Turnstone plumage

We are lucky to have a small population of Ruddy Turnstones, Arenaria interpres, in Scarborough. They spend most of the year here, except for the summer when they fly up to the Arctic to breed. Before they leave in May, they have usually moulted into their gorgeous breeding plumage (below).

Ruddy turnstone (Arenaria interpres), Scarborough. 7th May 2018.

Their plumage gradually changes over the course of the year. They are already starting to get a bit of breeding plumage in April (below).

Ruddy turnstone, 16 April 2021.

Almost all Turnstones wintering on the seaboard of western Europe are said to breed in Greenland and north-east Canada. It’s hard to believe that the little things you see around the harbour, fly all the way to Greenland and back! And they bring their new offspring with them! A few don’t make it back, but remarkably, their migration to and from the Arctic breeding grounds does not cause much mortality. More die hanging around their overwintering grounds apparently! Some seem to lose toes, unfortunately. Others live dangerously, scavenging for left-over chips or ice cream (see below) in the car park by the harbour! As I described in a previous blog.

Ruddy turnstone supping up some ice cream or yoghourt? 19 Nov 2021.

Ruddy turnstones usually return to the same site every year; their winter home. A study carried out in Hartlepool, found that most of the local turnstones survived between spring and autumn and came back to the same feeding area (Burton and Evans 1997). In Scarborough, they mostly roost in the outer harbour, on a wooden walkway by the yachts (below), out of the wind! These ones had just returned in August of this year.

Turnstones just returned from the Arctic? On 9 Aug 2021.

The patterns of Ruddy Turnstone have been cited as examples of disruptive camouflage. Most waders show countershading to some extent, i.e. they are generally darker on the back (dorsal side) than they are on the undersides (ventral side). This shading compensates for the greater illumination which undoubtedly falls on their backs; particularly when they are in the high Arctic, I would imagine. Perhaps, it also helps the bird to blend more easily with its background? Not something that happens when they scamper about the harbour in Scarborough!

Adult turnstone in breeding plumage. By © Hans Hillewaert, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=15222118

Completely white undersides can contribute to more efficient foraging, presumably because the bird looks no different to the sky when a fish glances upwards!

Ruddy turnstone. 19 Nov 21.

Dark colours, especially those produced by melanin, protect feathers from damaging UV radiation that might otherwise accelerate the rate of feather wear. The pigments occur in granules that are restricted to the outermost layers of the feather keratin. There are different types of melanin. Eumelanin is responsible for the browns, greys and blacks Phaeomelanin produces various shades of brown, chestnut and red. Presumably, the colour changes are mediated by day length.

Ruddy turnstone,1 Oct 2021.

Ruddy turnstones are a bit different from some other types of waders, in that they have individual markings. Wintering turnstones have individually variable plumage which remains the same from year to year. This enables the birds to be recognized by their neighbours (Whitfield, 1986). This means that they are rather variable (see below). However, the variation seems to be much easier to tell apart when they are in breeding plumage.

Head and breast pattern of adult female, male and juvenile Ruddy Turnstones in breeding and winter plumages. Illustration by Tomasz Cofta (Meissner and Cofta, 2018).

In winter plumage, they are I think, quite difficult to tell apart. I am not at all confident about sexing them! Females seem to have more of a dark ring of feathers around there neck. Is this individual (below), a female?

Ruddy turnstone, female? 7 Nov 2021.

And when they stretch their necks (see below), they look rather different! This one looks a bit like a juvenile, but I am not at all sure!

Ruddy turnstone, 21 Nov 2021.

Although they presumably have no trouble in recognising each other, it think it is almost impossible for humans to spot individuals in non-breeding plumage. That is why people have ringed them in the past (below). A very handy way to recognise each bird, although whether the turnstones like their plastic bracelets is harder to say!

I spent quite a lot of time looking at the turnstones during lockdown. They were a great consolation and a pleasure to watch. I even fed them (muesli) sometimes! I will probably need a few more lockdowns to be able to tell individuals apart, unless they have some obvious feature, like a set of coloured rings, or a missing toe, or toes (below). This individual managed to survive for quite a long time, but whether she is still alive I don’t know. I’ll keep an eye out for her.

Ruddy turnstone with missing toes, 13 March 2021.

Turnstones are resilient and adaptable; useful characteristics to have in this human-dominated world. They are not tame, but they manage to eke out a living around our feet. The fact that the same individuals return to the same local patch each year makes them feel like family! I would love to travel to Greenland in June and see what they get up to there! It’s a side to them we don’t see here. And wouldn’t it be lovely to see their chicks! I’m not sure how many

turnstones there are in Scarborough (20 or 30 at a peak?). Perhaps some birders will have counted them. And do they move about and visit colonies up and down the coast? I would expect that of juvenile birds.

Turnstones on 11 Feb 2021.

Let’s finish with a few portraits of some of the individuals who call Scarborough home.

References

Burton, N. H., & Evans, P. R. (1997). Survival and winter site-fidelity of Turnstones Arenaria interpres and Purple Sandpipers Calidris maritima in northeast England. Bird Study44(1), 35-44.

Ferns, P. N. (2003). Plumage colour and pattern in waders. BULLETIN-WADER STUDY GROUP100, 122-129.

Meissner, W., & Cofta, T. (2018). Part 13: Ageing and sexing the Ruddy Turnstone Arenaria interpres. Wader Study125(1).

Whitfield, D. P. (1988). The social significance of plumage variability in wintering turnstone Arenaria interpres. Animal Behaviour36(2), 408-415.

Whitfield, D. P. (1986). Plumage variability and territoriality in breeding turnstone Arenaria interpres: status signalling or individual recognition?. Animal Behaviour34(5), 1471-1482.

One thought on “Turnstone plumage

  1. One point I wd add to your lovely tribute to your Scarborough neighbours is what extraordinary catholicity they have in diet which includes dogs hit, human vomit and one on Anglesey that was infamously recorded eating a human corpse. But my favourite reference is to one eating inside the thoracic cavity of a wolf. Makes a nice reversal of the expression to wolf something down. But my main point is the versatility of the beak which I have come to realise is rather like a dipper’s. And serves as a similar kind of all purpose awl/chisel toolkit. Also like dipper’s they are rotund, immensely Hardy and full of inherent character or charisma. I think their shared dumpy shape is part of their appeal to us. Thank you Ray for some great photos and reflections.

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