Both birds had a full year of data, showing nice tracks down to the Arabian Sea.
Finally some news from Ammarnäs. Up until today, we had quite a ‘slow’ season. Lemming abundance has plummeted in late-winter, and thus virtually all Long-tailed Skuas are skipping this breeding season (except some weirdos far south at Kraipe and Aigert). We observed some small or medium-sized flocks of skuas that will probably make it back to sea in the coming two weeks.
Hence, our main target has been to (re)capture Red-necked Phalaropes in phalarope-city, Gelmetje. However, this didn’t went smoothly in the last week; we did find some nests, but couldn’t find any birds carrying geolocators. Nor did we find the usual ‘female-flock’ at lake Gelmetje. Deploying all available loggers therefore seemed difficult. This all changed today. While some males have been incubating for about 10 days, we now encountered a decent number of females and found a new nest of a male with logger, containing very freshly laid eggs! We didn’t manage to catch this male (yet!), but we did recapture a female with a logger it got last year by Tim, Michiel and Piet. Great!
The big surprise came only when we returned to the research station: it is one of the two females of which we already had a track! Thereby, the two years of data from this individual sheds some first light on one of the questions brought up by the paper in Journal of Avian Biology on phalarope migration. In this paper, we show that Red-necked Phalaropes usually use several areas within and adjacent to the Arabian Sea, instead of staying at a single site during the entire winter. For example, an individual may arrive in the Gulf of Oman, stay there for some time, then fly south to the spend some time along the southern Omani coast, and subsequently travel to the Gulf of Aden. These movements are presumably in response to monsoon-driven changes in where and when food is available, and the question is to what extent these movements are similar between years. Are they direct responses to local circumstances, changing from year to year, or routes learned during early life, and repeated in subsequent years? This female stayed at three distinct sites during the 2014-15 winter, but spent the entire winter in the Gulf of Aden during 2015-16, thereby showing that individuals can change itineraries between winters.
After five days in the field we are more and more puzzled about this season. We had the first Arctic skua chick yesterday, which is extremely early, and many more nests are about to hatch. These birds must have started laying eggs mid May! Also the Fieldfare chicks nesting near the lighthouse are about to fledge and the vegetation is two weeks ahead. At the same time many skua territories of last years are not occupied and in many territories birds are just hanging around. We also still find nests that were just started. The Red Fox is present again and indeed we found two nests predated already.
Up to now we recaptured 7 Arctic Skuas and their loggers show the wide variety we are used from them: wintering in south America, South Africa and the Caribbean. The 4 out of 7 that we recaptured last year as well, took remarkably similar routes.
Today was rainy with 6/7 Beaufort, not really weather to catch skuas. Besides we had some troubles with our catching device, the snare. It is quite ingeniously constructed around a remotely controlled vacuum cleaner spring, but now it needed some special technical attention (and a new set of batteries as it turned out later). Nevertheless we went outside to check territories at the outskirts of the area and look for Red-necked Phalarope nests. Tomorrow is going to be sunny and the day after even 15 degrees! Time for a dive in the Barents Sea!
In only a few days, a new field season will kick off. This year, we will work at three sites, covered by 9 people.
Obviously, we’ll be working in the most beautiful mountain tundra in the world: Ammarnäs. For me, this will be my 10th year here. Christian Brinkman, Michiel Elderenbosch and Bram Ubels will join me. Both Christian and Michiel have been to Ammarnäs before, in 2011 and 2015, respectively, but Bram is a first-timer. Regardless, we are all very excited to see what this year will bring. After the high lemming peak in 2015, a lemming-low is expected this year, with consequently no or few breeding Long-tailed Skuas. Therefore, the main focus will be on (re)capturing Red-necked Phalaropes. In addition, we will participate in international collaborations, one focussing on sandpiper nest survival in relation to predation and lemming cycles (led by Olivier Gilg, Univ. de Bourgogne) and another on mapping the migrations of all Dunlin populations around the world (led by Richard Lanctot, U.S. Fish and Wildlife Service). Thus, even if the skuas skip breeding, there will be a lot to do!
