|A full clutch of Common Ringed Plover eggs with the lighthouse Långe Jan in the background.|
For the fifth year in a row the Common Ringed Plovers breeding in Ottenby, on the island of Öland, have been visited to retrieve and deploy geolocators. The aim for this study is to track the annual cycle of this population and compare to other populations breeding and wintering in different climate regimes. This gives the possibility to see where they spend the winter and stop overs during migration, as well as annual timing of the annual cycle. New for this year’s field season is the deployment of activity loggers. These will indicate when the birds fly or rest, and thus give higher resolution data of how many and how long in time the flights during migration are.
The first individuals in Ottenby where observed in late February. Since they are colour marked they are easy to spot in the field and several observations where reported to me by local bird watchers. A couple of days later I went there to count how many of the arrived individuals had returned from previous years. At this point there were still snow on the ground and the temperature was bellow zero. Nevertheless, about 25 plovers where present and about 15 of these where colour marked. Additionally, I was very happy to see that several of these were carrying geolocators, as well as two of four individuals that where equipped with activity loggers as a test last year. Now the long waiting started. Waders are, during breeding season, easiest to catch while incubating their eggs, which do not start until mid April in Ottenby.
|The field site in beginning of April.|
In mid April I returned to look for the first nest. However, the temperature was still low and most birds where still courtshiping and digging out nest scrapes, which is done by leaning their chest against the ground and move forward by pushing of with their legs. A procedure that make one think about penguins sliding on their belly across the ice. No luck this time. The following week however, the first nests were found and it did not take long to catch the first birds, but none of the individuals with loggers from previous years. Which of course are the gems in this case.
Ringed Plover ringed, sampled, logged and finally photo documented in Ottenby
Bird Observatory’s photo lab. Photo: Ottenby Bird Observatory |
|The loggers are attached with leg-loop harnesses so that the logger itself sits like a little backpack. Photo: Ottenby Bird Observatory|
In mid May the breeding season should have progressed into the later stages of incubation and the field site should be filled with incubating waders. But the temperatures were still low. When I walked out of the car in on May 11 I expected to feel the spring. Instead a cool wind pierced through and the thermometer said 5°C. This was true for many other places as well. There were still some new nest found and the first geolocator were retrieved on the May 12. The day after that the first activity logger was caught back, which was over all expectations since only four of these had been deployed in 2016.
|The first activity logger to be retrieved from a small shorebird.|
It was not until the week after the site got littered with nests. Not only by Common Ringed Plovers, but Redshanks, Oystercatchers, Arctic- and Little Terns too. There were also a lot of migrants, like Red Knots and Dunlins, stopping over on their way to the Arctic tundra. Also, some days the sky was filled with Brent geese migrating towards north-east. One of the biggest highlights however, was to see two pairs of Ruddy Turnstones patrolling and displaying on the meadows. Likely they will breed, something that does not occur every year in Ottenby. It is truly a privilege to see all these birds while carrying out work. In the end 7 loggers were brought back to Lund and two of these were activity loggers. These will shed new light on flight performance in waders, since these are, to our knowledge, the first time this kind of measurement have been retrieved in this group of birds.
|A bownet is being set up over a plover nest. Photo: Marcus Danielsson|
Now I am setting of to follow the spring to more northerly latitudes, namely Abisko, to give the plovers there a visit.