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The Food of Grey-Faced Petrels (Pterodroma macroptera gouldi (Hutton)), with Special Reference to Diurnal Vertical Migration of their Prey

1973; Wiley; Volume: 42; Issue: 3 Linguagem: Inglês

10.2307/3130

1365-2656

M. J. Imber,

Cephalopods and Marine Biology

Although the ecology of several species of Procellariidae (petrels, shearwaters and fulmars) has been studied by many ornithologists, of the eleven genera only Fulmarus, Puffinus and Pachyptila have received much critical attention; Pterodroma, which comprises more species than any other genus in the family, has been little studied. This is because Pterodroma is an oceanic genus breeding in the tropics, sub-tropics and southern hemisphere in places difficult of access such as remote islands. In common with most pelagic birds the food and feeding habits of gadfly petrels (Pterodroma spp.) are known only vaguely (see Ashmole 1971). A number of authors have recorded food remains obtained from petrels they handled. Often stomachs were empty but for digestion-resisting fragments of cephalopod beaks and eye lenses, fish bones, crustacean exoskeleton or pieces of stone or pumice. This situation seems to result from rapid digestion combined with infrequent feeding. The following information applies to Pterodroma only; comparisons with some other genera are made in the discussion. Cephalopods have been reported in the diet of P. m. macroptera (Smith), P. m. gouldi (Hutton), P. cooki (Gray), P. leucoptera (Gould), P. neglecta (Schlegel), P. cahow (Nichols & Mowbray), P. lessoni (Garnot), P. solandri (Gould), P. brevirostris (Lesson), P. mollis (Gould) and P. phaeopygia (Salvin) (Sladden & Falla 1928; Oliver 1930, 1955; Falla 1934, 1937; Palmer 1962; Mougin 1969; Harris 1970; Serventy, Serventy & Warham 1971; Wingate 1972). Fish are eaten by P. inexpectata (Forster), P. phaeopygia, P. solandri and P. mollis (Kuroda 1955; Pocklington 1967; Harris 1970; Serventy et al. 1971). Crustacea are taken by P. macroptera gouldi, P. neglecta, P. phaeopygia, P. brevirostris and P. cahow (Sladden & Falla 1928; Oliver 1930; Larson 1967 per Harris 1970; Mougin 1969; Wingate 1972); those eaten by P. cahow include a small scarlet shrimp (Palmer 1962). Other pelagic organisms have been noted among food of P. macroptera gouldi and P. phaeopygia which took pteropods (Oliver 1930; Loomis 1918 per Harris 1970). But none of these workers was able to analyse the composition of the food or to identify food items to a lower level. Thus the food of gadfly petrels (and shearwaters, Puffinus spp.) was known only by generalizations until Ashmole & Ashmole (1967) examined the feeding ecology of Procellariidae, Phaethontidae (tropic-birds) and Sterninae (terns and noddies) on Christmas Island in the central Pacific Ocean. The petrels they studied were the phoenix petrel (Pterodroma alba (Gmelin)) and the Christmas Island shearwater (Puffinus nativitatis Streets). Detailed comparisons of their findings with mine are made in the discussion. In their analysis of samples from Pterodroma alba they identified several