Roseate tern  (Sterna dougallii)

The roseate tern was first identified in 1812 by Dr MacDougall of Glasgow, hence the specific name dougallii (2). Males and females are similar in appearance; during the breeding season they have a black forehead, crown and nape (2) and pale plumage with a rosy tinge to the breast, (3) which gives the species its common name (4). The grey tail is deeply forked with white long outer feathers called 'streamers' (3). In winter the forehead becomes white (3). A particularly vocal species on the breeding grounds, calls of the roseate tern include a 'chew-ik' and a 'kraak' when alarmed (2).

The roseate tern is widespread around the world, but its range is highly fragmented (5). In Britain, it breeds in Northumberland, the Firth of Forth and Anglesey and migrates to West Africa, especially Ghana for the winter (2).

In Britain the roseate tern forms colonies with common and Arctic terns, usually on offshore islands. Nest sites are sheltered by overhanging rock or vegetation (2).

In Britain and Ireland, the diet consists mainly of small fish, especially sand eels (5), which are caught by plunge-diving (2) or are stolen from other tern species (5).The roseate tern arrives back in Britain later than other terns and soon starts to lay eggs (5). One brood containing between 1 and 3 pale eggs is produced between the end of May and early June, but a replacement brood can be produced if this clutch is lost. Juveniles reach maturity at 3 years of age (2).

The roseate tern is one of the rarest breeding seabirds in the UK; in 1996 only 64 pairs were recorded over 5 main sites. The UK population has decreased from 1000 pairs in 1969 to 210 pairs in 1989, but this is largely due to the relocation of many birds to a colony in the Republic of Ireland (6). Threats to this species include predation by foxes, brown rats and peregrines. It is likely that predation prevents the species from establishing colonies on the mainland, where predation pressures would be greater (2). Human disturbance and egg collecting may have taken a toll on the species, but this has largely been prevented in the UK by wardening schemes. Factors operating in the wintering range or during migration, such as trapping and a reduction in roost sites, will have affected adult and juvenile mortality (2). At some UK sites, flooding of the nests has been a problem and competition for nesting sites with other species of tern and even gulls may occur (6).

All roseate tern colonies in the UK are located within reserves and have been designated as Special Protection Areas (SPAs), a European designation (2). Artificial nesting boxes have been provided at some sites. It is hoped that this will reduce the incidence of predation and disturbance. Between 1985 and 1994 the RSPB and Birdlife International funded an education programme in Ghana, which aimed to reduce trapping of the roseate tern during winter. The roseate tern is a UK Biodiversity Action Plan priority species. The Species Action Plan aims to increase the UK population to 200 pairs by 2008 (6).

For more on British birds see the RSPB website:
http://www.rspb.org.uk

Information authenticated by the RSPB:
http://www.rspb.org.uk/