THE TUBE-NOSES 193 



their burrows at night and stretch and exercise for an hour or two, and 

 then return to the safety of the burrow. So does the young mutton- 

 bird, Pterodroma macroptera, which emerges from the burrows after 

 dark and ambles "about in an aimless fashion over tree-stumps and 

 other obstacles. They often return again to the burrow before daylight, 

 but sometimes take wing." (Falla, 1934). Those shearwaters which 

 are born in burrows in the centre of islands where predators are 

 numerous (as at Skokholm) may not reach the sea in one night. 

 If the weather be calm, the young bird is quite unable to rise off level 

 ground, and can only flutter down inclines. Unless it can find shelter 

 before dawn, therefore, it will probably be killed by gull or hawk. 

 But on other large islands, where there are no predators, the fledgeling 

 journeys safely by easy stages to the sea. Where shearwaters breed 

 in holes on steep cliffs, as in the Faeroes and Iceland, the take-off" is 

 only a matter of fluttering downwards, and the young bird, once 

 airborne in a good breeze, flies well by instinct. Normally, however, 

 the young shearwater flutters to the sea and makes its way into the 

 ocean by vigorous swimming. When attacked at sea by a predator it 

 dives deep, swimming for a long distance under water. It may be 

 aided on its first flight by autumn breezes ruffling the sea and thus 

 assisting it to take off'. Yet numbers of young petrels, shearwaters and 

 other newly fledged sea-birds get caught inshore in severe equinoctial 

 gales and are drowned in the breakers or carried far inland. The 

 westerly gales regularly experienced off' the west coast of the British 

 Isles in the autumn result in such a crop of inland records of Manx 

 shearwaters and storm-petrels that the late T. A. Coward erroneously 

 inferred that there was a regular migration overland. A study of 

 meteorological records, however, has proved that these occurrences 

 are always preceded by severe westerly gales. 



It is difficult to see how the chicks of some of the smaller petrels, 

 nesting deep among boulders and cliff" debris, can find space in which 

 to exercise and strengthen their wings before going to sea. It is remark- 

 able that the storm-petrel at this stage, with tufts of down still adhering 

 to its plumage, when taken from a rock crevice and dropped towards 

 the sea, avoids the water and will fly — though it has apparently never 

 fully stretched its wings before — making for the horizon low over the 

 sea. As long as the observer can watch it, it continues on the wing. 

 Well may we wonder at the astonishing vitality of these frail looking 

 petrels — storm-. Leach's, Wilson's, Bulwer's and frigate-petrels. On 

 land they are much more nimble than the heavier shearwaters. 



