Waders and Common Gulls

Contributed by John Sanders.

Black-tailed Godwit

There has been much talk in the national news about the early return of some of our autumn migrants and winter visitors, Black-tailed Godwits in particular. The theory goes that the summer weather has been so wet and cold that nesting attempts have failed, and birds have abandoned their breeding grounds to start their autumn migrations earlier than usual. This may be so, but the unseasonal weather in Britain has been blamed on the jet stream passing directly over the country. It is difficult to understand how this relatively narrow band of fast moving air can have affected the weather over the whole of Northern Europe. It is to be hoped that counts of juvenile birds will be made in the autumn, in order to discover just how unsuccessful the breeding season has been.

Common Gull PU93

I have been monitoring the Common Gull roost on the estuary at Purton, just south of the New Grounds at Slimbridge, for several years now. It is one of the few places in the County where I can check the birds for colour rings. When they are feeding and loafing on pasture the grass obscures the rings, and when they are following the plough they move so quickly that I cannot keep up with them. Even on the estuary it can be difficult, the birds are often too far away to read the codes on the rings. It requires a calm and sunny evening to have any chance of success.

I made my first visit to the estuary on 11 July, and saw just the odd one or two first-summer Common Gulls. They were obviously non-breeding birds, and had probably spent the whole summer on the river. However, on 19th there were already 450 in the roost. This is not a particularly early date, the birds normally start arriving after the middle of the month. Most were adults, with a few first-summers. It is usual for the juveniles to appear several weeks later. They were resting on a sand bar, a long way out, and as I panned my telescope through the flock I could see two white colour rings, but could not read them. By a stroke of good fortune, the incoming tide pushed the birds much closer to the river bank, and I quickly read the first ring, JP43. Any four digit code starting with the letter ‘J’ has to be from Norway, and sure enough this bird had been ringed as a nestling near Trondheim in 2004. It has been a regular in the Purton roost, gulls are great creatures of habit. The second ring was not so easy, it was old and worn, but at my third attempt I obtained a clear view, PU93. My heart missed a beat, could this really be. I checked again and, sure enough, there was no doubt. I first saw this bird in 1997, and it was old then, but my last sighting had been in 2009, so I had presumed that it had died. It was metal ringed at the Matsalu Nature Reserve in Estonia as a nestling in 1981, and then trapped as a female on the nest at the same place in 1987, when colour rings were added. It has returned to the reserve to nest each year since, and the colour rings have been changed twice more, as the original ones have become worn. This summer it laid three eggs, but the nest site became flooded in a storm on 12 May. Although the nest was rebuilt at a higher level, and eggs transferred, they were already chilled, and did not hatch. I received an interesting e-mail from the ringer, Kalev Rattiste, and he told me that there were further storms on 2 and 17 June. He said that PU93, at 31 years, is the oldest bird in the colony, and explained how she had failed in her breeding attempt, which would explain her prompt return to the Severn roost. So perhaps there is some truth in the theory that bad weather has caused the early return of many migrants. But then Kalev went on to say that he had ringed ‘only’ 1,356 nestlings this year, compared with 1,490 in 2011, so maybe it was not such an unsuccessful breeding season after all. We shall have to wait and see, but, what is certain, is that PU93 is the oldest colour ringed gull I have ever seen in nineteen years of recording.

Skip to content