After an adventurous summer in the Arctic, I returned to my desk to dig into the heap of data which we collected. In the first place we collected 25 GPS-tracks showing the migration routes of Barnacle Geese, but it gets more exiting when we can link this to what the geese did on the breeding grounds. We followed the nests of these geese in particular, but also weighed the geese on their nests and even samples the feathers of the small goslings right when they emerged from their eggs. By linking all these data, we can get an idea how individual geese with particular migration schedules differ in their performance on the breeding grounds. If you migrate fast as a goose, can you still bring enough body reserves to the breeding grounds to lay enough eggs and incubate them? And where do the resources to produce this egg come from, all the way from the Netherlands or do the geese use local grass to lay their eggs?

To start answering these questions, we first take a look at the migration schedules. As I said, we collected tracks of 25 geese that made their spring migration to Tobseda. These geese differed both in the places where they stopped during migration as well as their timing of migration. I have made 3 categories of geese: The yellow “Baltic” geese made a stopover in the Baltic region (South-East Sweden, South-West Finland, Estonia), the blue “Arctic” geese made a stopover in the Russian Arctic (White Sea, Kanin peninsula) before the breeding grounds, while the red “Direct” geese flew to the breeding grounds hardly without stopping in between, some in only 4 days! (The green “Early” goose is the exception, leaving very early and stopping often)

So Barnacle geese differ in their migration schedules, but what consequences does this have? One important factor regulating the reproductive success of geese nesting in the Arctic is the moment in the year they initiate nesting. As the season is very short, the geese that start nesting early are often the most successful. Their chicks not only have a longer time to feed before they have to head back to their wintering area in the Netherlands, they also meet the best quality of grass that grows early in the season. So any geese would like to start nesting early, but in order to do so they need to have enough body reserves to lay their eggs and incubate them for about a month. Do birds that differ in migration strategies also differ in the date of nest initiation and body weight on arrival?

In the graph you can see all the geese from which we could download their spring migration track and also find their nest. From the spring migration track we extracted the migration time (from winter area to breeding colony) in hours, and plotted this against the moment this particular goose started its nest (the units might confuse you, as we plotted initiation day in days since April 1st). While the geese with direct and baltic migration strategies all start their nest all roughly around “April 65th” (which is equal to June 4th), the geese which use an Arctic stopover all start around 4 days later. This might not sound like a lot, but these 4 days might just make the difference to migrate back with 4 healthy chicks, or no chicks at all. Some geese we also weighed on the nest, and their body weight is indicated by the size of the dots. You can see that especially geese that use an Arctic stopover are extremely light, and probably less able to cope with a long incubation period.

Some geese are not only able to directly migrate to their Russian breeding grounds, they also initiate their nests early and arrive with enough body weight! That these geese are able to pull this off is surprising and very new, but also raises a new question: how can they do it? Luckily we can really closely follow these geese with the new technology, as the GPS-loggers which we have equipped our birds with not only record GPS positions, but also the acceleration of the bird. A so-called ‘accelerometer’ can be find in many modern devices such as your phone, and measures your speed of acceleration and movement. It is for example used in your training app to measure the steps you take, or even simpler, to measure whether your screen is tilted so it should adjust to ‘landscape’ or ‘portrait’ mode. Using the accelerometer in the GPS-loggers, we can see what behaviour (such as flying, walking, resting or grazing) the goose is displaying at the moment of measurement. In this way, we know exactly how many hours the geese forage per day and where.

Here we plotted again the number of hours spend on migration but now on the y-axis, and the geese that use a direct migration are found in the lower bottom of the graph (less than 200 hours). We plotted this against the fraction of time spend foraging in the Netherlands, and in particular in agricultural areas. Prior to migration, barnacle geese traditionally used saltmarsh areas to graze, but over the past decades they have switched more and more to agricultural areas. We can see that the geese that are able to use a direct migration strategy mostly forage on agricultural areas. The grass there might be richer in energy, and could be the way to fuel up faster and take a direct migration route. The intensification of agriculture might thus have enabled geese to use direct and maybe more efficient migration schedules, allowing them to better cope with climate warming in the Arctic.

