2018-06-18

Common Ringed Plovers: meeting an old friend!



Little ringed plover trapped in Vomb. 
This year's field season in the south (Skåne and Öland) has come to an end. As usual the target has been to catch breeding common ringed plovers to retrieve and deploy various data loggers on Öland. This year’s field season has also concerned retrieval of activity loggers from little ringed plovers around Lund. More about the aim of these specific project can be read about in a previous blogpost from 2017!

It was with great excitement I visited Ottenby the first time in mid-March to see if any plovers had returned yet. Usually the plovers are early and around March 10 many can be seen along the lighthouse road. However, spring had to wait for a while. The meadows were still covered by snow and ice, and only a handful of early arrivals were fighting the cold winds. 

Snow and ice along the light house road.
Then things moved forward swiftly and at last the birds spread out over the area. Males were displaying over their territories in the characteristic “butterfly” flights and the breeding season proceeded as usual. Only a couple of days of harsh weather covered the ground with snow again. But this did not hinder the duties of the plovers. The first nests were found in middle of April and from that point it was time for catching. Several individuals with activity loggers had returned. These loggers were deployed last year instead of the regular light level geolocators.

However, common ringed plovers are long lived and even if “regular” light level geolocators are not deployed anymore, old ones may return. In order to recognize the plovers in the field, each caught bird are individually marked with color rings for easy identification in the field. One female was immediately identified as one that was breeding and equipped with a geolocator in the area in 2013. Remarkably the logger was still on her! Five years have passed! Five years back and forth from the breeding and wintering ground. Unfortunately, the battery in such device do not last for that long, but at least two autumn migration and one spring migration should have been recorded. 

A true hero: this female was logged in 2013 and only this year I was able to catch her.
Soon after the catching at Ottenby was initiated there were time for the little ringed plovers around Lund to start with their breeding choirs. Soon after the first observations we started to search for active nests, which is not easy to find. Last year 22 activity loggers were deployed. The field season was a big success! Seven activity loggers were retrieved, among them one from 2016. 

Well camouflaged little ringed plover nest

This was the end of chapter one of this year’s field season. Now waits a second spring in the north. First stop will be Kalix and a small island in the Happaranda archipelago, Malören, and second will be Abisko.

/Linus Hedh

2017-08-29

Expedition to the High Arctic desert – Henrik Krøyer Holme July 2017

In late June a party of three: Morten Frederiksen (Aarhus University, DK), Arne Andersson (CAnMove) and Jannie Fries Linnebjerg (Former CAnMove, now Aarhus University) went to the High Arctic desert to participate in a project initiated by Aarhus University. The aim was to investigate the foraging areas of the two Arctic seabird species: Ivory gull (Pagophila eburnea) and Sabine’s gull (Xema sabini).

These two species only breed in the Arctic, so in order to find them, we had to postpone the Scandinavian summer-life and move to a small caravan in Northeast Greenland for three weeks in July. Ivory gulls and Sabine’s gulls breed in small colonies and are known to breed on the islands of Henrik Krøyer Holme, approx. 15 km off the mainland of Northeast Greenland. The area is extremely remote, which means logistic challenges, such as chartered flights from Svalbard to the Danish airbase Station Nord, and airlift with a small Twin Otter aircraft to the study site.
The team is ready for take-off from Station Nord to Henrik Krøyer Holme.
 
The orange caravan (the camp site), kindly lent to us by the Danish Meteorological Institute.
Henrik Krøyer Holme is located close to the North East Water polynya, or area of recurring open water in the pack ice. However, in some years the islands remain linked to the mainland by fast ice far into the summer, and this was the case in 2017. This meant that terrestrial predators such as Arctic foxes (Alopex lagopus) had access to the islands. Many birds choose not to risk breeding under these conditions, and instead wait for a better year.

This was the case for the ivory gulls, which did not breed at all on the islands this year, but fortunately, (at least for us!) the Sabine’s gulls struggled on with their breeding. This gave us the opportunity to deploy GPS loggers on eight breeding birds, and we could follow their whereabouts by remotely downloading positions from the loggers.


Several days were spent wandering about the island, trying to locate the breeding birds.
The main island is about 10 km2, so there was quite a lot of ground to cover.

Catching the birds turned out to be more difficult than expected, so a lot of time and energy went into
modifying traps and trying all sorts of different catching methods.



A Sabine’s gull equipped with a GPS data logger on a leg-loop harness.
Along with the work, there was of course also time to enjoy the harsh but exotic polar landscape and wildlife, like spotting walruses (Odobenus rosmarus) and narwhals (Monodon monoceros) close to the ice edge. And the Arctic fox, although making life difficult for birds and scientists, is very cute!
Arctic fox with an Eider egg.

Armed to the teeth. We never saw a polar bear, but did have one visiting our
camp when we were out in the field.

Polar bears are normally very curious and cautious when encountering new things.
Polar bears do not like raw oats…
Nor toilet bins…
And our rubbish was not that interesting to the polar bear either…luckily.

The photographer is busy shooting eiders and does not see the polar bear in the background...

