January 27th   Leave a comment

Long-tailed duck doing what it does best - 2/3rds of it time is spent underwater when it is foraging

Long-tailed duck doing what it does best – 2/3rds of it time is spent underwater when it is foraging

I was out at Balcomie Beach this morning. Even though the temperature was up a few degrees on yesterday it felt much colder in the open. The wind was from the south-west and very chilly bringing showers with it. Everything must have been taking shelter. There was almost nothing to see that wasn’t out on the sea where there can be no escape from the wind anyway. The long-tailed ducks are still in Balcomie Bay. Four this morning and a few more flying along the coast. Long-tailed ducks spend more time below the water than above it so they can be hard to count. Any scan across an expanse of sea will miss two-thirds of the ducks at any one time. Another problem with counting long-tails is their mobility. At the moment there is concern that numbers of long-tailed ducks are declining seriously across Europe and particularly in the UK. But we only have wintering birds and ducks are notoriously fickle with changing weather, staying put rather than migrating if conditions allow. The Americans call this “frame bias” – where a duck counter in one state might report a worrying decline in a species where a counter in a neighbouring state might report an increase. Overall no problem if you have a big enough spatial frame for the counts and consider the two states as the same population. We also have this problem across Europe. Good counts in some places (Western Europe) and poorer elsewhere (Russia for example). So a decline in Western Europe may be simply a redistribution, with an increase not being recorded in another location. With long-tailed ducks that winter along any stretch of coast right up to the Arctic, regardless of who is there to count them, this may well be the case. Then again a rapid decline of a bird population globally is not particularly unusual these days. I hope it’s just frame bias: long-tailed ducks are one of best Crail winter birds and I love being able to see them every time I look out to sea.

There was a white-billed diver out at the Isle of May on Wednesday. I have been checking the sea regularly since then in a forlorn hope of seeing this very rare species. The last ones I saw were 11 years ago in the high Arctic of North America, and one this far south is very unusual indeed. I have only seen our usual red-throated divers in the last few days.

Red-throated diver (sadly not carrying a banana which is what a white-billed diver looks like)

Red-throated diver (sadly not carrying a banana which is what a white-billed diver looks like)

Posted January 27, 2013 by wildcrail in Sightings

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