Three weeks ago we returned from the Russian Arctic, back into late summer Netherlands. The geese will stay a little bit longer, and will probably start flying back to the south this week. Our time in Tobseda was great, and we were able to collect some great results for our research.

 

When we arrived the 28th of May, there was very little snow, much less than usual. Most of the Barnacle Geese had arrived before us, and were settling into the colony. We could not locate any Barnacle Goose with a GPS-logger yet, but set out our relays in order to track them. Hunters looking to shoot overflying geese were dissapointed, since migration was largely over. They still shot quite a few of the Barnacle Geese in the colony, and this is when we saw the first ‘logger-bird’ – Shura, the bird that we downloaded on Schiermonnikoog this Spring, had been shot on arrival. A real shame. Luckily it did not take long before other loggerbirds started showing up in the colony, and eventually we recorded the presence of 30 loggerbirds (of the 40 we tagged last year). Of some birds we lost track, but in total we could download data from 24 birds. 18 of these started nesting in the colony.

From the GPS tracks of these birds, it became clear that they seem to migrate using three different strategies. Some geese leave the Netherlands in the end of April / early May and stay in the Baltic region to gain fat reserves. This is know as the classic strategy, and it is assumed that most Russian Barnacle Geese used this strategy in the past. Other geese left the Netherlands later, around mid-May, but all geese crossed the landmass between the Baltic Sea and the White Sea at the same moment, around the 19th of May. Although we expected geese to use Arctic stopover sites to fatten up before arrival in Tobseda, most geese continued flying and finished the complete journey between the Netherlands and the breeding grounds in 5 days. Only some geese used Arctic stopover sites around the White Sea and Kanin peninsula.

 

We monitored nests in the whole colony and kept track on the number of eggs and the initiation of nesting for all 650 nests. We payed special attention on the nests of loggerbirds: One of the first striking things is that all geese using Arctic stopovers arrived late and bred later than the geese using other migration strategies. Next to normal monitoring we weighed each loggerbird al multiple moments using a platform scale which we put under the nest. This way, we can relate the migration data to data of nesting success, and calculate a weight on the initiation of nesting. Also we collected the shit that we found around the nest every week, so we could estimate the amount of food a female takes in during this period of time.

 

We aimed to visit the nest at the moment of hatching, in order to see how many eggs actually hatched, and to tag the chicks. Using a metal mark, we could recognize them later in the season and provide them with colour bands. In July we spend a long time in hides to observe the geese and count the number of chicks in each family, so we could make estimations on their survival. Also we wanted to know how the geese divide their time. In order to get to know this, we had to do 24 hour observations on the geese – long periods of time in the hide, quite a challenge! As soon as the adults started moulting their wing feathers, we could start catching the geese.

 

Our aim during the moult catch was to 1) recapture individuals which we equipped with geolocators, loggers which can only be read out after recapture, and 2) to catch chicks which were marked on the nest, so we could measure growh. During moult the geese cannot fly, and they tend to escape to the water in large flocks. We set up a funnel-shaped net, and used boats to drive the geese into our net. We were able to catch big groups of non-breeders (without chicks), and many smaller flocks of breeders with their young. In total, we could recapture 28 birds with a geolocator! Also we were able to recapture many of the chicks which we gave a webtag. In total we caught 4600 geese, of which we gave about 350 a colour ring combination.

 

Now it the time to analyse the data and further look into the question – can these geese deal with Arctic Amplification? Meanwhile, Stefan has recorded our activities in Tobseda on film, and has prepared an item which will be show on Dutch television! You can watch on September 23th, NPO 2 at 19:20. Here you can watch this item and other movies Stefan made during the summer.

