Madam, - John Sweeney's comments on breeding birds and global warming, quoted by Sean McConnell in your edition of May 5th, have almost certainly some validity. But only three of the eight species he mentions - little egret, Mediterranean gull and to some extent, reed warbler, (a newcomer even if not traditionally confined to Mediterranean lands) - bear this out.
Of the other five mentioned, two, the blackcap and whitethroat, have been breeding in Ireland for over 100 years, while the pied flycatcher, bearded tit - and, incidentally, lesser whitethroat, a different species from "whitethroat" - are recorded as having bred in Ireland for the first time only since 1970, have not so far estbalished any regular breeding populations, and in any case are widespread European rather than Mediterranean species.
The goosander, which now appears to be permanently established in very small numbers, is a northerly species which has colonised Ireland in the course of spreading southwards; and another northerly species not mentioned in the report, the great skua, has also recently spread southwards to colonise Ireland in small numbers, so the situation definitely appears to be more complex than Dr Sweeney's remarks indicate.
However, in seeking to derive evidence of global warming from disappearing northerly species, it may be noted that the red-necked pharlarope declined from up to 50 pairs early in the 20th century to none known for certain since the 1980s, while during the same period breeding golden plover have vanished from all over their former haunts south of a line from Galway to Belfast. Most 20th-century extinctions, however, appear to have been more due to human agency than anything else, e.g. persecution (two eagle species), drainage of swampy lakes (black-necked grebe) and modernisation of agriculture (corn bunting, plus the near extermination of the corncrake).
In order to monitor the breeding success rates of rare and seriously declining bird species so as to afford them the best protection measures possible, the Irish Rare Breeding Birds Panel has been set up recently. This panel collects rare bird breeding records, employing strict confidentiality where necessary. It is hoped thus to support and conserve Ireland's naturally occurring heritage of wild birdlife more effectively. - Yours, etc.,
J. PAUL HILLIS, Honorary Secretary, Irish Rare Breeding Birds Panel, 61 Knocknashee, Dublin 14.