Sunday 26 May 2019

Of Sanderlings 25th May 2019

I confess to having a bit of a liking for Sanderlings. They are diminutive waders, phenomenal travellers that normally make their home on large beaches and open seashores with the sound of wind and wave as a constant accompaniment to their existence. Much of their time is spent running back and fore like clockwork toys on twinkling black legs in front of the incoming waves and then chasing the retreating wave back down the shore to seize any exposed prey. In this habitat they are usually to be found in flocks, their tiny, predominantly white bodies, where sea meets sand, easily mistaken from a distance, for blobs of wave froth.

Often they are found with Dunlins which are a tad smaller and have a noticeably longer, slightly curved bill compared to the Sanderling's straight, stub ended, black bill

May is the month when Sanderlings migrate northwards from their winter homes which can be anywhere from England southwards to southern Africa, embarking on a flight of almost heroic proportions to Greenland or the tundra of the high Arctic in northern and central Siberia. They time their arrival to coincide with a short window of opportunity spanning around eight weeks in which to breed before returning south, retreating from the onset of cold. May is also the time when they appear in less familiar habitats such as Farmoor Reservoir, where birds arrive as they cross England, taking a short cut northeast, arriving at the reservoir from origins much further south. Quite a number must do this, as today for instance, small flocks or individual Sanderlings have been reported inland from Yorkshire, Berkshire, Leicestershire, Staffordshire and Nottinghamshire.

At Farmoor they find the concrete shelving on either side of the reservoir's causeway the next best thing to their normal beach habitat and being supremely sociable, if travelling alone, will team up with other similarly small waders and probably migrate onwards with them as well, given the opportunity. Today for instance one Sanderling made up a mixed flock of five birds, with the others being two Dunlin and two Ringed Plover. All three species breed in differing  northern latitudes and will eventually part, each on a journey to their own separate destination but for now five pairs of eyes are better than one to look out for danger and predators.

Ringed Plover and Sanderling

Having no seashore waves to chase up and down after, the Sanderling settled for feeding along the edge of the reservoir with the other waders, picking up minute prey. Its mottled, predominantly grey plumage making it well nigh invisible from distance as it pattered along the sunlit and similarly mottled concrete. Of the three species here today the Sanderling was the most active and was, for the majority of the time, constantly looking for food but compared to its normal hyperactivity could be described as almost relaxed, only resorting to running at speed when approached too closely.

By my stepping back or sitting quietly on the retaining wall of the causeway and showing no overt interest the flock of waders became still. Of the three species, the Ringed Plovers appeared almost lethargic compared to the other two, covert in their behaviour, stopping and then taking a few steps in typical cautious, circumspect plover fashion,  sidling  up the concrete shelving to stand by some reassuring vegetative cover or even sit quietly, taking a chance to gain some rest before their marathon journey recommenced. It is as  if they have supreme confidence in the camouflage that their sandy brown upperbody gives them, turning them almost invisible against the similar colour shades of the concrete. A surprisingly effective camouflage until they move.

Ringed Plover
The two Dunlins on seeing the Ringed Plover squatting on the concrete joined it. Small waders will often do this on migration here, stimulated to copy another individual's action, be it preening, resting or feeding.

It was contagious and the other Ringed Plover and the Sanderling also stopped, to pause in their seemingly endless quest for sustenance and stand quietly but it did not last for long and soon all five of the flock were off again, in a line, heads bent to the shoreline in search of food.

The predictable regular passing of people walking the causeway on a sunny Saturday morning kept the small flock forever vigilant and active, although often going  un-noticed by the passers-by and it was only in times of absence of this human traffic that the birds felt inclined to pause.

There have been a good number of Sanderlings passing through Farmoor in the past two weeks and maybe there are more to come. In the Arctic it is still inhospitable so the timing of arrival there must be exactly right but even so the birds only tarry for a day or two here and then they are off northwards again, maybe to stop off somewhere else in transit.

This procession of Sanderlings through Farmoor in May also gives an opportunity to see them in less familiar plumage than their grey and white winter feathers. A body moult, commenced  before they leave their winter homes, means the birds have fresh feathers when they arrive here in May. Sanderlings arriving earlier in the month are predominantly white and grey, due to the  pale fringes of the newly acquired feathers on the head, breast and upperparts being extensive, making the bird appear mottled black and white, sometimes with a tinge of chestnut showing through on the sides of the head. As the month progresses the fringes wear away, so later arriving birds such as the one today and those of yesterday show more chestnut on the feather bases. As the wearing process continues they eventually become a rich chestnut on their head, upperparts and breast band, taking on an attractive chestnut and white appearance which is not seen that often in Britain.

An exceptional adult Sanderling in full breeding plumage taken a few years
ago in May at Farmoor Reservoir
By the time they arrive on their breeding grounds they will be in this full breeding dress although many, possibly younger birds in their first two years of life, do not become so intensely chestnut and remain a combination of white and chestnut to varying degrees.

This window of opportunity to see Sanderlings at Farmoor in their variable breeding plumage will only last for a few more days possibly into the first week in June and then it is over until some Sanderlings touch down at Farmoor on their return journey from the Arctic. However, by then, their plumage will be worn and frayed and not show the freshness and splendour that it does at this time of year.

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