The Bijagos Archipelago in Guinea Bissau is the focus of attention of a large scale ecological research project (2018-2022). The project is funded by the MAVA foundation and is a collaboration between Guinean, Portuguese and Dutch research institutions:
Guinea-Bissau: Palmeirinha, Tiniguena and ODZH – Organização para a Defesa e o Desenvolvimento das Zonas Humidas
Portugal : Universidade de Aveiro, Departamento de Biologia-CESAM and Universidade de Lisboa, Faculdade de Ciências-CESAM
The Netherlands: University of Groningen and NIOZ – Royal Netherlands Institute for Sea Research
This blog keeps a photo story of the project, made by Theunis Piersma – starting January 2019.
The first week of field work in 2019, at Urok. The NIOZ/RUG team with El-Hacen teaching the next generation of biologists and, and Jannes Heusinkveld, specialist of field data collection with drones, testing equipment.
The progress workshop of the steering committee of the Mava Foundation project ‘Waders of Bijagos’, was held on 27-28 January 2019, in Casa do Ambiente/IBAP in Bubaque, Bijagos, Guinea-Bissau.
Here an impression of the workshop, with on the right: Mohammed Henriques, joint PhD student of Universidade de Lisboa (Tidal Wings) and the University of Groningen, with Aissa Regalla de Barros (Instituto da Biodiversidade e das Áreas Protegidas – IBAP) and Toze.
Mohammed Henriques, joint PhD student of Universidade de Lisboa (Tidal Wings) and the University of Groningen, with Aissa Regalla de Barros (ODZH) and Toze
Aissa Regalla de Barros (IBAP) introducing the project t-shirt, with Bar-tailed Godwit with NIOZ colour-rings!
José Alves, and Ana Coelho, joint PhD student of Universidade de Aveiro and the University of Groningen summarizing the work of Universidade de Aveiro.
Afonso Rocha, from Universidade de Aveiro, presenting lots of resightings, esp. of Bar-tailed Godwits, that were colour-ringed in N Europe, including The Netherlands!
Teresa Catry of Universidade de Lisboa, one of the researchers behind Tidal Wings.
El-Hacen Mohamed El-Hacen presenting SIBES Bijagos for the second phase of the MAVA Project. The design of de SIBES Bijagos grid is based on the SIBES Wadden Sea project.
Guido Leurs, the shark specialist in the project.
Laura Govers, University of Groningen, summing up the conservation relevance of the project.
The team is taking off for a night of catching:
Here we were dropped off from motocar. Legwork from here on:
Reaching the camp at the edge of the mangrove, and then some mangrove work, to reach the area where we want to set the nets:
Net setting in the mangrove (with Anna Coelho in the middle). Afonso Rocha setting up the decoys. From here it’s waiting for darkness and for a catch:
Processing the catch (!) in the middle of the night:
Datatagging a Grey Plover by Teresa Catry and Jorge Gutiérrez
And the aftermath, with Afonso Rocha:
An important part of the work is collecting data of birds with colour-rings, either ringed during this expedition or elsewhere in the Flyway.
The first weekend of February 2019 Jorge Gutiérrez resighted a male Red Knot with a yellow flag and four colour rings. After some text messaging back-and-forth with Job ten Horn and Jan van Gils from the Royal NIOZ , it turned out that he was captured and ringed at its breeding ground in Taymir, Russia, last summer on 17 July 2018. At that time he was guiding his chicks over the tundra. Obviously when Jorge saw him he had a breeding plumage score of 1 (and not 5 as in this photo).
Project title: Waders of the Bijagos – Securing the ecological integrity of the Bijagos archipelago as a key site for waders along the East Atlantic Flyway
Students: Mohammed Faza Henriques Baldé, Ana Coelho, Guido Leurs
Report of Black-tailed Godwits expedition in Senegal by Jan Kramer and Rennie Kramer-van den Akker. In Dutch
Jan Kramer and Rennie Kramer-van den Akker traveled through Senegal from 27 November to 7 December 2018 to search for Black-tailed Godwits that are colour-marked (near their home) in The Netherlands by teams of the University of Groningen. Jan and Rennie are part of a large community of volunteer observers who contribute to the data collection of the godwit demographic project.