Hoewel het een tijd heeft geduurd, begint het in Nederland op te warmen en nadert het einde van onze lente. Een koude lente, waarin veel trekvogels laat in Nederland aankwamen en lokale broedvogels relatief laat zijn begonnen met broeden. Voor de ganzen lijkt zo’n koude lente prima, ze hebben immers een dik verenpak en zijn gewend om de zomer door te brengen in de poolgebieden, waar het flink wat kouder is. Maar terwijl het voorjaar in Nederland laat op gang is gekomen, lijken de zaken er in het noorden anders voor te staan. De sneeuw is op veel plaatsen in de Arctis al vroeg gesmolten en het ijs in spoed zich al een weg naar de zee. Dit betekent dat het gras, het belangrijkste voedsel voor de ganzen, al snel de grond uit komt zetten, en de ganzen wellicht te laat aankomen om hun voordeel te doen van een voedselpiek aan het begin van de groeiperiode. Volgens klimaatmodellen warmt het noordpoolgebied sneller op dan onze gematigde streken, en zal deze situatie zich in de toekomst alleen maar vaker voordoen. De vraag is of ganzen als lange afstandstrekkers zich goed kunnen aanpassen aan deze veranderingen.

Afgelopen voorjaar hebben we, net als in 2014, een experiment gedaan op verschillende locaties langs de trekroute van de Brandgans, waarbij we kijken naar het effect van klimaats opwarming op de belangrijkste voedselplanten van de Brandgans. Voorlopige resultaten laten zien dat het effect van opwarming groter is in de Arctische broedgebieden dan in de gematigde wintergebieden en pleisterplaatsen. Dit voorjaar hebben we met hulp van studenten het experiment voortgezet op Schiermonnikoog en Gotland, Zweden. Ook zullen we het experiment wederom opzetten aankomende zomer in Rusland. Omdat het een veel kouder voorjaar was dan in 2014, zijn we erg benieuwd naar de resultaten van dit jaar! Kijk hier voor meer informatie over dit experiment.

 

 

Brandganzen broeden niet alleen in het Arctisch gebied, maar sinds de jaren ’80 ook in de gematigde streken – het Baltisch gebied en ook Nederland. Broedende brandganzen zijn in Nederland geconcentreerd in de delta – Zuid-Holland en Zeeland. Deze ganzen zitten jaarrond in Nederland en zijn dus eigenlijk geen trekvogels meer. Maar hoeveel verschillen ze nu van hun migrerende soortgenoten? Uit eerder onderzoek weten we dat deze ganzen relatief te laat broeden ten opzichte van de voedselpiek in Nederland, maar dat de overleving van de jongen een stuk hoger is. De meeste juveniele ganzen van de Arctische broedgebieden sneuvelen namelijk tijdens de najaarsmigratie naar het zuiden. Maar hebben de Nederlandse broeders ook echt minder kosten dan hun migrerende soortgenoten? Ze hoeven immers niet 3000 kilometer op en neer te vliegen, maar wellicht is deze trektocht wel minder kostbaar dan we tot nu toe hebben gedacht. En spenderen Nederlandse broeders net zoveel tijd om op te vetten?

Om dit soort vragen te beantwoorden willen we de Nederlandse broedende brandganzen op de voet volgen. Met dit doel hebben we 8 vrouwelijke Brandganzen op de Westplaat Buitengronden, Zuid-Holland, uitgerust met GPS-loggers. Vorig jaar hebben we al 40 Brandganzen in Rusland uitgerust met deze zenders, en we hopen zo mooi de vergelijking te trekken met deze vogels. Tegelijkertijd monitoren we de broedende brandganzen op de Westplaat, en weten we hoeveel eieren deze ganzen leggen, hoeveel daarvan uitkomen en hoeveel kuikens overleven.

