Thursday, October 21, 2010

Autumn Migration

The Spring migration in SW Iberia is always very poor except for birds which are arriving to breed here. Those moving into central and northern Europe tend to cross the Straits of Gibraltar at Tarifa and move on immediately propelled by hormones and the urge to breed. The autumn migration is normally much better with huge numbers of both passerines and raptors drifting more slowly down the west coast of Spain and Portugal towards Cabo de São Vicente (the most south-westerly tip of Europe) where they tend to linger and feed before moving east to Tarifa for the final "jump" to N Africa. In previous years the raptor movement (from the traditional watch-point at Cabranosa) has been fantastic  -  I recall being there one day in October a few years ago and seeing 1,900 Griffon Vultures in one flock with a supporting cast of flocks of Short-toed Eagles, Booted Eagles, Honey Buzzards, etc all in good numbers.

Shots of two juvenile Winchats (taken through the window while sitting at my desk!).

This autumn the migration has been the worst I can recall in fourteen years here. I spent two mornings at "The Cape" searching for the elusive Dotterel which I knew were there (but failed to find) and during that time the only raptors I saw were Common Kestrels (probably resident, although migrants from N Europe do pass through). Closer to home (my garden, and local "patch" at Ria de Alvor) there has been a dearth of passerines. Pied Flycatcher is usually the commonest passerine at this time, but this year there were very few. The low numbers is confirmed by the captures at the ringing station at A Rocha.

Northern Wheatear in agressive posture  -  I was too close.

Northern Wheatear, probably of the Greenland/Iceland race leucorhoa.

There was a brief "window" at the beginning of October when there was a rush of Pied Flycatchers (I counted about twenty in my garden one morning) and a very large number of Northern Wheatears. Whinchats (mainly juveniles) were present in smaller numbers, and what a delight they are.

This marked reduction in numbers of birds compared to previous years is a cause for concern  -  I wonder what the cause is?

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