Jan and Rennie traveled with their guide Idrissa Ndiaye and driver Saliou Diop. From Dakar they first went to the Senegal Delta near Palmarin where they spend two days to find godwits. Other promising areas for godwits included in the trip were situated between Joal Fadiouth and Palmarin, such as Fatick, Diofor, Mammangueth, Samba Dia and a wetland near Mbissel. Next they visited National Park Djoudj, the Station Biologique near the Tocc Tocc Reserve, Lac de Guiers and surrounding rice fields. After that they went to the Guembeul Reserve and the wetlands between highway N2 and the Senegal river. Finally, returning to Dakar they made a stopover at small urban nature reserve Technopole. How long will this nature reserve survive the ever-growing city ?
The first day they already saw 25 colour-marked godwits, 20 birds from the RUG project and five from other projects. During the trip they checked 100s of godwits for rings and collected detailed data for a grand total of 60 individually colour-marked Black-tailed Godwits. The life histories of 44 RUG colour-marked godwits were collected.
Some impressions of the hotspots and the field work of Jan and Rennie, and their guide Idrissa (all photos by Jan en Rennie Kramer). In the report you can find more information about the observations and the locations they visited.
This weekend Marcia de Graaff, Bastiaan Blaauw and their team from the Dutch-Frisian citizen movement Kening fan ‘e Greide (King of the Meadow), organised a march called “Stoarmrin voor Biodiversiteit” – Storming for Biodiversity.
The Stoarmrin was to be a marsh through the Dutch-Frisian landscape, which ecosystem values are at stake, as is true for many landscapes in Europe. The idea is very similar to the People’s Walk for Wildlife held in London this year. A positive message of concern, with people marching dressed as their favorite flower or animal; in our collective consciousness similar ideas were born. Chris Packham was so kind to sent an inspirational video:
And the Storming for Biodiversity did happen! On Sunday 28 October – in weather that was a lot more lovely than was anticipated with the stormy title. On a chilly but sunny Sunday a few 100 people, and one royal godwit on his carriage, embarked on a 9 km walk around the Frisian town of Burgwerd.
The participants were an eclectic mix of adults, children, artists, scientists dressed colorfully as animals, or simply in boots and a pink skirt – which symbolized hope for a better future for plants, insects and birds.
The march did not make it to Guardian (see below), but was covered on the front page of the regional Leeuwarder Courant. We hope this will be the start of a series of Walks for Wildlife next year. In The Netherlands we are dreaming up a large march eventually gathering at the seat of government in The Hague, so the royal godwit can deliver our own people’s Manifesto for Wildlife.
Exciting news! This week (15 October) we published a paper on our decades-long Bar-tailed Godwit research in the East Atlantic Flyway – these are the godwits migrating from West Africa to the Siberian Arctic.
During the last decades Bar-tailed Godwits experienced changes in the tundra phenology. We detected a chain of effects suggesting that conditions in the temperate zone (that is, the Wadden Sea) determine the ability of Bar-tailed Godwits to cope with the climate-related changes in the Arctic.
The paper in Nature Communications can be accessed here. This paper is the product of the collaboration between Russian, USA and Dutch scientists, the migration watchers of trektellen.nl, and two Dutch groups of volunteer bird catchers – VRS Castricum and the Frisian Wilsterflappers. The paper is based on multiple long-term research programs, of which the benthic survey work by the Royal NIOZ in the Wadden Sea needs special mention.
In this blog called, The natural history of our changing planet, Theunis describes the background of this long-term study, and he looks forward: “I hope that our paper helps establish political will to continue such observations. We should realize that, despite its key value, we cannot just rely on the thousands of hours of unpaid labour by keen amateur bird scientists.”
Again in 2018, during the spring migration season the GFN team worked in Bohai Bay, China, to study Red Knots and Great Knots on northward migration. This year the team consisted of Chris Hassell, Adrian Boyle and Matt Slaymaker. The senior researcher in the project Theunis Piersma visited for about one week.
There are some undoubted positive things happening around the environment in China and on the Luannan Coast currently, and we encourages you to read those sections towards the end of the report, if nothing else.
