Moult Adaptation in Relation to Long-Distance Migration

Marshall and Serventy 1 have recently directed attention to moult adaptation in the short-tailed petrel, Puffinus tenuirostris , of Tasmanian waters. In this species post-nuptial head and body moult takes place in the breeding quarters while moult of tail- and wing-feathers is postponed until the bird has arrived at its northern non-breeding quarters. From this the authors decide that “from the … data there emerges clear evidence of the evolution of a moult adaptation related to the migratory requirements of species that undergo a long post-nuptial migratory movement”. That moult adaptation in relation to long-distance migration need not be a general phenomenon, and probably has only taken place in certain families of birds, is indicated by the following observations on two species of long distance passerine migrants. In April 1953 a large number of swallows, chiefly consisting of the European swallow, Hirundo rustica , and the European house martin, Delichon urbica , perished in the neighbourhood of Cape Town, due to a short spell of adverse weather conditions. Of the thirty-five H. rustica examined, 99.1 per cent showed moulting flight-feathers, 65.7 per cent had moulting tail-feathers and 8.6 per cent had moulting body- and head-feathers. Of fifty-two D. urbica , 40.4 per cent had moulting wing-feathers, 75 per cent moulting tail-feathers and 94.2 per cent moulting body- and head-feathers 2 .