Failure to launch: evidence of protracted parental care in albatrosses

Abstract

Most albatrosses have well defined breeding seasons (Tickell 2000). Fledging tends to be spread over a longer period than laying or hatching because the duration of the chick-rearing stage is more variable than that of incubation (Warham 1990). However there are few records of albatross chicks extending fledging periods by more than a month or two (but see Brown & Adams 1984). We were thus surprised to see a juvenile Sooty Albatross Phoebetria fusca on a nest near the meteorological station on Gough Island (40°20'S 9°55'W) during the 2014-15 breeding season, three months after Sooty Albatross chicks usually fledge from Gough Island (Ryan 2007; most chicks fledge in May-June, and in 2015 the last chick near the weather station departed between 17 and 25 July). The late-fledging juvenile was first observed on 17 September 2014 and remained on its nest until at least 14 October, but apparently fledged by 19 October (the nest was empty, and no carcass was found). It seemed to be in good health throughout this period, and on being approached, it clapped its bill in the manner typical of a large nestling. Characters that indicated it was a juvenile bird still in its first year were the virtual lack of a white eye-ring, no yellow sulcus stripe on the bill, and uniformly aged, fresh plumage still with pale fringes to the back coverts (Figure 1; Marchant & Higgins 1990). Assuming a mean hatching date in mid December (Ryan 2007), this gives a fledging period of around 300 days, much longer than the 164 ± 9 SD days recorded at Ile de la Possession, Crozet Islands (46°25'S 51°45'E: maximum 178 days; Tickell 2000).