The landscape at Henrik Krøyer Holme is proper Arctic desert, with very little vegetation.
Only six species of flowering plants have been registered on Henrik Krøyer Holme.
One of them is the Arctic poppy (Papaver radicatum
).
Arne trying to get a close-up picture of an angry Arctic tern.

The rough terrain was hard on our boots. After four days, Mortens sole had pretty
much come off the boot and he had to screw it back on.



 
Three interesting and nice weeks had come to an end. And I think we were all slightly relieved when the plane finally arrived :)

Arne & Jannie

2017-08-24

A summary of the summer with nightjars (2:2)


 
The nightjar´s plumage lets the bird blend in in the habitat
Last week marked the end of a quiet successful field season with the nightjars in Småland, SE Sweden. We mainly experienced relatively calm, dry, and warm summer weather which boosted the activity of the nightjars as well as provided good trapping conditions throughout the season. As a result, we managed to retrieve eight activity loggers to add to the one mentioned in an earlier blog post.
We did also retrieve five GPS-tags containing migration data with high spatial resolution. We have in an earlier study based on light logger-derived data gained knowledge about the large-scale temporal and spatial migration pattern of our birds. The GPS-tags will allow us to go one step further and look into the birds´ decision making regarding e.g. departure decision, route choice and wind selectivity along the entire migration route.
As the nightjars are about to set out for the journey to their nonbreeding ranges we will stay behind and begin the exiting work analysing the retrieved data.


A nightjar demonstrating its huge gape

/Gabriel

2017-07-09

Common Ringed Plovers from south to north (2:2)


The field station with the lake Latnjajaure in the background, still covered with ice and snow.
Loading up a helicopter with three weeks worth of supply and field equipment is always exiting. Loading one that it’s heading to a place where data loggers sitting on Common Ringed Plovers is even more exiting. Except for my self three other people were preparing for getting up to Latnjajaure (jaure means lake in Sami) in Abisko, working with everything from plant phenology to gas emissions in post-permafrost sites. With the mountains in our bearing we took off from the helipad in Abisko on the 14th of June.

A newly ringed Common Ringed Plover with an activity logger visible on the back.

The reason for my stay was to catch Common Ringed Plovers. As mentioned above to retrieve geolocators, but also deploy new ones. In an earlier blog post from June 13th I mentioned that this year I use activity loggers. This gives the opportunity to in better detail describe a number of aspects of flight performance in the Common Ringed Plover, such as duration of individual flight bouts and the number of flights and consecutive stop-overs. The overall aim is to compare these aspects between populations migrating different distances and breeding/wintering in different climate zones. The population this field trip is aimed for breeds close to one of the Abisko Scientific Research Stations/Swedish Polar Research Secretariat’s field station in Latnjavaggi (vaggí means valley) approximately 15 km west of Abisko. 

A Common Ringed Plover nest beautifully placed among flowering Alpine Azela (krypljung) and Dwarf Willow (dvärgvide).
Despite the present warm weather down in Abisko there was as usually much snow left up around the lake. This year was particularly late and much of the previous breeding sites were covered with snow. During the first days I was somewhat worried that the plovers had given up the site already in the beginning of June, when they usually arrive. The only two individuals observed during the first two days were one unmarked (new) and an old friend who has had a territory close to the field station for the three subsequent years. However, this season he ended up alone.  Slowly however, more individuals showed up. One male I was very exited to see again. Also he has kept his territory since the beginning of the project in 2014. What makes him extra special is that he used the same exact nest scrape for three years in a row. This year there was a new scrape, but located only ten meters from the previous one.

Measuring the wing area, one of the many measurements taken.
The first bird was caught short after incubation had started. Following that most birds in the valley where caught except for the lonely male. Right after midsummer several waders were seen on the lakeshore. Among them the first Ruffs ever observed in Latnjajaure, a small flock of Common Ringed Plover and the first Dotterel for the season. This individual came flying on high altitude through the valley. That behaviour together with the flocking behaviour of the plovers made me draw the conclusion that these were failed breeders moving towards initial staging areas.

Not long before the first helicopter back to Abisko was going I stumbled upon a new nest. It turned out that both the male and the female was ringed and logger at a previous year. The female carried a logger that were deployed in 2015, which means that it could potentially contain data from two consecutive years! Due to these and a couple of days of bad weather, which did not give any opportunity for trapping, I missed the helicopter. 
 
Bad weather in the summer could mean snow in the mountains.
After a couple of trapping attempts a few days later I managed to retrieve both loggers. After making sure, to the best of my ability, that there was no more breeding pairs I hiked back to Abisko with a total of four geolocators to be analysed when coming back to Lund.

The fantastic bird life in the area is not the only thing that amazes. This is a Diapensia lapponica, a resistant pincushon plant that each year survives thick snow cover, freezing and thawing during the flowering period, and trample by reindeers. This particular clone is a real champion since it is, judged by the size, about 800 years old. Maybe it started its life during Marco Polo adventures in eastern Asia?

 Amazing morning at Torneträsk, in Abisko, after coming down from Latnjajaure.