Ruth Howison, Jos Hooijmeijer and Theunis Piersma report:
The Netherlands is home to over 85% of the northwest European breeding population of the continental subspecies of Black-tailed Godwits Limosa limosa limosa (Fig. 1). Black-tailed Godwits are an iconic meadow bird and the national bird species of The Netherlands. The Dutch population originated in the wet grassland meadows created by many generations of Dutch dairy farmers (Beintema 1986). However, due to intensification of agricultural practices (Kentie et al. 2015, Howison et al. 2018), the population has declined by over 75% since the first population size estimates in the 1960s (Kentie et al. 2016)
For the past 15 years, the RUG team ‘Skries’ (most years consisting of ca. 10 paid field technicians and ca. 10 students and international volunteers) has carefully monitored godwit population events (establishment, nest locations, egg and chick production and postbreeding movements) within what is now a 11,400 ha study area in southwest Friesland (municipality Súdwest Fryslân). In addition, the locations of a small number of black-tailed godwits population have been tracked with solar PTT satellite transmitters (Microwave Telemetry, Columbia, MD).
In 2018, Europe experienced one of the hottest summers on record. Extreme temperature anomalys bring with them extreme weather as heat waves, droughts, and floods, which negatively impact agricultural as well as natural systems. For southwest Friesland, air temperatures in early March dipped below average, freezing most of the countryside (Fig. 2). However, soon May and June followed with maximum daily temperatures exceeding the upper limits of the long term average calculated over the past 28 years.
Using vegetation indices measured at 16-day intervals by satellite imagery (see Howison et al. 2018 for methods) at the level of fields, we tracked the response of the grassland habitat in the province of Friesland. We compared the situation on 10 May 2018 (Fig. 3a), the moment when grass biomass is high, i.e. just before the widescale mowing, with the situation on 14 August 2018 (Fig. 3b), i.e. when the negative impacts of the drought on the vegetation were most evident. Based on this comparison, we mapped (Fig. 3c) where the impact of drought was light or even absent, i.e. where plant growth increased (Green), where drought had a negative impact, i.e. the vegetation index had decreased (Red), and where vegetation showed little change (Yellow).
We then compared two measures of godwit distribution with this quantitative assessment of the impact of drought on the grassy vegetation. (1) By weekly counts of all godwits in all 3014 fields in our study area, we measured the godwit distribution during territory establishment, egg-laying and early incubation (26 March to 22 April 2018). (2) On the basis of the locations of individually colour-marked birds and godwits tagged with satellite transmitters, we quantified the distribution of postbreeding godwits fuelling up for southward migration from 15 June to 15 August (Fig. 3d).
During territory establishment and early nesting, when their movements are necessarily constrained, the godwits in southwest Friesland occurred on meadows which suffered slightly, yet significantly, less from drought than unused grasslands (Fig. 4). However, during the postbreeding period, the godwits concentrated at meadows where little change in plant growth had occurred during the drought (Fig. 3d & Fig. 4). We note also that southwest Friesland suffered more from the drought than Friesland as a whole (comparison of the two right bar in Fig. 4).
The preference of Black-tailed Godwits for fields in southwest Friesland that, later in summer, suffered the least from the drought of 2018, suggests that the godwits are indicating fields with healthy ‘working’ soils, where capillary processes allow the groundwater to reach the plants even when water tables are low. Godwits indicate drought-resilient grasslands.
I recently wrote about the excessive amount of snow in northeast Greenland and how shorebirds are struggling to reproduce, and some risk-takers to survive, this year. My blog received a lot of attention: it was also posted on the popular birding webpage Birdguides, Scientific American wrote an article about it and I was invited to the studio of ‘Vroege Vogels’ for a live interview on Dutch national radio.
Now that it is mid-July, which is when usually the majority of Sanderling and other shorebirds in northeast Greenland hatch, I thought that it would be appropriate to write an update of the situation, as well as answer some questions I was asked.
Was this a record late snow melt? How unusual is the situation?
The time of onset and the progress of the snow melt was not abnormal. It was the amount of snow that had fallen in late spring (April and May), when temperatures along the northeast coast of Greenland are still below 0 °C, which was unusually large. Such a large amount of snow just takes a very long time to melt, even though the temperatures in June were normal (on average ca. 5 °C) and it was sunny. Since the establishment in 1996 of the research station Zackenberg, in northeast Greenland (74°28’N 20°34’W), such amounts of snow have never been documented before.
What is the current situation?
