December 14th   Leave a comment

It gets harder and harder to find the time to get out and see what is happening around Crail as Christmas approaches. The shorter days, the bad weather and today the strong winds all conspire to make observations difficult. I am minded that this is the same problem that the birds face except they have more serious consequences of failing. We have had strong southerlies all day today, with big seas and seabirds pushed in close to the shore. I had a great northern diver going east past Crail this morning. Its usual laboured flight was quite inspired in the gale. Unusually for the time of year there have been gannets passing close in all day – I have had Decembers with only one or two for the month – the birds today were mostly first winter birds.

First winter gannet past Crail today

First winter gannet past Crail today

A winter male house sparrow with time on his hands

A winter male house sparrow with time on his hands

Denburn was very quiet this morning. Somewhat sheltered from the storm but bare and small feeling now that the leaves have gone and the houses can be seen crowding round. On winter days like these when there are strong winds and it has been relatively warm (the last 4 days have only had minima of 11 degrees or so) birds just hunker down in a bush and rest through the day, conserving energy and only feeding for a small part of it. The house sparrows epitomise this, gathering in daytime roosts after feeding in the early morning. There were tens gathered in a big Thuja bush behind my garden even by 11 this morning. I could hear them cheeping away but they were all invisible. Every so often they would go silent, probably in response to a potential sparrowhawk or cat passing, before resuming their chorus. Sparrows loudly cheeping from a daytime roost in the middle of a winter’s day must be one of the best indicators of a happy, well fed population: time and energy to spare.

There has been the usual winter flock of oystercatchers feeding on the short grass lawn above Roome Bay this week at high tide. Oystercatchers are surprisingly versatile and can feed happily on worms in turf and on ploughed fields. In some populations only the younger birds or poorer competitors feed away from the shore during the winter. There is a greater risk of predation and even parasitism. I think more or less all the oystercatchers that winter in Roome Bay feed regularly on the grass so I don’t think it is a desperate strategy for them. They frequently get disturbed by dog walkers but this probably keeps down much more serious disturbance from predators. When back on the mud oystercatchers take either molluscs or worms. There will be individuals that specialise on either and for those that feed on molluscs there are even specialists that hammer open shells and others that lever them open. These specialisms are a consequence of early selection of a particular feeding area where one type of prey might be more common. As an individual gets more practiced and efficient at harvesting one particular prey type it then makes sense for it to keep playing to its strengths. And because oystercatchers like to flock together, if one or two birds favour turf feeding at Roome Bay each year then others may pick up the habit too. It’s not quite transmission of a cultural trait, but something a bit like it.

Oystercatcher with a cockle

Oystercatcher with a cockle

Posted December 14, 2013 by wildcrail in Sightings

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