THE BREEDING CYCLE OF THE SHORT‐TAILED SHEARWATER, PUFFINUS TENUIROSTRIS (TEMMINCK), IN RELATION TO TRANS‐EQUATORIAL MIGRATION AND ITS ENVIRONMENT

• Published in: Proceedings of the Zoological Society of London
• Main Authors: MARSHALL, A. J., SERVENTY, D. L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1956
• Subjects: Arctic; Burrows; Mutton; Pacific; Puffinus tenuirostris
• Online Access: http://dx.doi.org/10.1111/j.1096-3642.1956.tb00484.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1096-3642.1956.tb00484.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1096-3642.1956.tb00484.x; https://zslpublications.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1096-3642.1956.tb00484.x

SUMMARY The Short‐tailed Shearwater, Puffinus tenuirostris , migrates annually with remarkable constancy between its southern Australian breeding islands and the north Pacific and Arctic Oceans. The regularity of its southern landfall (in late September) and egg‐laying (during the period November 19 to 21 and the following twelve days) facilitates its commercial exploitation in the Tasmanian “mutton‐birding” industry. The species is highly exceptional in that it breeds in the warmer of the two regions between which it oscillates. It arrives in the breeding area and remains there during the period of surface swarming of the euphausian plankton on which it mainly feeds. Gametogenesis almost certainly begins in the northern hemisphere and this and the nuptial migrations are perhaps initiated by decreasing daylengths. The males possess bunched spermatozoa on arrival at the breeding islands. Individuals “home” to the same nesting site each year. Spermatogenesis then proceeds slowly, and oogenesis steadily, whilst nest‐burrows are renovated and a noisy nocturnal display occurs. Fertilization perhaps takes place ashore after which there is a pre‐laying exodus lasting about three weeks. During this absence at sea the single large egg (about 16 per cent of the female's body weight) matures and the flocks then return for the laying period. The males take the first incubation shift and fast of eleven to fourteen days while the females go back to sea. At initial landfall, and at the time of egg‐laying, both sexes contained abundant depot fat. After their incubation fast the males are relatively lean. The incoming females, on the other hand, are fat. This alternation of fat deposition at sea, and utilization ashore continues during the incubation period of fifty‐three to fifty‐five days. Only one egg is laid per year. Out of season, or even out of phase, breeding is unknown. The seminiferous tubules are already in a state of lipoidal and cholesterol‐positive metamorphosis at the time of egg‐laying when the males take the ...