17-June-13
After I saw you Allan, both birds returned and spent some long-time perched on one of the small rafts in front of the Walton viewing screens; also flying around excitedly calling and one presented a fish to the other. One of these adults is wearing a BTO aluminium ring on its right leg. All very interesting!
This could perhaps be related to the Lodmoor common tern colony that desorted en masse last week. Toby Branston of RSPB has said:
By now many local people would have noticed that the common tern colony from our Lodmoor salt marsh island have disappeared. There appears to have been a mass desertion event overnight on 13 -14th June which left over 62 nests with eggs abandoned. This event has been much discussed with the cause open to some debate. Food resource could be a factor with disturbance to the abundance of their main prey item, sand eels by the cold spring. There is some evidence for this as birds were travelling further into Lyme Bay to fish rather than Weymouth Bay just over the sea wall and the link with low mackerel numbers. Canada geese have, as has been pointed out, increased in recent years on the saltmarsh and disturbance from them may have occurred. Disturbance from mammalian predation (fox, mink or stoat) is thought not to be a likely cause and we have found no evidence of mink presence. Indeed, a combination of factors might have caused a build up of stress to an unacceptable level for the birds which resulted in the drastic action witnessed. Sadly, it is not an uncommon occurrence and the common terns locally have deserted en-mass from the Fleet / Chesil in relatively recent years and formed subsequent new nesting grounds nearby, our islands being one of these some 10 or more years ago. We are hopeful that they may return to the islands next year but in the meantime we shall be looking further into the likely causes.
Probably unrelated to the other sightings, but an 'odd' bird was present at Cheddar on Sunday afternoon. It was notable in that it had a completely black bill, a white forehead and a dusky carpal bar. It was obviously not a juvenile on plumage and time of year. It did not appear to be an adult on time of year and bare part colour, so the best I could come up with is a second summer bird. Does anyone have experience of this plumage or other comment?
First-summer, probably (second calendar year). Most birds of this age don't bother to migrate north, but a few do each year, and odd ones occasionally pop up. The description sounds spot-on for a first-summer Common.
First-summer Arctics are rarer, but still also occur - I had one such bird on a Burnham seawatch in May. They have much less by way of a carpal bar and typical Arctic-type primaries.
Roger, I believe this is the plumage previously known as 'Portlandica' which was once thought to be another species. This term applies to Arctic Terns certainly, but I think also to Common Terns as it relates to the age of the bird. Anyway it's worth Googling 'Portlandica' for some interesting history and observations on this plumage.
There was a pair at Ham wall this evening, they were ranging over the whole area but favouring Walton Marsh. I last saw them at about 2015hrs when they headed off in the direction of Shapwick.
3 Common Terns on the east pool on Walton RSPB reserve midday today .
2 Green S'Pipers from 2nd viewing point (Ham Wall) There was also a single one on the scrape on Shapwick yesterday and half a dozen BRIEF views of Little Bittern in 4 hrs from the L.B. view point, in yet again extreme heat!
