350 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 9 



There is much more that might be said of that interesting and 

 unusual individual the shearwater, but I must pass on to a brief 

 mention of our work with individuals of other species of sea birds — 

 the storm petrel, Hydrohates pelagicus (L.), for instance, which 

 breeds in numbers in the rock crevices and old farm walls of Skok- 

 holm. In a similar study (8) of individuals it has shown a life 

 history not unlike that of its cousin the shearwater: nocturnal on 

 land — a long incubation period of 38 to 40 days — and an average 

 fledging period of 61 days. The chick is deserted in the end, and 

 flies off to the sea on its own when sufficiently thinned down from 

 its over-fat nestling stage. The storm petrel is more nervous and 

 difficult to observe than many sea birds, but we have individuals 

 on our books that have been breeding in the same crevice on the 

 island for 4 vears. 



So, too, with the puffin, Fratercula arctica grdhm (Brehm). Our 

 ringing study of this bird enabled us tO' discover several new facts 

 (9) : an incubation period of 40 days and fledging period of 49 

 days; also that this bird, too, is deserted by its parents, although 

 other members of the auk family to which it belongs, the razorbill 

 and the guillemot, feed and accompany their chicks at sea when these 

 leave the rocks where they were hatched. The puffin follows the 

 petrel family in deserting its single chick, but this desertion, as with 

 the petrel family, is a wise provision. The guillemot and razorbill 

 chicks, hatched on the precipitous ledges of the cliffs, can and do eas- 

 ily jump or flutter down to the sea and their waiting parents. Wlien 

 they take off like this they are fully feathered but only half-grown, 

 and are so small and light that even if they hit the rocks a hundred 

 feet below on rare occasions, they generally bounce off unhurt, and 

 scramble off to the safety of the sea. They leave in broad daylight, 

 when they may best see their parents on the sea below. But the 

 puffin is often reared in burrows some distance from the edge of the 

 cliffs, and so has a long walk to get to that edge, and during that walk 

 it would be exposed to the attacks of gulls and hawks. Moreover, it 

 is full-grown and very fat when it is deserted by its parents. It 

 certainly needs a fast of a week or so to make it light enough to take 

 off without fear of crashing on the rocks below the cliffs. So the 

 young puffin solves these problems (the problem of its excessive 

 weight, and the problem of the predatory gull) by starving for some 

 days before selecting a dark night for its lonely and unseen, but 

 momentous, stroll to the cliff edge, where it takes the plunge to that 

 friendly element, the sea. 



One of the most attractive birds to study has been the razorbill, 

 Alca torda (L.). It is a handsome looking bird and nests in the 

 pleasant environment of the rocky slopes of the island shore, where 



