June 20th   Leave a comment

The sea has been fairly calm for most of this week. In the evenings this means that you can see all the seabirds going in and out of the Forth from Crail. Hundreds every minute: puffins, razorbills, guillemots, gannets, kittiwakes and shags for the most part with the occasional manx shearwater passing by on an anti-clockwise circuit of Britain from a colony somewhere on the west coast. Occasionally there are big groups of all these species gathering where there are fish. Harder to spot – often these groups are comprised of dots even through my telescope – are the cetaceans below them. Today there were a couple of porpoises – with their distinctive blunt heads and stubby dorsal fins just visible. They come to the surface much less often than dolphins. Porpoises have a problem with the bottle-nosed dolphins: the dolphins are frequently aggressive to porpoises and will strike and kill them, probably because they compete for the same resources. Porpoises are much smaller so have to keep out the way, or keep their body mass lower to enable them to manoeuvre out of trouble more easily. The result is that porpoises have lower fat reserves in areas where there are dolphins and are more likely to starve in poor conditions: a double whammy. It pushes the porpoises into a more marginal existence. We think the same thing is happening with sparrowhawks and sparrows. Sparrowhawks as the name suggests have sparrows on top of their menu and so sparrows can only thrive where there is plenty of cover for them to escape to, and when they can make a rapid escape. Like the porpoises they keep their mass low to maximise their ability to accelerate out of trouble, and like the porpoises they suffer a double whammy of higher starvation risk when conditions are bad in winter. Natural history is full of such interactions that make it so interesting and the best puzzle of all.

Kittiwake - they are busy feeding chicks now on the May island so are passing Crail constantly

Kittiwake – they are busy feeding chicks now on the May island so are passing Crail constantly

Posted June 21, 2014 by wildcrail in Sightings

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