/Linus Hedh
2017-07-06

2017-06-29

Visiting the Caspian Terns of Ostrobothnia

The end of May is high time for incubation amongst the Caspian Terns of the Baltic. So with this knowledge in hand I headed for Ostrobothnia, to the Kristinestad archipelago to meet up with the resident tern expert and collaborator, Patrik Byholm. This archipelago has a markedly high density of breeding Caspian terns with a colony of about 70 breeding pairs and some 25 solitary breeding pairs in the area.
The Kristinestad archipelago boasts a nice diversity of the classic Baltic seabirds such as Common Eiders, Ruddy Turnstones, and White-tailed Eagles as well as healthy contingency of the ever-charismatic Little Gull
The goal of the trip was to catch adult terns for the attachment of GPS-GSM loggers for revealing migration and habitat use movements. To begin the season we had 4 birds with working tags returning and setting up their breeding attempts, each on their respective islands. So our task was to catch the un-tagged partners of these tagged individuals to be able to then later tag the young as well to hopefully get the successful migratory movements of an entire family group. Exciting stuff, but first things first we had to catch the un-tagged partners. To our good fortune a newly formed pair of terns just so happened to be two birds that were already tagged! Two-birds-one-stone kind of luck!

Ingströmsberget; a rather typical breeding island for a solitary pair of Caspian Terns. Other inhabitants include Great Black-backed Gulls, and Barnacle Geese.
The first day out was an unequivocal success, with both the un-marked adults being captured and tagged. This was a relief as capturing the right individual on the first attempt greatly reduces the stress for all parties involved.

Patrik releases our first individual Caspian Tern of the season, complete with a new GSM backpack.
Not all days are made for sea-faring! This is especially true when the work involves landing on exposed islands in high winds. So our off days were spent in the forest checking a collection of pygmy-owl boxes that Patrik had set up back when he was still in high school. This provided a wonderful opportunity to take full advantage of my time and build a broad perspective the bird life of the region, from the eider of the outermost islands, to the red-breasted flycatcher of the innermost forest patches. A welcomed contrast!
A partial clutch of few day old pygmy owl nestlings. The large feathers are leftovers from avian prey brought back to the nest by the male. These end up becoming insulating nest-lining!)

When the sun returned, as did we to the sea. We continued surveying islands for possible Caspian Tern breeding activity and also set up a remote camera on the colony island of Gubbstenen. These cameras allow for remote re-sighting of ringed adults breeding on the colony, as well as identification of predation events by eagles, ravens and the like.

The remote camera gets settled in amongst the breeding terns of the Gubbstenen colony.
In the last few days of my time in the archipelago we had 2 loggers left to deploy so we decided to try and capture a new pair. We identified an apparently solitary breeding pair on an island that seemed to lend itself to expedient trapping. So we gave it a shot. The first day went without a hitch, with the target bird captured and the tag deployed. Thereafter the pair was given a days rest so as to avoid disturbing their incubation too much. Upon our subsequent return to the island we realized that the pair was in fact not alone on the island but that two other pairs had set up shop and laid eggs! It had become a veritable mini-colony. With the title of ‘solitary pair’ defenestrated, we decided the information would be of no less value and went ahead and captured the remaining partner of the original pair.
A GPS-GSM logger that will communicate with the cellular network to provide information on the birds whereabouts is looped around bird’s legs and loose ends are sewed up for secure fitting.

With all GPS-units deployed and many amazing birds and environments observed I hopped on the ferry back to Sweden, where other tern-inhabited archipelagos beckoned!

Baltic glory


- Martin Beal

2017-06-26

A flying start on the nightjar field season may help us learn how much nightjars fly (1:2)


You know the frustrating feeling when you have a dense swarm of gnats around your head, biting wherever they find an opening when you lower your guard for just a moment. That is in fact a positive feeling if you are about to catch some nightjars because a lot of gnats usually means that the nightjars will be active and hence a lot easier to catch. So, it was with rather high hopes we set out into the warm early summer night for our first trapping effort for the season at my field site. 

Urban Rundström with whom I trap nightjars has been spending (almost) every available summer night catching and ringing nightjars in eastern Småland since 2010 and just the other day he manage to ring nightjar number 600 in his project, which is pretty amazing when comparing to the approximately 1200 nightjars ringed in Sweden during the first century of bird ringing! For the tracking project we have focused on an about 50 km2 square of forest squeezed in between relatively large areas of agricultural land, the river Emån and the Baltic Sea. The area is rich in nightjars and it is heavily managed which enable relatively easy access to most territory-holding birds with a regular car. 

The night turned out to very successful, just as the gnats had indicated, and in the first morning light we could note that our efforts had resulted in 11 trapped birds! One of those was an old acquaintance that we met for the first time back in 2013. Then he was a young male born the year before. We have caught him every year since, more or less in the same spot. This year he had carried a miniature data logger that regularly is sampling and logging his flight activity throughout the annual cycle. With his contribution we hope to learn more about the daily and annually flight activity in this cryptic long-distant avian migrant.
 /Gabriel

2017-06-13

Common Ringed Plovers from south to north (1:2)



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. 

Female Common 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. 

 //Linus Hedh