My colleagues from Aarhus university, who are still in Zackenberg, reported that the amount of snow in early July was still excessive (80% of surface snow covered on 10 July). Also, a third dead, apparently starved, Sanderling was found. A few more Sanderlings that were ringed in Zackenberg in previous years showed up, but the number of observed individuals observed is still much lower compared with previous years.
Also, these birds do not seem to prepare for breeding, but forage in small flocks apparently to get into condition to prepare for migrating southwards. On 8 July, Jannik Hansen reported: “There are hardly any Red Knots left in the area. Also many Sanderlings have left, and flocks of 10-20 Dunlins are flying around now.” Jannik estimated that only ca. 15% of the area usually used by Sanderlings to incubate is free of snow (in average years, many clutches would hatch around this date), and possibly 2-3 % of the area used by Dunlins.
Northeast Greenland is very large and remote, so there is not a lot of local information. Luckily, we also collaborate with Johannes Lang and Benoît Sittler and their team who work at Karup Elv, on Traill island (72°29’N 23°59’W) ca. 240 km south of Zackenberg. As in Zackenberg, the tundra surface was ca. 95 per cent covered in snow, in late June on Traill island, but on 12 July it was estimated to be only 50 per cent. So snow in the southern part of the NE Greenland national park seems have melted faster than farther northwards.
Johannes initially also reported that the tundra was very silent with very few birds around, but on 12 July they had already found three Sanderling clutches, which are predicted to hatch around 26 July. Johannes reports that he suspects that the clutches were laid in an area that was still snow covered at the end of June. Three Sanderling nests are very few compared to other years when more than 10 nests would have been found by this date at Traill island. Johannes and Benoît still observe Sanderling pairs which they expect to give up reproduction soon. The researchers did not find more than these three Sanderling clutches this year. Their discoveries however indicate that some Sanderling pairs managed to produce a very late clutch despite the excessive snow and its slow melt.
Were conditions similar this year across the entire Arctic?
The Arctic tundra used by breeding shorebirds is very large and snowfall is often a regional weather phenomenon. The entire east coast of Greenland has experienced a lot of snowfall during late spring which took a long time to melt away. We do not know in detail what the conditions were in other parts of the Sanderling breeding range (Pearry land in north Greenland, Ellesmere island in Canada), which use the East Atlantic flyway.
The conditions on the tundra near Barrow, Alaska, where Global Flyway Network collaborator Bart Kempenaers and his team studies Red Phalaropes, Semipalmated sandpipers and Pectoral Sandpipers was also exceptionally late due to a large amount of snow. Much fewer shorebirds were around, but those that waited for the snow to melt eventually bred ca. 1 month later than average.
In the Russian Far East, from Sakhalin to Chukotka, the spring was also cold and late (Evgeny Syroechkovskiy, personal communication), and so was the spring in parts of the Canadian Arctic (Paul Smith in an interview with Scientific American).
In contrast to the situation in Greenland and Alaska, on the Taimyr peninsula in Siberian Russia Global Flyway Network researchers Jan van Gils, Thomas Lameris and Mikhail Zhemchuzhnikov experience a very warm summer with on some days temperatures as high as 22 °C! So snow has melted fast there and the first Red Knot chicks hatched on 8 July. More details in their blog.
Will there be no reproductive success at all for shorebirds breeding in east Greenland?
Next to the already mentioned four Sanderling nests that were found (one in Zackenberg and three on Traill island), a clutch of a Common Ringed Plover was found in Zackenberg on the same snow free patch of tundra of 7 by 15 meter on which the single Sanderling nest was discovered. The Ringed Plover nest was however already discovered and eaten by an Arctic fox –as indicated by the foot prints in the snow next to the nest location- the day after discovery. Also one of the three Sanderling clutches on Traill island fell victim to an egg predator already. I expect that few shorebirds will manage to successfully hatch and fledge chicks this year in Northeast Greenland.
Is a delayed breeding season a problem?
First of all, it should be noted that it seems that the majority of shorebirds did not even attempt to breed, but instead did not arrive in their usual breeding territories but probably stayed further southwards. The few birds that risked to fly to Zackenberg had difficulties to survive the period with lack of invertebrate food, as indicated by the three casualties and the (very) low body masses of birds we caught at the end of June. The few shorebirds that managed to lay a clutch, did so with a serious delay. Because the emergence of insects depends on the timing of snow melt, both birds and their prey are similarly delayed: so what is the problem with a delayed start of breeding for shorebirds?
