Bird Ringing
SEABIRD RINGING Since systematic ringing work began on Treshnish in 1971, more than 34,500 birds have been ringed, generating large numbers of retraps and recovery records over a substantial time span. All computerised ringing records are submitted to the British Trust for Ornithology’s National Ringing database, making the information available for analysis both on a local basis and as a contribution to the national picture. This has allowed a picture to be built up of the movements and life history of our various seabird species, and interactions with other seabird colonies in the West of Scotland. Of key importance is the contribution made by our study to the numbers of breeding adult auks ringed in Britain, notably Guillemots and Razorbills, which fairly few other ringing teams are able to capture. Many pulli of these species are ringed elsewhere, and these are valuable in terms of exact known age, but sampling a population of known adults of breeding age is very useful as all these have survived the heavy juvenile mortality and may be expected to survive a number of breeding seasons. Also important is our large-scale ringing of breeding Storm Petrels, which is generating data for integration with tape playback population surveys. We are currently carrying out RAS studies of Storm Petrel and Shag (noted elsewhere), and ringing pulli of various species in specific areas of the main island. General ringing using a variety of capture methods has provided a number of less abundant species, including Corncrake, Bonxie (Great Skua), Common Gull and Twite. Present aims in relation to ringing activity are: · Continue main thrust of ringing work, ensuring adequate annual samples of auks, Storm Petrel & Shag; · Progress analysis of retraps and controls of Harp Rock auks; · Integrate Storm Petrel ringing activity with population surveys; and, · Develop further species studies e.g. Puffin, Kittiwake. Our data from Lunga together with two other independent Storm Petrel ringing programmes (Priest Island, Highland Region and Banneg Island, Brittany) have been made available to RSPB to examine the influence of sea surface temperature and chlorophyll a concentration on adult survival.