Welsh Journals

The first eggs are laid soon after April 20th, three being the normal number. Incubation is for about 27 days and is carried out by both sexes. The chicks move out of the nest as soon as they dry after hatching and hide themselves close by. As they grow older they are able to move more freely, but they do not go far from the proximity of the nest unless disturbed. By about the eighth week they can fly and then are no longer dependent on their parents. For the rest of the season the juveniles congregate with the adults in large flocks at such favourite spots as the Spit or near the Basin. During late August there is a gradual dispersal away from the island. The young birds rarely return to Skomer until adult plumage is attained in their fourth year they probably commence breeding in the following season. The numbers of adults present by day in the autumn dwindles after September but many return each night to roost. FOOD Since the end of the 1939-45 war there has been a vast increase in the British fishing industry with accompanying large disposal of fish waste at sea, all favouring a larger gull population. At the same time there has been an increase in the number of rubbish dumps, sewage outlets, etc., all providing excellent feeding grounds for gulls. Skomer is some 1 miles from the fish docks at Milford Haven, which provide a regular feeding ground, whilst the island provides suitable nesting sites and, at the present time, an inexhaustible food supply from other breeding sea-birds and rabbits (Oryctolagus cuniculus). Even during the breeding season a number of gulls go each day to Milford Haven for food. Evidence of this may be obtained from commercial fish remains round some nests, par- ticularly on the Neck. It is interesting to note that Davis (1958) recorded that fish remains from commercial species were the most numerous food remains amongst the colony of some 90 pairs on nearby Midland Island. Each pair of gulls and indeed each individual would seem to have its own particular feeding habits (Conder, 1953). Evidence of this may best be obtained from a survey of food remains at nest sites at one fish remains will be pro- minent, at another Shearwater remains, at a third rabbit, and so on. The Manx Shearwater (Procellaria puffinus) and Puffin (Frater- cula arctica) provide the main bulk of food from the sea birds, but small numbers of Razorbills (Alca torda), Guillemots ( Uria aalge) and young Kittiwakes (Rissa tridactyla) are also taken. Few eggs are taken and there is no evidence of predation on the adults or young of either Lesser Black-backed or Herring Gull. The Great Black-backed Gull has several methods of hunting which vary according to which prey is sought. Shearwaters are mostly caught at dawn, before they can find a burrow or escape to the sea, though some are caught at night when they blunder into