June 19th Why so many rings on a redshank?   Leave a comment

I am in Africa and disconnected from Crail for now. But I was brought back home by a post about a Crail redshank – someone wanted to know what was the point of all those rings that I use?

I remember thinking exactly the same thing when the BTO and the Wader Colour Marking scheme gave me my combinations to start my PhD study on redshanks in 1989. Six rings? Two of them giant blue ones? And a metal one? What was the point?

25 years later I know why and I realise the wisdom of the idea. For a start we put colour-rings on because we wish to identify individuals. This way you don’t need to recapture them to know who is where and we can string together sightings from Iceland to Scotland to Africa as redshanks migrate. Birders and photographers can record colour-ring combinations, report them into the colour-ringing scheme and get to hear the individual adventure of the bird they have seen. And those of us studying the birds get important data points on the places used and things like speed of migration, age of breeding and survival. The bird in the photo is YNGN – Yellow Black Green Black. I ringed this bird on the 21st March 2011 as a bird in its first winter (i.e. born the summer before) on Crail harbor beach (east Fife, Scotland) using a net strung across the harbour entrance. The redshanks of Crail make use of the floodlit, water free harbor on cold low tide nights, and if you are lucky all fly out of the harbor using the quickest route. Most nights they don’t of course but that’s another long and cold story. YNGN is a harbour regular feeding there day and night and often gets photographed because people can get close to it, looking down from the harbor walls as it feeds on the mud below. I caught it again in 2012 and 2014, which was the last year I was regularly catching at Crail. So with the colour rings I know that it is 8 years old (27 years is the longevity record) and that it always feeds in a small area of Crail around the harbor. Although it hasn’t happened yet with this bird, other Crail birds have been seen all along the eastern Scottish coast to Aberdeen, the May Island and two in Iceland where most probably breed. So I can connect our Scottish east coast population together with the Icelandic population, and I am getting an idea of their survival rate. All very useful when thinking about conserving our declining populations of redshanks.

OK I hear you saying, but why so many rings – surely one or two would do the job? And what about those big blue ones. Well, believe it or not, there are tens of people that study redshanks around Europe and they all need to have a scheme identifier. This allows a scientist like me to use my own colour-combinations without fear of duplicating someone else’s and messing up their study. And my redshank move all over Europe as do theirs. I put two tall blue rings below the knee on all my birds so that when someone reports a sighting, the scheme identifier knows it is my bird and they can put me in contact with the person who sighted it – as in this case – to tell the story. And of course I get that important data point. The four rings above the knees, two on each leg, are in different combinations for each individual. I don’t give names to my birds but YNGN is as individual to me as my dog – I see it nearly every day during the winter as I walk around the shore of my village (with my dog). This was never the purpose of colour-ringing the redshanks, but it is a pleasant consequence. YNGN is one of my long term neighbours and gives me as much a sense of home as all the familiar people I share Crail with.

I colour-ring the redshanks because I want to measure their survival rates and determine how often they are killed and eaten by birds of prey. I have published 27 papers on redshanks to date giving us vital information of how they live and die in our increasingly man-affected and shrinking habitats. Redshanks are pretty resilient but still we need to know where to conserve areas and when to minimise disturbance to them to give them a fighting chance of survival into the future. One of the papers I am most proud of was a study where I looked at the effects of all those rings on redshank behavior and their survival. After all, if I have to use all of those rings I should at least know their detrimental effects if there are any. I compared the feeding rates and the location and time spent feeding for birds with no rings and those with lots of rings: I couldn’t find any differences at all. If rings upset redshanks then we would expect them to have to compensate by feeding more or taking risks and feeding in dangerous areas. But most significantly I compared the number of colour-ringed redshanks that were killed by sparrowhawks and peregrines through the winter with those taken but not ringed. I was lucky enough to be working on an estuary close to Crail where many redshanks were killed each winter – it was a little like the Serengeti in miniature with redshanks the wildebeest, sparrowhawks the leopards and peregrines the lions. Because so many were being eaten (the population wasn’t affected by the way – in years with few redshanks the predators ate other things – again like the Serengeti) I was able to really see whether colour-rings affected the probability of being targeted and killed. I would have been able to detect even a 1% difference in survival rate over the winter. You might expect all that redshank bling might attract a raptor or reduce a redshank’s ability to escape. But I found no effect at all (the difference was statistically insignificant and actually opposite to what I expected).

So, I have moved on from my initial reaction of horror at so many rings on my redshanks to an appreciation of them. I can easily identify individuals – and so can everybody else. The redshanks are not harmed by them and we gain useful information for a long time. I hope to see YNGN for another 20 years around Crail. It will still be in Crail harbor then if it is still alive, still being photographed and still being reported to me via the colour-ringing scheme to add to my survival study. And who knows – those conspicuous rings may lead to an Icelander spotting it in their field so I will find out its summer home as well as its winter one.

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Posted June 19, 2018 by aboutcrail in Sightings

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