An update on the progress of the exceptionally snow-rich breeding season in northeast Greenland

On 20 July 2018, Jeroen Reneerkens reported:

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.

Snow cover Zackenberg in three years
Large annual variation in snow cover in the Zackenberg valley. Photos taken from the same position on 10 June in 2010, 2013 and 2018 (source: Greenland Ecosystem Monitoring)

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.

Snow in Zackenberg summer 2018
Extensive snowpack in Zackenberg, northeast Greenland in summer 2018. Photo: Jeroen Reneerkens

Still, Jannik found a Sanderling female incubating a clutch of four eggs on a snow-free patch of ca. 7 by 15 meters. By briefly floating the eggs in water, he could estimate that it was incubated for approximately 3 days, which would indicate a hatch date of 28 July. Only 5% of 707 Sanderling families that I monitored between 2003 -2017 hatched on 28 July or later, so this is very late. In most cases in earlier years such late clutches will represent replacement clutches of pairs whose first clutch fell victim to egg predators. It remains to be seen whether the single clutch found in Zackenberg survives until hatch. We have shown before that early in the summer, when the area of tundra covered by snow is still large , clutches run a larger risk to get eaten by egg predators, probably because the snow-free area in which predators search for prey is smaller.

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.

Sanderling Zackenberg 16 June 2017_in_landscape
A Sanderling on the tundra with less snow, Zackenberg 16 June 2017. Photo: Jeroen Reneerkens

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.

familie Kanoet
Red Knot adult and chick. Photo: Jeroen Reneerkens

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.

Kanoet juveniel strand
Few juvenile Red Knots should be expected to appear along NW European wetlands in 2018. Photo: Jeroen Reneerkens

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 expect that the arthropods will appear late and very synchronously, causing a short but very high abundance of insects. In such cases, chicks will have a very short period only to profit from this burst of insect abundance. We have shown that in years with short-lasting peaks of arthropod abundance, Sanderling chick growth was relatively poor.

What is the effect on the shorebird populations?

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.

Juveniele drieteenstrandloper
Juvenile Sanderling. You can help monitor this year’s reproductive success by counting adult and juvenile Sanderlings in flocks at your local beaches. How to do that? You can here download a manual in English, French, German or Spanish. Photo: Jeroen Reneerkens

Is this phenomenon the result of climate change and may we expect this to happen more often?

It is impossible to say whether the exceptional amount of snow this year is the result of a changing climate. However, warmer average global temperature will cause a higher rate of evaporation, more water vapour in the atmosphere will result in more precipitation in Arctic regions. If this precipitation in the Arctic falls in winter or late spring, it will often be in the form of snow. Climate models, predict that global precipitation will increase but that changes in precipitation will not be evenly distributed. Some locations will get more snow.

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


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