The Nestling of the Sooty Shearwater

In an earlier paper on the breeding habits of the Sooty Shearwater (Ptififltis griseus) in New Zealand (Richdale, ,1944b: 102), it was necessary to withhold the story of the nestling.Accordingly, this paper will deal solely with the young shearwater from the time it begins to hatch until it leaves its island home.Data used herein were collected _ chiefly on Whero Island in the period from December 20, 1941, to March 14, 1942, but they are supplemented by important details gathered on a later trip of six weeks in 1943-44.In order to elucidate still further the behavior of the nestling, reference has been made to other species of petrels studied.Several points in the paper mentioned above need discussion and elucidation.The suggestion (Richdale, 1944b:99-100) that the 1943-44 season was a late one proved wrong, for the hatching dates, as noted in table 1, were normal.In fact, three chicks hatched a day earlier than in any of the preceding years.This means that my estimation (page 100) of the average incubation period of eight weeks is correct.It will be noted (page 99) that I found no eggs in 100 burrows on Taieri Island, about 20 miles south of Dunedin, on November 20, but 24 were recovered on November 27.From November 20 to January 17 is 58 days, which means that average incubation is not longer than this and according to further information given on the same page very little less than 58, and certainly more than 51 days.Finally my remarks (page 100) that the span of egg-laying is short are ' correct.Hatching on Whero Island in 1943-44 of 59 chicks occupied 18 days so that eggs must have been laid in a similar or slightly shorter period.