17 FEBRUARY 1950, Page 14

Island Birds The Isle of May in the Firth of

.Forth is earning very high dividends as a bird observatory. Some months ago a visitor sent me a realty marvellous account of the rarities seen there during his short visit. It was, however, not so much these—a scarlet grosbeak for example—that interested me as the utterly unexpected fact that the island one day was thronged with greater spotted woodpeckers. The sanctuaries are now well equipped. Fair Isle has a hostel for visitors, and the business of observing seems likely to increase the population of this little treeless

island. The cages are so efficient that it has been found possible to catch and ring over 1,500 birds of 63 species. Rings so light that they do not incommode even small warblers are now manufactured ; and since the whole subject is international, we begin to get a very accurate plan of migration. , The North Sea, as Gadke proved years ago in Heligoland, is a marvellously frequented route, and the north-western side is probably the richest.