Others will be going to Slettnes, Norway, for the third consecutive year: Ingrid Tulp and Maria van Leeuwe in the first period, followed by Hans Schekkerman and Morrison Pot. Maria will visit the place for the first time. After a very successful season last year, chances of retrieving geolocators from Arctic Skuas are even better this year. Last years’ data shows extremely interesting patterns, with huge differences between individuals. They are using the entire Atlantic Ocean, plus adjacent waters such as the Mediterranean. More about that later. Another aim at Slettnes is to recapture Red-necked Phalaropes and deploy new geolocators.
Last but not least, Jasper Koster will be positioned at Erkuta, which is located at the Yamal peninsula, Russia. Here, Olivier Gilg deployed eight geolocators on Red-necked Phalaropes, and Jasper will try to retrap these birds. He has been very successful in Tobseda last year, with 140 captures – including two recaptures of birds carrying geolocators. Hope he will reach similar heights at Erkuta!
Last 4th of May, Kim Fischer notified us of the presence of a colour-ringed Golden Plover in Fanoe beach, Denmark. And it is indeed one of our Ammarnäs birds from the project on the ecology of breeding waders in northen Sweden!
The bird was first caught and colour-ringed as a 3+ male in Raurejaure area on 28/06/2011 on its nest, when it was placed a geologger on its leg (attached to a c-ring) to get data on its movements during the non-breeding season. Two years later (2013) it was retrapped again on its nest on 27/06/2013 when the logger was retreived and got two years of data.
Interestingly this bird is the principal character of our lattest article published in the Journal of Avian Biology in 2015 with two years of geolocator data.
In the figure below, this bird is referred to as 1a (for movements in 2011-2012) and 1b (for movements in 2012-2013). Interestingly, in both years the bird used the same stopover area in Denmark, where actually three other tracked birds made one stopover. Therefore this stopover site must be a very important area during both the south and northbound migration.
As you all may remember, in 2011 we placed geolocators on golden plovers in our study area located in Ammarnäs and retreived few of them in the subsequent seasons. Now we have published the data of their whereabouts with interesting results.
Although it was already known about the cold spell-induced winter movements on golden plovers, our study provides some first individual tracking data on this type of movements. In three cases the plovers spent the winter in NW Europe and in four cases they departed during winter from NW Europe to spend the rest of the winter in Iberia or Morocco (one bird that was tracked during two subsequent migration cycles moved to Iberia in the first winter but remained in NW Europe during the second winter).
The four winter departures were associated with a cold spell in NW Europe during which maximum temperatures dropped to freezing. Cold spell-induced winter movements were notably long and fast. The birds that remained at their NW European wintering site did not experience such cold spell. However, the plovers did not always move in response to freezing temperatures, as demonstrated by the individual that was tracked for a second season, when it experienced four cold spells at its wintering site in NW France without leaving. Little information was obtained about spring migration, but one bird had a prominent counter-clockwise loop migration pattern through E Europe. Due to their cold spell winter movements, golden plovers exhibit great flexibility in migration patterns, resulting in a notably large spread in final wintering areas.
Last week, the final version of a new paper on Red-necked Phalarope migration appeared online. It is titled ‘First geolocator tracks of Swedish red-necked phalaropes reveal the Scandinavian-Arabian Sea connection’. Read it at the Journal of Avian Biology website, or drop me a line and I’ll send it to you.
Using the first four geolocators that we retrieved in Ammarnäs in 2014, we were able to confirm that these birds migrate all the way down to the Arabian Sea. This south-eastern direction is rather rare amongst European breeding birds. They covered the 6000-7000km in two to four migration leaps, of which the stretch between the Baltic and the Caspian Sea region (approximately 2500km) was covered in a non-stop flight. The autumn stopover in the Caspian Sea region was remarkably long (up to a month), which is more than what would be needed for refuelling to cover the next migration leap, to the Gulf of Oman. Why they stop for such a long time is unclear. Once they arrived in the Arabian Sea, they showed marked mobility, covering the entire wintering area between the southern Red Sea and offshore Pakistan. In the Arabian Sea, monsoon winds drive huge upwelling systems with marked variation in space and time. Possibly, the phalaropes tracked these variations in productivity, trying to be at the richest feeding grounds at the right time. Although the Arabian Sea is one of the most productive areas in the worlds’ ocean, our phalarope tracks represent (as far as we know) the first seabird tracks in this area.
Thanks to all who have helped, in particular Vincent Hin and Tim van der Meer (who helped me in the field in 2013 and 2014, respectively) and Martin Green and Ake Lindström (Lund University)!