Monogamy in a long-lived seabird: the Short-tailed Shearwater

Abstract

Abstract Short-tailed Shearwaters Puffinus tenuirostris are 500 g burrow-nesting seabirds which breed colonially on islands and headlands in south-eastern Australia. On average, their breeding season occupies 195 days (53%) of each year (Warham 1990). For the rest of the year they are pelagic, making an extensive annual transequatorial migration within the Pacific basin. All 23 million Short-tailed Shearwaters are extremely synchronous in their laying, most of which occurs between 23 and 28 November every year, over the entire breeding distribution of the species. Only one egg is laid each year and lost or unsuccessful eggs are not replaced. Up to one million of the large young of Short-tailed Shearwaters (muttonbirds) have been harvested annually for over a century. Concern about this exploitation resulted in the establishment in 1947 of a study that still continues, allowing analysis of the complete reproductive careers of all individuals in one population.