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Black-winged Petrel 
( Pterodroma hypoleuca ) 
wer6 recorded regularly in the southern hemisphere# 
These birds probably represent individuals that have finished their 
breeding cycle earlyj or have had nest failures. 
Kennadec Petrel 
( Pterodroma neglecta ) 
Kermadec Petrels were recorded further north than any other 
tropical species of Pterodroma . Sightings were usually of single 
birds and were distributed over four areas. Color-phases recorded 
are: 1 dark, 6 light with chest bands in the northern hemisphere, 
3 light without chest bands in the southern hemisphere. The remaining 
U birds are a result of an estimate on a feeding flock of Pterodroma . 
Murphy Petrel 
( Pterodroma ultima ) 
Tnis species was recorded with some regularity between lO^S 
and 15°S. Its uniform light brown pattern, typical Pterodroma shape 
and flight, readily identify it once other dark shearwater/petre1s 
are known. In size it appears between the Kermadec Petrel and the 
Juan Fernandez Petrels although the physiognomy resembles P. externa . 
Cook Petrel 
( Pterodroma cookii ) 
This cold water species of Pterodroma was found most abundantly 
along the convergent zone ^of the California current and the warm water 
mass in the Cape San Lu area* Its flighty color pattern and white 
wing stripe aid in identification* 
White-winged Petrel 
(Pterodroma leucoptera ) . v 
This species was abundant in the south equatorial counter current* 
The population probably represents post-breeding bijpds from Mas Afuerra. 
The overlapping pelagic ranges of Pterodroma leucoptera and Pterodroma 
hypoleuca indicates a difference in feeding habitats which is as 
unknown* A careful analysis of environment and stomach contents of these 
two species should aid in answering questions on basic ecological 
concepts that would further the understanding of all species in the 
pelagic habitat* 
