Another London rarity! (19th May 2012).

Dave and I started the morning at the Chingford reservoirs, where we carry out a monthly count of the waterbirds present as part of the Wetland Bird Survey (WeBS), which helps to assess national populations of wetland species.

It was a glorious sunny day – but this is the type of weather conditions that aren’t likely to bring the more interesting species that we might hope for to the reservoir. The good weather meant that visibility was good, and the water was calm and flat, but poorer conditions, including rain, are more likely to make passage birds like Black Terns and Little Gulls drop in as they pass over at this time of year.

We weren’t at all surprised to find that bird-wise the reservoirs were very quite. With most wintering birds having left, and few passage species present, we found that the count didn’t take too long at all. Neither reservoir has any islands, and both are concrete rimmed with bare, sheep grazed banks, so they aren’t attractive to most breeding species. A few pairs of Canada Geese do breed each year though, and a pair of Shelduck were present on the King George V Reservoir, with a new brood of 14 ducklings. Also of interest were a couple of pairs of Linnets on nearby rough ground, a few passage Common Sandpipers, Common Blue Damselflies and some flowers that had escaped being eaten by the sheep.

During the morning we had received news of a Bonaparte’s Gull, the North American counterpart of the Black-headed Gull, which had been found on the River Thames not too far away (the second record in the London Area, with the only previous one in 1983).

It proved elusive during the middle part of the day, after having been seen at Crossness and Barking Bay in the early and mid morning,  but with three other observers we found it again in Barking Bay as the tide ebbed late in the afternoon.

It was a 1^st summer individual, although it had yet to start showing any sign of a dark hood. In size and appearance it was something like a cross between a Black-headed Gull and a Little Gull, superficially more like a Black-headed Gull, but with a black bill, pink legs, an indistinct grey wash on the nape, and a different pattern on the wings – most noticeably the pale underside to the primaries. It’s behaviour and flight action was more reminiscent of Little Gull, which meant that it could be fairly easy to pick out from the Black-headed Gulls at times – not always though!

The above, rather poor 'phone-scoped' photo (taken through a telescope with my mobile phone) does show the Bonapartes Gull, rather than the more numerous Black-headed Gull (honest!). Better photos were taken by other observers, closer to the bird when it had been seen in the morning, and over the following days. Remarkably a second Bonaparte’s Gull later joined it!

Mainly Gulls (19th March 2012).

Yet another Iceland Gull had been seen at Rainham on Friday and Saturday (16th & 17th), but this one was a bit different, and was something that I was keen to try and see - a Kumlien's Gull. Kumlien's Gulls are usually treated as a race of Iceland Gull, breeding slightly further west in north-eastern parts of North America than the nominate race (or 'typical' Iceland Gulls) which breed in Greenland, but are now often considered to be hybrids between Iceland Gulls and Thayer's Gulls.

Whatever they are, it didn't really matter because the bird didn't show at all today! There had also been no sign on Sunday, but I hadn't really expected there to have been, and didn't visit then, because the refuse tip isn't operational on Sundays so there are fewer gulls visiting.

There were still interesting birds to see, with at least two 2nd winter Iceland Gulls present, and seen frequently over the tip, bathing in the River Thames, or just loafing about with the hundreds of Herring Gulls, Lesser Black-backed Gulls, Great Black-backed Gulls, Common Gulls, and Black-headed Gulls.

Careful checking through the gulls here usually produces Yellow-legged Gulls, of which possibly about a dozen were present (all immatures)...

...and with a little bit of time and/or luck it is also usually possible to find Caspian Gulls - I saw at least two 1st winters, and one 2nd winter. Caspian Gulls (and Yellow-legged Gulls) can be easy to overlook, but once you know what you are looking for some Caspian Gulls at least can be picked out quite easily by their shape and stance. One of the 1st winter Caspian Gulls is on the right in the photos below.

Large gatherings of gulls are also worth checking for individuals that have been colour ringed. These rings are designed to be possible to read in the field with a telescope (or binoculars if you are close enough) and by reporting the code and ring colour via the BTO you can help to further the study of gull movements (the same is true for other types of bird). A Lesser Black-backed Gull that I saw while on holiday in the Gambia a month ago turned out to have been ringed on the Suffolk coast!

I managed to read the rings on four gulls, including the one below. There is a good chance that they were all ringed by the London Gull Group on Rainham tip and haven't moved anywhere though:

When I pulled my attention away from the gulls, other birds along the Thames foreshore included a pair of Oystercatchers, a Scandinavian Rock Pipit, and two Water Pipits. One of the Water Pipits was a very smart individual in full breeding plumage, with a pink breast and pale grey head. That one didn't allow itself to be photographed though, and I had to make do with a poor shot of this moulting individual: