A record day for Caspian Gulls in London

Dante S scored hefty totals of 12 and 17 Caspian Gulls at Rainham Tip on Tuesday and Wednesday respectively – both exceptionally high counts for this site, with the latter in fact comfortably beating the previous record single-site count (of 13) from the London area.

With Thursday morning free, I met up with Dante and we headed over to Rainham for 8 am. It was a grey morning with bouts of drizzle and a strong southerly wind that was gusting up to gale force at times for a couple of hours around lunchtime – not exactly optimal for viewing along the exposed riverside footpath towards Coldharbour Point. Nonetheless the Casps soon started flowing with a flyover first-winter quickly followed by three more on the river itself, including a particularly fine bird with moulted coverts and tertials on the rocks by Coldharbour Point lighthouse, pictured below.

1cy Caspian Gull, Coldharbour Point, Rainham, 29 November 2018. One of 13+ first-winters seen on the day.

The setup is currently pretty good at Rainham. Veolia are currently actively tipping on the river side of the landfill site, which means the birds are more inclined to wash and loaf on the river. While the tip face is a tad distant to view from the riverside footpath, the views are generally pretty good when they come down to the river itself, usually just to the east of Coldharbour Point. At low tide, there are usually a few birds along the foreshore as far as Aveley Bay, with a roost of up to a few hundred birds just west of the lighthouse. Add the fact that there is plenty of turnover as birds commute between the tip and river and it's reasonable to assume that you'll be getting views of a good proportion of the birds present if you're willing to give it long enough. It's worth pointing out that numbers are by far best on weekdays, with Saturday mornings much quieter and Sunday more or a less a write off.

Our Caspian Gull total steadily rose throughout the morning and we were in double figures by lunchtime, despite the odd half-hour lull where few birds were using the river. In the afternoon were joined by Rainham stalwart Andy Tweed, with the three of us ensuring good coverage of the large numbers of birds commuting between the river and tip face as the afternoon wore on. I don't think we were missing any birds that came down on the river itself, but of course it's always difficult to gauge just how what percentage of the birds you've looked through – bear in mind that we were still seeing new Herring and Lesser Black-backed Gulls by the time we left (recognised by distinctive stains, plumage etc).

When Dante picked out a smart second-winter on the river a little after 3 pm, it signalled the end of a memorable session. Our final total of 19 individuals was very much conservative. We managed some sort of record shot of at least 12 of these birds, with detailed plumage and structural notes taken for the remainder. Some individuals were definitely seen more than one, while we also had sightings of birds which may (or may not) have been different that ultimately did not count towards the final total. The breakdown was as follows: 13+ first-winters, two second-winters, two third-winters (both birds seen on our trip the previous week), a fourth-winter and an adult. A few terrible phonescoped shots of some of the birds follow in a slideshow ...

I'm not sure what the British record single-site count is for Caspian Gull (there was a report of 23 from Rufforth, North Yorkshire, a few winters ago, but I'm not sure if this was ever verified), but surely 19 must one of the highest ever made? Answers on a postcard please.

As for Rainham ... well, this is something of a renaissance for a site that Dominic Mitchell has occasionally mourned as nigh on finished while talking gulls in the Birdwatch-BirdGuides office in recent months. In the three chastening days Dante spent on the riverside footpath, he notched up a minimum of 28 different Casps (again conservative, with the figure more likely at 30+), which suggests that a day count exceeding 20 is comfortably within the realms of possibility if the stars align. Perhaps there's life in the old dog yet – as long as birders keep chucking their food waste in the general household bins, there'll be at least some food going into landfill for the gulls!