After reading on Steve Hale’s Avon Birds Blog yesterday about an unidentified tern in Bristol Docks, Martyn Hall and I went to look for it this afternoon. We started from the western end and found it almost straight away, sat on a boat near the Harbour Master’s office. Mystery solved: it was a breeding-plumaged adult Common Tern (Sterna hirundo). It flew off before either of us could get a photo of it perched, and spent most of the next hour flying around, attempting to feed, although we didn’t see it catch anything. It ranged eastwards at least as far as the S.S. Great Britain, and west as far as the Cumberland Basin. I managed a few very ropey photos (my skills with my new bridge camera aren’t up to flight shots yet) but Martyn managed some much better shots, first on one of its fly-pasts, and later when it was feeding in the Basin. Here are some of them:
|Common Tern, 12 May 2013, Bristol Docks, Martyn Hall (www.martynhallphotography.com)|
Interestingly, it seems as though this could be the first confirmed record of Common Tern in Bristol, away from the Severn estuary and its environs: the M5 Avonmouth Bridge, where three were seen on 2 August 2009, seems to be the farthest that Common Terns had ventured into the city previously.
I checked the National Biodiversity Network database and there are no inland Bristol Common Terns among its 89 million records, and looked through past issues of Avon Bird Report from 1979 to 2011 and also drew a blank, although there are five records of birds which were either Common Terns or Arctic Terns (Sterna paradisaea); presumably they were seen too briefly or distantly to confirm which species. The 2012 report hasn’t yet been published, but I don’t recall any reports of Common Tern in the city last year. Before the 1980s, Sterna tern records were generally published as unidentified Common or Arctic Terns (as the two were thought to be too difficult to tell apart). The five previous records that I could find of unidentified Common or Arctic Terns in the inland part of the city are as follows: five southwest over Bishopston on 13 Sept 2010, four over Totterdown on 4 Apr 2004, four seen flying under the Clifton Suspension Bridge on 21 Sept 1990, three at Hotwells on 19 Sept 1982 and one in the City Docks on 1 Oct 1982. There are also several definite Common Tern records from the River Avon at Keynsham, Saltford and Bath.
In the estuary and at our local reservoirs, Common Terns are, of course, common migrants in both spring and autumn. None have yet been tempted to stay and breed. An attempt at creating a platform for terns to use as a nest site, at Chew Valley Lake back in the 1980s, unfortunately failed when one end of it sank, leading to it acquiring the nickname the “ski jump”. A little farther afield, there is an established population in the Cotswold Water Park, and single pairs have bred in recent years at Slimbridge and on the Somerset Levels.