I suspect low reproductive success of Greenland breeding shorebirds this year, and possibly also a lower survival. I would like to document this, but I can only do so with the help of many observers. You can count the number of adult and juvenile Sanderlings at your beaches until mid November. Please download the manual here, which is also available in French, German and Spanish.
That the extensive snow cover has impacts on the Greenlandic shorebirds can already be observed. Several observers have reported unusually large numbers of Red Knots and Sanderlings in early July, which suggests that indeed many shorebirds that would usually breed in east Greenland have returned early. Jim Wilson reported on 4 July: “Knots in summer plumage have been turning up in UK in the last week and that is too early – even for returning females.” And Klaus Günther, working in the German Wadden Sea reported that “among some 5.000-6.000 Knots the % of adult birds was 25% two days ago [on 2 July] on Sylt! Normally you will see only 1-3 % adults in summer among the grey juveniles.”
It is difficult to say whether (and how) a population will deal with a year with very low reproductive success. The future will tell. I hope that I may count on your continued support with useful observations of colour-ringed Sanderlings and from counts of adults and juveniles in late summer and early autumn.
Is this phenomenon the result of climate change and may we expect this to happen more often?
Information used in this blog was received from Martin Bulla, Jan van Gils, Klaus Günther, Jannik Hansen, Bart Kempenaers, Thomas Lameris, Johannes Lang, Benoît Sittler, Evgeny Syroechkovskiy and Jim Wilson
A report from the 2018 Dutch-Russian expedition in Taimyr. The team members are Mikhail Soloviev, Anastasia Popovkina, Jan van Gils, Job ten Horn, Victor Golovnyuk, Thomas Lameris, Mikhail (Misha) Zhemchuzhnikov and Maria Sukhova:
“It is always a risky business to set up experiments in the field. And especially when the field site is located in northern Taimyr (76.1 N 98.5 E), in Russia, and when the experimental animals are nesting Red Knots.
On 29 May 2018, when Jan van Gils, Mikhail Soloviev and their team arrived in Khatanga, the last human-populated place on their way, there were still many uncertainties about their field season.
Would they be able to arrange a helicopter flight to get back from the field or will they have to hitch-hike an icebreaker and have a compulsory late-summer cruise through Franz-Joseph Land Archipelago? What will be conditions at the Taimyr field site? And, most important, will there be nesting Red Knots?
Everything has worked out so far! The helicopter flight back is agreed upon. The weather has been good most of the time, sometimes even too good, since 22 °C is not what one should expect at this location.
And the Red Knots apparently do their best to make researchers happy. On 9 June they were singing around the field camp, and within a week the team had identified 14 nesting territories.
On 13 June, Job ten Horn found the first Red Knot nest with two eggs. The next one was found by Jan, on 18 June (even though he was nest-searching in a fog). By 24 June, eight nests had been found and 11 Red Knot males had received radio transmitters. On 1 July, the team was celebrating the deployment of the first satellite transmitter. By now, three female Red Knots are being tracked through the Argos satellite service.
Crane flies started to emerge in the first days of July, and there are plenty around. Right in time, as after several days of dog-weather with snowfall last Sunday the first Red Knot chicks hatched! The weather then has become good enough for some researchers to go for a dip in a lake. But it all changed very quick, and on Friday chicks from three clutches met this world for the first time in snow and frost.
Fingers crossed the things will roll on as luckily onwards. Hopefully the many Arctic Skuas nesting in the area and Arctic Foxes wandering around will find something else to eat.”
By 30 May, the team had recorded 3,776 colour-banded or flagged birds, the majority of which are from NW Australia. They have precisely 1,000 Broome/80-mile Beach colour-band observations, of 321 individual combinations dominated by 273 Red Knots. The total of 876 individually identifiable birds includes birds banded in Australia (Victoria, Queensland, South Australia), Russia (Chukotka & Kamchatka), New Zealand, Thailand, Japan, and Hong Kong, among others.
The team also reports on the state of land reclamation projects (with a port development threatening to take 54 km2 of mudflats). Another issue is cordgrass Spartina encroaching the mudflats, They say: “it has expanded rapidly along the Nanpu mudflats and is now present at all our survey sites. The good news, however, is that this year the problem has been acknowledged by the local government, and a team of workers has been busy clearing out the dead grass to allow better access to living stems”.