 

 

De Brandganzen zijn al grotendeels vertrokken uit Nederland. Wij vliegen ze snel achterna, en vertrekken aanstaande vrijdag 22 Mei naar Noord-Rusland, op expeditie naar de Brandganzen broedkolonie bij het verlaten dorp Tobseda. Sinds 2002 worden er expedities georganiseerd naar deze plek voor Brandganzenonderzoek. Ons doel dit jaar is voornamelijk om data af te lezen van GPS-loggers waarmee we vorig jaar 40 ganzen hebben uitgerust. Deze ganzen zijn inmiddels op en neer gevlogen naar Nederland, waar we al een gedeelte van de data hebben kunnen aflezen (zie vorige blogpost). We zijn voornamelijk geïnteresseerd in de de aankomstdata van deze ganzen in de broedgebieden, of de ganzen lang of kort in Nederland zijn gebleven, en of ze gebruik hebben gemaakt van verschillende pleisterplaatsen langs de trekroute. Zo kunnen we vergelijkingen maken tussen ganzen met een ‘traditionele’ migratiestrategie, waarbij ze in April uit Nederland vertrekken en een tijd verblijven in het gebied rond de Oostzee, en ganzen die pas in Mei uit Nederland vertrekken om in één keer door te vliegen naar het hoge noorden. Ook willen we van deze ganzen weten hoe zwaar ze ongeveer zijn aangekomen in de broedgebieden, hiervoor zullen we de ganzen gaan proberen te wegen terwijl ze op hun nest zitten. Daarnaast zullen we de nesten van de ganzen goed in de gaten houden om bij te houden hoeveel eieren ze leggen, hoeveel kuikens daaruit komen en hoeveel daarvan overleven.

Kortom, wederom een drukke zomer! We zijn bijna klaar om te vertrekken en druk bezig met de laatste voorbereidingen. Daarnaast zullen deze zomer opnames gemaakt worden voor een aflevering van het programma ‘De Kennis van Nu’, uitgezonden door de NTR op Nederlandse televisie. Voordat dit wordt uitgezonden in het najaar, zullen we ook een aantal keer op de radio te horen zijn! Radio- en blog-updates zullen gedurende deze zomer te volgen zijn op de website npowetenschap.nl. Tot in Augustus!

As more and more geese with GPS-loggers are being spotted in the Netherlands, I became more curious to know what data they carried in those GPS backpacks. Many people use satellite tags to track birds, as these will automatically send the data to your computer no matter where the bird is. The tags we use are loggers, an thus only store the data. Downloading the data from these loggers can be done remotely using an antenna connected to a laptop, but you still need to be rather close to the goose (500m). In order to do this, you first need to find the bird before you can download the data.

Because in total 4 of my geese with GPS-loggers had been sighted in south-western Friesland, I decided that this would be the first place to try and download data. Me and Thijs Fijen therefore planned a long weekend around Akkrum. We started driving around in farmlands where many small groups of Barnacle Geese were foraging. It did not take long before our antenna picked up the signal of a logger-goose close to a farm, we soon spotted the goose W1N6 in a small flock. Although we could stay close to the goose for over 2 hours (and were even offered coffee and biscuits from the people in the farm) we were not able to download more than 150 kb of data before the goose flew off. Too bad. We resumed our journey to Vegelingsoord were a huge flock a geese was resting close to a nature area, but did not see or track any goose with a GPS-logger. In the end of the afternoon we returned to Akkrum where a big flock of geese was present. The system soon picked up another GPS logger goose, W1NJ, and we were able to download 500 kb of data before the flock suddenly flew off. The sun was setting, and we returned home, happy to have found 2 geese and to see that the geese seemed to be in good condition. The next day we returned, but were unable to find any logger-geese. Although we were able to download some data during the weekend, this data was only from movements on the breeding grounds, and no data on the migration routes of the geese.

On the island of Schiermonnikoog researchers from the University of Groningen (RUG), Netherlands Institute for Sea Reasearch (NIOZ) and SOVON have for long been doing research on spooonbills and oystercatchers, which have been equipped with similar GPS-loggers as our geese, also from the Universty of Amsterdam. These researchers are also tracking their birds with the same antenna system, and had set up this system in early spring of this year. After setting-up, goose W1NE which had already been seen once on the island around Christmas, was soon picked up by the system and was sending data! After some days we got enough data to get an idea of the movements on the breeding grounds but also the migratory route of this goose. Last week I received the last part of the data, we now have a complete overview what this goose has been doing for the last winter. Apparently it visited Schiermonnikoog only for 2 weeks during Christmas, after it made a winter trip to Groningen and Zeeland, before it came back to Schiermonnikoog in early March.

