Tuesday 20 January 2015

Cold enough for snow

The sand was frozen solid. The usual shifting and sinking associated with walking on sand gone, replaced by a cold hard mass with frozen tufts of maram grass and silvery white patches of frost. It was a very cold, blue dawn. As the light brought definition to the sand dunes, the beach and the pale blue ocean, just one cloud became tinged with pink. On the sand and pebbles of the beach below the dunes the light also revealed our whoosh net, set under the cover of darkness. With the dawn birds started moving around the beach, a wave of small passerines moving as one, settling on one patch of sand before lifting, dashing off, turning sharply and landing on another. Small waders woke from their roost on the angular rocks of sea defences and started the same process, settling down in one area, running with legs working overtime before lifting off again. Large gulls and cormorants streamed by, ignoring the dance being played out on the beach. The team of ringers waited patiently for birds to settle in the catching area. When one or two came in, it was then a mind game of when to catch. Wait for one more and risk the whole flock lifting off at the last moment? 

Waiting patiently among the sand dunes

Finally the moment arrived and the net fired. It was then a dash down the beach to stop any birds wriggling out from under the net and to get them out. It is a small group of snow buntings that we have caught. A scare breeder in Scotland, large numbers from Iceland and Scandinavia come to Britain in winter where their flocks and often confiding nature brightens any winter’s day along the cold coast. 

Most of the birds caught today were already ringed. While many may see that as a disappointment this is the most important part of ringing. Re-trapping ringed birds provides us with the detail on movements, longevity, survival – all the answers to why we ring. It can also help with the process of ageing and sexing birds. With snow buntings however the process is not just about ageing and sexing, it is also about identifying the race the bird belongs to. There are four races of snow bunting, with those wintering in Britain falling into one of two; the nominate nivalis which breeds in Arctic Europe, North America, North West Russia, Greenland and Scotland tends to be much whiter than insulae which are darker and breed in Iceland. 

Adult female nivalis
Juvenile female insulae

Race identified the next job was to check whether it is male or female. One might assume straight off that the whiter individuals are all male, but with females of nivalis showing extensive white amongst the mottled sandy brown wash of their winter plumage it is not always that clear cut. It is under the wing that the secret is revealed, with males having a clear inky black along on the primaries, almost like they have been dipped in paint. While in females it is much more washed out. Today’s catch, in keeping with the past few, are mostly female, throwing up interesting questions about the sex ratio of wintering flocks. Ageing is not as easy and a question of looking at feather quality, shape of patterning and wear of the feathers.

The only male caught, an adult insulae

Ultimately it was a privilege to be standing under a bright winter’s blue sky, the sand slowly defrosting beneath our feet, discussing and learning about these beautiful little buntings.

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