By the time they published the final report on 6 June, they had accumulated 4,122 flag and colour-band observations, the highest total since 2015. This includes birds from 21 banding regions and they have seen flags or bands on 14 species. Their total of 1,097 NW Australia colour-band observations is the second highest total in 9 years of visits to the site!
Jeroen Reneerkens of the University of Groningen studies breeding Sanderlings, for the first time in 2003 and since 2007 annually. He works from the Danish Zackenberg Research Station (74°28’N 20°34’W) in NE Greenland that was established in 1996, and is the research base for various experts monitoring the biotic and abiotic environment of NE Greenland.
Jeroen reports about his remarkable 2018 field season:
I study how rising temperatures may affect the reproductive success of Sanderlings in Zackenberg, NE Greenland. Due to a disproportionate degree of climate warming in the Arctic, shorebirds that migrate to the Arctic to breed are strongly suspected to be negatively affected by ongoing climate change. Niels Martin Schmidt and his team have indeed established that the summer temperatures in Zackenberg have steadily increased during the last decades.
The expected consequence of the warming Arctic summers are a mismatch in timing between arthropods (think insects and spiders), and their shorebird predators. Indeed, the emergence of crawly creatures in the pitfall traps in Zackenberg has advanced in the last two decades, but I learned that Sanderlings in Zackenberg did not adjust the timing of their incubation. Puzzling.
So to further study the ecological interactions between Sanderlings and their prey (and the predators of Sanderling eggs such as Arctic foxes), this summer of 2018 I visited Zackenberg for the 13th time. It turned out to be an exceptional season…
Snow, very much snow!
Sanderlings and other Arctic shorebirds start laying eggs when the snow melts, which usually happens in the first weeks after their arrival, around late May or early June. Shorebirds are so-called income breeders, which means that females produce their eggs from locally acquired food. Their food appears only as soon as the tundra soil becomes snow-free.
Snow melts quicker with higher summer temperatures but it’s not that straight forward because climate models also predict that the amount of winter precipitation (i.e. snow fall) will increase. If that is true, more snow may counteract the effects of warming summers on the timing of emerging of arthropods.
Before I migrated north to follow the Sanderlings, my Danish colleagues who were in Zackenberg since early June had already reported that there was a lot of snow on the tundra and warned me that I should prepare myself for a late breeding season. On satellite images of mid-June 2018 the tundra surface was close to 100% covered in snow, and not only in Zackenberg but in the entire Northeast Greenland national park. After a delay of two days due to fog in Zackenberg in which the small chartered planes cannot land, I arrived in Zackenberg on 14 June.
In the last two weeks of June usually most Sanderling are on their nest while some late breeders, or birds whose first clutches fell victim to egg predators, can be found singing or foraging in pairs while the females gather insects to produce eggs. But not this year…
The amount of snow was so extensive, that the majority of the shorebirds in the Zackenberg valley had flocked together in the snow-free area around the field station. Very lean birds were walking between the wooden buildings in the research station and could be approached up to a few meters, probably because they were not willing to spend their last energy and the much needed time to forage on escaping from human researchers.
Catching shorebirds within the research station
It was clear that no shorebirds were going to nest within the next few weeks, if at all this summer. This exceptional situation gave me the opportunity to document the effects of the large amounts of snow on the behavior of shorebirds and their condition.
Usually, food left-overs from the station’s kitchen are discarded via a hose into the nearby Zackenberg river, such that its smell will not attract Polar Bears to the station. However, the river also only started running on 20 June, which is 16 days later than the average date in 1998-2017; a new record. The researchers were forced to get rid of the grinded food remains onto the tundra close to the station. Luckily, it did not attract Polar Bears, but it did attract a flock of several tens of shorebirds, mainly Sanderlings, Turnstones and Red Knots.
This gave me and my Danish colleague Jannik Hansen (Aarhus University) the possibility to catch birds and assess their body condition. We managed to catch 31 Sanderlings, 23 Turnstones and 12 Red Knots. Several birds were recaptured 1-3 times within a few days.
All individuals were in poor condition. Sanderlings weighed on average 44 grams (range: 33.6-54.6 grams). In comparison, Sanderlings in winter in the Netherlands weigh between 50-55 grams and incubating Sanderlings weigh on average 57 grams. It is good to realize that the incubating females have already produced a four-egg clutch weighing ca. 48 grams before they start incubation!
