Tracing Gulls with Coloured Rings
Have you sighted any Black-headed or Common Gulls with coloured leg rings? A ringing study of Common Gulls and Black-headed Gulls began on Lough Mask, Co Mayo, last year, co-ordinated by the National Parks & Wildlife Service and supervised by Chris Benson, a British Trust for Ornithology (BTO) ringer.
The aims of the study are to investigate longevity, dispersal patterns, site fidelity and survival rates in these gulls, and also to monitor population trends. It is hoped to continue the ringing scheme for at least five years.
Lough Mask is a candidate Special Protection Area for wild birds under the EU Birds Directive. Although neither of the two gull species is listed under Annex 1 of the directive, both are amber-listed as species of conservation concern due to their unfavourable conservation status in Europe and because their national breeding populations in Ireland have declined by 25-50% in the last 25 years. Lough Mask holds a significant percentage of the breeding population of both species.
Progress so far
In 2006 and 2007, pulli (unfledged chicks) were ringed at two separate colonies on Lough Mask: Rams Island (Common Gulls) and an islet off Aghinish (Black-headed Gulls). All ringed pulli were fitted with a yellow plastic Darvic ring engraved with a four-digit code. The codes, allocated by the BTO, make it possible to identify each bird in the field individually.
The yellow coded Darvic rings were fitted on left legs and a corresponding BTO metal ring fitted on right legs.
A total of 387 Black-headed Gulls and 82 Common Gulls were ringed in May-July 2006, while 413 Black-headed and 108 Common Gulls were ringed in June 2007.
To date, there have been re-sightings of 27 Black-headed Gulls and 17 Common Gulls. These birds have turned up in coastal areas from Sligo to Waterford, though the majority of resightings have been in and around Galway city, some 40-45km from the ringing sites.
This dispersal pattern was also noted in Tony Whilde’s gull-ringing studies on Lough Corrib from the 1970s to the 1990s, and previous studies have shown that both Black-headed Gull and Common Gull first-year birds often winter at harbours and estuaries.
Re-sightings are, however, influenced by recorder activity; clearly, the more birdwatchers who are aware of the colour-ringed gulls, the more records will be received from around the country.
Both species are known to be faithful to their breeding colonies and do not mature until their second or third year. No first-year birds were noted at either breeding site. Therefore, it will be at least 2008 before colour-ringed birds return to Lough Mask or appear at other breeding colonies.
It is hoped that the present study will address the hypothesis that breeding Black-headed Gulls on Lough Mask are part of a larger, interchangeable ‘colony’ or a population that encompasses breeding birds on nearby Lough Carra.
For more details, contact:
Eoin McGreal
National Parks and Wildlife Service
Aghinish, Ballinrobe, Co Mayo
Tel: 094 95 42775
E-mail: eoin.mcgreal@environ.ie