February 3rd   1 comment

The weather today was spectacular, running through sunny early spring weather in the morning to a howling gale by the afternoon. I saw a dolphin – probably one of the bottle-nosed dolphins we see most often off Crail – from Roome Bay in the morning. It was chasing fish, its dorsal fin appearing out of the water only occasionally, but rapidly and erratically as it twisted and turned under the water. I don’t think it was with other dolphins, which is usually the case, but it is often hard to tell. I think the number of dolphin sightings from Crail is mostly a function of how calm it is (and of course how many people are out and about looking out to sea). In the winter the choppy sea disguises dolphins surfacing very well. You only really see a dolphin if you are looking at something else through binoculars and one surfaces in the same field of view. Today I was looking at a seal in the foreground. But in the summer when the sea gets much calmer then it is impossible for a school of dolphins not to be noticed passing Crail, even if they are as far out as the Isle of May.

Bottle-nosed dolphin

Colour-ringed Redshank

I was catching redshanks this afternoon. The tides are high this week so the redshanks have been concentrating on Roome Bay Beach in the afternoon, with thirty or so birds feeding on the wrack or on the beach. Very high water pushes out all the seaweed flies from the kelp beds at the top of the beach as even these high reaches get submerged. The beach then goes almost black from the flies. And this time of year it is cold so they are sluggish and easy for any hungry bird to pick up tens of flies in a minute. So the redshanks were feeding at a very high rate (distracted), very close together (lots of potential targets), and were prepared to return to the same area when disturbed (predictable): just perfect for catching. My traps are simple net cages in two halves. The top half is folded back, but spring loaded. A catch keeps the top folded back, but this catch can be easily dislodged if a bird steps on the string attached the catch that lies across the bottom half of the trap. Think of a giant old fashioned mousetrap, but with a harmless net thrown over the bird when the catch is dislodged. I have become a great fan of these traps for catching redshanks this winter. Quite often the redshank doesn’t work out what has happened immediately and that it is trapped, and even the other birds around it also often don’t respond. If you are quick and run down to the trap immediately the trapped bird only gets very agitated because of your approach. It is a very safe and relatively stress free way of catching birds. That said, wild birds are being caught and handled which is of course must be very stressful for the birds concerned, so any way to minimise the duration of this is good.

I had amazing luck today catching. Not many redshanks, but three birds that were already ringed. I caught an oystercatcher and a redshank both with a British ring, but most special was a purple sandpiper with a Norwegian ring on it. The purple sandpiper also had colour rings on it. Another scientist in Norway must be doing a study like mine, needing individually recognisable birds in the field as I do with my redshanks. I counted my blessing though – purple sandpipers have shorter legs than redshanks and have a crouching and shuffling way of walking so the colour-rings were barely noticeable. It would be a nightmare to have to systematically find and identify individuals in the field. And bear in mind they frequent the rocks amongst the surf far out from the shore most of the time. One of the rings was what is called a “leg flag”; you can see in the photo that these are colour-rings with a flap sticking out to increase visibility and in this case to allow a number to be put on them.  The study may be colour-ringing hundreds of birds and this is an easy way to generate a lot of different individual combinations. I use unique sets of different coloured rings but then I only have several hundred permutations before I run out of different combinations. Leg flags get round this limitation, but I am not a fan of them because they protrude out from the leg considerably. I am reasonably happy to temporarily stress birds to catch them and colour-ring them so I can follow their fortunes as individuals over many years, but I am wary of saddling them with anything that might affect their flying or foraging performance, and so their long term survival.

Colour-ringed Purple Sandpiper

I will submit the ring numbers to the British Trust for Ornithology which keeps the database of ringed birds in the UK, and also to the equivalent organisation in Norway, and they will let me know when and where the birds were ringed. Watch this space! The oystercatcher’s ring was very worn, with the last bit of the number nearly illegible – I am hopeful that this means that the oystercatcher is very old. They can live 25 years or more, so this bird may have been in Crail much longer than me. Both the redshank and the purple sandpiper were birds in their first year so will have been ringed either on their breeding ground or on passage this autumn.

Ringed Oystercatcher

The whole afternoon reminded me of how connected Crail is to the rest of the country and indeed the rest of Europe via its birds. Among the stay at home resident birds there are just as many international travellers spending a few days or a season with us. Many Crail birds live two lives, spending a season with us and then another in another part of the world – swallow in South Africa for the winter, for example, and purple sandpipers in the mountains of Norway for the summer. The Roome Bay black redstart is another example, and I think it finally has moved on, probably back to continental Europe in readiness for the start of breeding next month.

Posted February 6, 2011 by wildcrail in Sightings

One response to “February 3rd

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  1. Great catch! That oystercatcher surely looks monstrous!
    Tack care/Johan

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