Saturday 3 March 2012

Wandsworth Caspo

On Saturday I took the boys out for a trip along the river to Wandle Creek and Wandsworth Park (where there's a playground they like). I also hoped there was a chance, even if only a small one, of reconnecting with the Caspian Gull I saw last week at the London Wetland Centre (LWC) on this stretch of the Thames since it's only a mile or so downstream. Scanning some way up river I was still stunned to see what looked like a first winter Caspian Gull sitting with other gulls some way upriver. On trips out with the boys I only take bins and a camera so no scope so, especially in the light of what had happened at the LWC, I tried to chivvy the boys along a bit to get there before it flew off. Luckily it was still there when I finally got opposite it and could see it was a Caspian, but a different bird from the one I’d seen last week at the Wetland Centre.

It was a big bird, looking bigger than nearly all of the Herring Gulls and standing taller than all of them. The photos below show the 'Caspian basics' of four colour pattern (white head and underparts, grey mantle, mid-brown wing coverts and dark brown primaries). It also shows the grey neck shawl, solid brown centred greater coverts with white fringes, solid brown tertials with pale tips and very thin fringes. The bare parts show a bicoloured bill with the end third dark and the basal two thirds paler, but with dark cutting edges. The legs are long and pale pink.


Below shows the small headed and big chested appearance.It also shows the mantle pattern with a mix of feathers with thin shaft streaks and thick white tips and the blockier 'diamond pattern' scap feathers.

Showing the blackish tail band, white upper tail and rump. You can also (just) see the secondary pattern of dark centres with pale fringes.

Shows tertial pattern with worn pale tips. The tips of the inner ones especially are very worn (the pale parts of feathers always seem to wear more quickly than darker ones - some effect of melanin protecting the feather?).

On the way back a call from a bush revealed this Chiffchaff. This is the first I've had around here this year, but presumably an over-wintering bird rather than an early migrant.


I don't think this is the first Caspian for the patch - I'm fairly sure one was reported here a few years back - but it is the first one I've found or seen here. This is one bird I've been very keen to get on this patch so I'm pretty excited! With the Barnes bird, plus those at Beddington and Rainham (and probably elsewhere) there is a good number of Caspos in London at the moment.

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