Welsh Journals

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DIVERS (GENUS GAVIA) IN WALES H. DICKINSON AND R. J. HOWELLS Divers make striking first impressions on the observer because of their distinctive streamlined appearance, massive bills, and effortless diving. Even on crowded waters their aloofness from other water birds makes them obtrusive. At close quarters the vivid red eyes, found in adults of all species, attract attention. Three species of diver, the Black-throated (Gavia arctica), Great Northern (Gavia immer), and Red-throated (Gavia stellata), are winter visitors to the coastal waters of Wales, but inland occurrences are rare. The open-water habitat and winter weather conditions seldom allow the observer to obtain good views of the diagnostic recognition features this often makes differentiation between Black-throated and Great Northern particularly difficult. The Red-throated, with its characteristic upturned bill and markedly speckled upper plumage, is the most common and is usually easy to recognize. The Black-throated and Great Northern are superficially similar, and distant views are liable to be mis- leading unless some size comparison with another species is possible. At short range the large size and massive bill of the Great Northern leads to immediate recognition. In accepting records of the Black- throated, which is a rare bird in Wales, we have tried to ensure that adequate size comparison or unusually good views were ob- tained, but this has not been possible in all instances. For this paper we have paid particular attention to the period 1950 to 1960, and our main purpose is to establish the relative numbers of the three species. A fourth diver, the White-billed Northern Diver (Gavia adamsii), has been reported from North Wales but the records have not been accepted. STATUS IN THE WELSH COUNTIES The distribution of diver records is given for each county, in order from north to south. In assessing the records, we have recognized that the distribution of competent observers on the coasts of Wales is very uneven. Flintshire Divers are seen every winter from both the Welsh and English sides of the Dee Estuary. Almost all are seen off the Hilbre Islands, where much watching is done, but a few penetrate higher up the estuary. Most of the records refer to the Red-throated, which is usually present from late August to April groups up to 100 strong have been seen sheltering after mid-winter gales. The Black-throated