The locally colour-ringed birds were resighted daily near the sewage outlet and between the station buildings near snow edges. I daily woke up and went to bed with sightings of colour-ringed birds just a few meters from my bedroom window. The food waste close to the station was probably a unique opportunity for shorebirds, as there is only one village and a handful of stations in entire NE Greenland. The body masses of recaptured Sanderlings showed that they could maintain or even increase their body mass. But not all of them.
I found two dead Sanderlings near the station who seemed to have starved to death. One of them weighed 34 grams at first capture and only 32.6 grams when recaptured a few days later. It was found without head, weighing 26 grams. The other, un-ringed but intact, Sanderling weighed 31.8 grams which indicates that many of the Sanderlings were in very poor condition, indeed.
I was delighted with the recapture of a Sanderling which I ringed in Zackenberg as a 7–day old chick on 14 July 2012 and was now almost 6 years old. Luckily, with a weight of 54 grams, she was among the few birds in a good condition.
The sewage near the station did not only attract hungry shorebirds, but also served as a feeding tray for the local Gyrfalcons. Jannik and I almost daily observed one of these large white falcons hunting shorebirds, often flying only a few meters over our heads! Although we did not witness a successful attack, prey remains and plucked feathers in the vicinity of the station indicated that either the Gyrfalcon or possibly Arctic foxes were preying on the starving shorebirds.
A non-breeding year?
During the two-week period that I was in Zackenberg, I did not hear a single singing Sanderling and only a few times I heard a singing Red Knot or Dunlin. I observed two Sanderling pairs, which however seemed to have broken up, or at least could not be found again, during the following days.
Also surprisingly few Sanderlings that were locally colour-ringed were observed. Because Sanderlings are very site faithful to their breeding territories, and given that the snow conditions were similar in the whole range of northeast Greenland, I think that the majority of Sanderlings never arrived in Zackenberg but stayed in more southerly regions with better feeding possibilities.
In recent years, Sanderling hatch dates in Zackenberg ranged between 27 June and 30 July (average 12 July). With an incubation duration of 22 days and four days to lay the clutch of four eggs, this implies that Sanderlings usually start laying around 16 June and at the very latest at 4 July. Given that on 27 June all of the Sanderling habitat in the Zackenberg valley was still covered under at least a meter of snow, it is very unlikely that Sanderlings and other shorebirds will breed this year in Zackenberg, or even entire Northeast Greenland.
Request to report the proportion of juvenile Sanderlings within flocks
What are the consequences of a non-breeding season for the Sanderling population? This will depend on the scale at which the snow cover has affected Sanderling reproduction. The Sanderling breeding area is larger than northeast Greenland only, and it is possible that outside the area affected by snow, Sanderling reproduction will be good this year.
I ask for your help to document the effect of snow conditions on Sanderling reproduction and to score the number of juvenile Sanderlings within flocks at your local beaches. I prefer you to repeatedly observe and score the percentage of juvenile birds in the same area between August and November, following a standardised protocol. You can find more information in the manual which can be downloaded below. Download the Sanderling Ageing Manual here.
Klaassen, M., Lindström, Å., Meltofte, H. & Piersma, T. (2001) Arctic waders are not capital breeders. Nature, 413, 794.
Reneerkens, J., Schmidt, N.M., Gilg, O., Hansen, J., Hansen, L.H., Moreau, J. & Piersma, T. (2016) Effects of food abundance and early clutch predation on reproductive timing in a high Arctic shorebird exposed to advancements in arthropod abundance. Ecology and Evolution, 6, 7375–7386.
Reneerkens, J., van Veelen, P., van der Velde, M., Luttikhuizen, P. & Piersma, T. (2014) Within-population variation in mating system and parental care patterns in the sanderling (Calidris alba) in northeast Greenland. The Auk: Ornithological Advances, 131, 235–247.
Schmidt, N.M., Mosbacher, J.B., Nielsen, P.S., Rasmussen, C., Høye, T.T. & Roslin, T. (2016) An ecological function in crisis? The temporal overlap between plant flowering and pollinator function shrinks as the Arctic warms. Ecography, 39, 1250–1252.