Also, we have the first picture of a logger-goose in the Netherlands. Peter Matthijsen managed to photograph LAB5 and her partner in the Westplaat Buitengronden.

 

Although the first Brent geese were already seen in the Netherlands in September, it was about two weeks ago that other Arctic geese showed up in the Netherlands. On the 2nd of October big flocks of White-fronted Geese started coming into the Netherlands, and it didn’t take long before the first ringed ones were found: White-fronted geese with white neck-bands including GPS-loggers, banded on Kolguev by Andrea Koelzsch. But no ‘Arctic barnies’ yet..

Last week started out sad: a tagged Tobseda goose, W1N-, named Maria, was shot in Estonia on the 6th of October and reported to the Estonian Ringing Centre. Sad to hear, but a first sign that Russian geese were on their way to the Netherlands. I published a short article on the web on our banded Barnacle Geese to alert potential ringreaders, which was spread by nature lovers. Also, I gave a short presentation on the German goose meeting of the DO-G in Xanten last saturday, which was received by much enthousiasm.

Then last Thursday, the first Tobseda goose OPYN (Orange P, Yellow N) in the Netherlands was found, banded here in 2013 and seen this year on the breeding grounds in Tobseda! Some days later the first White and Black banded birds, W5NC & W5N6, two siblings, were seen in Friesland. The game is on!

So, for all potential ring readers, something on what to look for when you search for Barnacle Goose rings and what to note down. First of all, since it is still early in the season, rings are difficult to read in the high grass and finding banded birds can take quite some effort. The white rings which the Barnacle Geese banded this year have on their left leg, are very well visible, and should grab your attention to look for the band on the right leg. This one is, however, black and can be very difficult to see and read. Take your time, wait untill the bird is close, and you will be rewarded Note that this colour might be remind by some people as dark blue (B.) ring, which has been used in the past, but must be noted down as a black (N.) ring in geese.org.

When finding an adult Barnacle Goose with a W.N. combination, it is important to check whether the bird has any offspring following (see instructions for observations). Earlier in the winter, families of the geese are more often complete since the offspring becomes independent during early spring, and juveniles are easier to distinguish from adults in the period. This means that now is the time to go out looking for those geese. Below I provide some examples how to identify juvenile Barnacle Geese.

The upper picture shows a typical juvenile, while the lower shows an adult Barnacle goose. Note that the juvenile has 1) spots instead of clear defined lines on the flanks, and 2) less black marking on the back and less defined white bars on the wing feathers.

Below we see a picture of juvenile bird in the field, with an adult bird below for comparison (Thanks to Stephen Menzie for the pictures). Can you find the differences as pointed out in the drawings above?

Good luck finding the geese and their chicks in the field!

Just a short update this time, as Barnacle Geese from Arctic Russia are currently getting closer and closer to the Netherlands. On the 15th of September, the first flocks of Barnacle Geese were seen flying south over the city of Naryan-Mar, 150km from the breeding site of Tobseda. Now, on the 23th of September, Barnacle Geese started arriving in great numbers on Gotland, Sweden. They will probably spend some time here foraging, after which they still have 1000km left to fly to the Dutch wintering grounds.

The Barnacle Geese have prepared for the long journey to the south, and are about to start flying towards North-Western Europe. Observers in Germany, Denmark and the Netherlands, pay attention for incoming Barnies, look for white – black colourbands and post your observations on www.geese.org!

It is only late August, but the short Arctic summer is over and autumn is upon us: Vegetation growth is slowing down, mushrooms and berries are appearing, and at night it is actually starting to become dark! It is time to get back to the Netherlands after a successful field season!