Welsh Journals

GREY SEAL BEHAVIOUR A. L. JOHNSON In the autumn of 1966 I spent ten days in Orkney at the in- vitation of E. A. Smith of the Natural Environment Research Council assisting their party which was working on parasitology, behaviour, pup growth and population studies of the Grey Seal (Halichoerus grypus). F. Fraser Darling (1964) suggested, from his pre-war obser- vations on the west coast of Scotland, that the various grey seal colonies appeared to be segregated into separate clans, and that interbreeding between the various groups did not occur. More recent authors (Darling and Boyd, Hewer, Lockley and Matthews) have listed a considerable number of differences in the behaviour of the seals of the diverse colonies. It would seem a reasonable pre- liminary hypothesis that some of this difference in behaviour at the breeding time is due to the difference in breeding conditions, and this has been suggested by H. R. Hewer (1960). Most of the breeding in Orkney takes place on fairly small uninhabited islands some hundreds of yards in diameter, rising some tens of feet out of the water. Usually there is fairly easy access in places from the beach to the top of the island. On all the isiands used for breeding there were pups present on the beaches above high water mark. In addition to this, in a number of cases the seals were breeding well inland on the top of the island though there was usually some reduction in the breeding density away from the beaches and the gullies leading up from the beaches. On North Rona many of the cows breeding inland stay inshore with their pup for most if not for the whole period of suckling. In Orkney, possibly because the journey involved is usually less arduous than on North Rona, quite a number of the cows breeding inland visit the sea occasionally. Comparing Orkney in general with Pembroke- shire, however, it would appear that the cows in Orkney spend much more time ashore with the pup than is the case in South Wales, though there is a considerable difference in the amount of attention the individual cows devote to their pups the territorial bulls in Orkney also stay ashore for quite long periods. In Pembrokeshire, matings almost always take place in the surf or in the sea I saw several attempted matings and two successful matings in Orkney, in each case these took place on land. On the southern island of Orkney, South Ronaldsay, con- ditions are different, breeding takes place on small shingle beaches backed by steep cliffs and also in caves. The coast is subject to a moderate amount of disturbance by inshore fishermen, and a number of the beaches though fairly isolated can be reached from the land. These beaches are very similar to the breeding beaches used by the grey seals in Pembrokeshire and the pups are born in