In June, July, and September the entire study 

 area was occupied, although somewhat sparsely 

 in the northeast portion. In October and Novem- 

 ber the greatest densities were south of lat. 

 18° N., the southern half of the area, although 

 no part of the area was without a few birds. By 

 December birds left in the area were scattered 

 but had a density center at the southern end of 

 the area. 



Data in figures 7a, 7b indicate a possible 

 tendency for birds to enter the study area from 

 the southeast and to exit toward the southwest. 

 Analysis of the direction of movement from 

 field notes bears out this suggestion. 



Although no specimens of Black-winged 

 Petrels were collected during the study, speci- 

 mens taken at comparable latitudes west of the 

 area, as well as one subsequently collected 

 from the study area, make identifications of 

 this bird fairly certain. Very small numbers 



of White-winged Petrels (see next species ac- 

 count), Bonin Petrels, and possibly Cook's 

 Petrels Pterodroma cookii (Gray), may have 

 been present, but they would have had little 

 bearing on the numbers of Black-winged Petrels 

 observed. Without doubt this form was by far 

 the most abundant of the small Pterodroma in 

 the study area. 



White-winged Petrel 

 Pterodroma leucoptera (Gould) 



Status : Possibly uncommon visitor or migrant 

 during nonbreeding season. 



This species is included in the species ac- 

 count on the basis of the identification of at 

 least three birds in June 1965 in the study area 

 and the collection of specimens by POBSP per- 

 sonnel from comparable latitudes to the west of 



17 



