insufficient to be certain of the breeding season. 
Other Specimens : USKM J00697, cf, 17 May 1925; USHM 5 OO 698 , $, 17 May 1925. 
POBSP Specimens : USMM 492967 , < 3 , 12 March 1965; USMM 4-94122, ?, ovary 5 mm., 
' . t 
510 gms., 13 March 1965; USHM 494123, te. 15 x 10 ram., 13 March 1965 . 
% 
Bonin Island Petrel (Pterodroma hypoleuca) 
t 
Current Status : Breeds annually. 
Prior Records : This species is not mentioned by Kittlitz ( op. cit . ) in 
his account of the Visit to Lisianski by Isenbeck in 1828. The only petrel 
described in this account is the Hedge-tailed Shearwater ( Puffinus pacificus ). 
Palmer and Muiiro found burrows all over the island in late June 1891 * (Munro, 
op . cit . ). Only a few fledged young were left, and they felt that the 
breeding season was over. 
1 * t 
Wetmore (unpub. notes, 1923) saw a few in May 1923, &nd estimated about 
n \ 
50 birds to be present on the island. Those he collected were sexually in¬ 
active. Their burrows were found only in the vegetated area of the island. 
Population : About 500 birds were noted in the air by Richardson (pers. 
t 
comm. ) in March 1954. Adults have been noted on each POBSP visit to the 
island. Many thousands were present in March 1963 when the species Were 
nesting. In March 1964 the population was estimated at 100,000, while in 
March 1965 it was placed at one million. Birds returned to the island in 
"great clouds" (W. O.W., II) at dusk, and were so numerous in the »air that 
they were frequently observed to brush together in flight ( ibid .). On 
this latter trip a major portion of the. two nights spent ashore was devoted 
to banding this species, and the population estimate is based on the number 
of birds per acre in the area covered by banding operations. As the species 
0 * 
has been found uniformly distributed over the island it is likely that this 
