20 July 2013 Oysterbed update from Chris Cockburn

Hello folks

It’s beginning to get less crowded out on the two lagoon islands with the departure of many black-headed gull families (productivity seems to be heading for c1.65 young per pair).

Despite the lower bird numbers, noise levels are still quite high especially when the black-headed gulls are shouting at their squeaking youngsters as they fly in and out of the lagoon.

The five Mediterranean gull nesters will most likely have a final productivity rate of 1 young per pair and it should not be too many days before they leave.

Sandwich terns in moult are now a regular sight; today there were 30+ and it is noteworthy that they are clustered around the Mediterranean gulls on the easternmost curved island. It is likely that the strong black hood/white neck contrast attracts Sandwich terns to Med gulls (and vice versa as often noted on South Binness Island in previous years). It is also interesting that the Sandwich terns started using the Oysterbeds on the day after a sailboarder was seen enjoying a stroll along the S Binness vegetated ridge in areas often favoured by Sandwich terns.

It looks as if the breeding season for common terns will continue for many weeks. There are many youngsters able to fly, there are chicks from newly hatched to almost three weeks old and there is a significant number of adults that are apparently on eggs. The main pattern seems to be that the common terns have two eggs that hatch with only one chick surviving more than a few days.  The surviving singletons all seem to be doing well so it is likely that there is a food problem with only enough prey items for one chick (but given the lateness of the breeding attempts, another factor might be that the terns have not reached the best breeding condition).



Chris C

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