Sunday 27 May 2012

Bonaparte's find!

The incinerator outflow at Cross Ness

Last weekend, Rich B found a 2cy Bonaparte's Gull at Cross Ness, London - essentially the first London record of the species. I had a busy week, and didn't get chance to head out east for the bird, so planned to do so this time out.

I met Rich at Canada Water a short while after half 7, and we headed over to Cross Ness straight away. It didn't take long to reach the incinerator outfall, where about 60-70 Black-headed Gulls were feeding. Among them, we quickly located a first-summer Bonaparte's Gull, although the apparent change in appearance from the previous weekend was vast. It had seemingly developed a partial hood in a matter of a few days - Rich had last seen it on Monday, when it still looked wintry. We tentatively 'joked' that it could be a new bird, but realistically assumed it must be the same despite the remarkable change in appearance - why would there be two Boners on the same small stretch of the Thames...?!

Well, it turns out our jokes had substance. Today, Dave Bradnum et al. located a very wintry-looking Bonaparte's just across the river at Barking Bay - the original bird! This meant that, quite sensationally, the more advanced individual we had located at the outfall on Saturday morning was indeed a second bird! In hindsight, it seemed highly unlikely that a bird would be able to moult so rapidly but, as we're talking Nearctic vagrants in East London, the one-bird theory still seemed more realistic at the time. When reviewing photographs, the bird also displayed different tail (possessing moulted central tail feathers) and tertial patterns in addition to the hood.

In other news, an adult Dark-bellied Brent Goose was also seen feeding off the outflow, and there was also a Little Egret and a 2cy Yellow-legged Gull.

Adult Dark-bellied Brent floating around on the Thames
So, two London Bonaparte's for Rich in a week, with the added bonus that it also finds its way on to my self-found list to boot... happy days. More photographs and details on the birds can be found on Rich's blog.

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