It’s not really too surprising that the fine weather this summer is currently helping the sea birds to do well at the Oysterbeds. Since my last update yet more Common Tern young have hatched and, just in the last couple of days or so, several new incoming pairs have set up territory and have begun nesting. These are perhaps likely to be pairs that have failed on there first breeding attempt on the main Langstone Harbour islands. In fact, I strongly suspect that, as well as the attraction of the new shingle on South Island this year, the increase in the numbers of breeding Common Terns at the Oysterbeds this summer is also been a function of their higher breeding success here. Although second attempts are often not as successful as first attempts some have gone on to raise young on the reserve late in the season here during recent years. My guess is that ALL of the successful breeders quickly return in the next spring to the site they were last successful on, which helps to attract in all the others (at the Oysterbeds this has all been helped by the improved habitat, of course!). Like Little Terns, the provision of viable breeding sites for Common Terns is now important in Langstone Harbour, bearing in mind that the harbour, including the Oysterbeds, support over 1% of the UK breeding population of this species.
OK, so you’re bored with the stats.... Moving on swiftly, some of the tern chicks are now a fortnight old. During next week some will be taking their virgin flights. In the meantime they are jostling for position on the islands. South Island is positively bristling with hungry chicks! Inevitably there are a few squabbles and fracases, mostly minor but sometimes more violent. Most days I spend at least some time watching the terns closely and have witnessed quite a few attacks on chicks from adults. Most of them appear to involve neighbouring adults and chicks, the latter getting too close and wandering into a neighbours territory. But it does seem that a few Common Terns are much more prone to unprovoked attacks on chicks, and I have seen adults attacking small home-alone chicks still at the nest site while the parents are away. It’s not always entirely clear if these more aggressive attacks are made by adults with their own chicks or not.
Those who have visited the reserve recently (wot, you mean you haven’t visited yet?!) will have seen the strange wooden structures on the South Island. As noted in the previous post they are “chick shelters” and specially placed! I have been really pleased to see that many of the chicks are using them for a variety of reasons. Mostly they use them for shade during the heat of the day, or as a wind break. Others are using them as a hiding place from unwanted attention from neighbouring adults. A slightly comical video clip can be seen below...
Predation of chicks from incoming aerial predators is a real risk but so far it has been largely absent. I have chosen my words carefully, as this evening two tern chicks were taken in quick succession by a hungry adult male Mediterranean Gull. Maybe he is the same bird which predated chicks for a couple of weeks last summer. After his chick feast he flew to South Binness Island in the main Langstone Harbour where some 400 pairs of Mediterranean Gulls are nesting. The tern chicks need to grow up fast! Earlier this month I had seen a Mediterranean Gull take eggs from the colony, on each occasion apparently stray eggs from the bare shingle (of which there are a scattering, if you look really closely through a telescope). On Saturday I watched an visiting adult Lesser Black-backed Gull take two Black-headed Gull chicks from the colony.
The young Black-headed Gulls have grown fast, and the first one has already fledged. The following images show how developed some of the larger fledglings are (click on each one to enlarge them). The one in the first image is looking out over the lagoon waters just prior to taking its first fluttery flight on Sunday.
Many more young will have fledged by this time next week. But, as there are still a few birds still on eggs, and a few very small chicks, the fledging season will be protracted. Already more and more broods are moving away from the lagoon islands and ending up around the edge of the lagoon or in the sheltered bay just to the south.
For a complete picture story of the progress of the various species on the Oysterbeds this summer please visit Peter Drury's excellent photo gallery.
Just a little bit of bad news for the Oystercatchers. One of the three pairs nesting on the North Island has failed within 48 hours of successfully hatching one chick. Exact cause unknown, but a similar thing happened to this pair last year. There are two pairs still on eggs. The pair on South Island still have their one youngster, which has already got into the high tide roosting habit of its parents (rather than trying to snuggle under the wings or body of mum!).
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