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Towiisend Shearwater 
( Puffinus puffinus auricularis ) 
A very abundant shearwater in the seas around the Revilla- 
Gigedo Islands. In March they were found farther north than in 
February, but this form probably has a limited pelagic range. 
Black-vented Shearwater 
( Puffinus puffinus opisthomelas ) 
This sub-species inhabits the cold California current, breeding 
on islands along the Baja Coast. It is readily identified from the 
predeeding form by its larger size, brownish back and dark flanks. 
Dark-rumped Petrel 
( Pterodroma phaeopygia ) 
Dark-rumps were found regularly in the equatorial counter current 
at 112°W. These birds appeared rich,brown dorsally, dilfering from e 
single sighting along the equator which was sooty black above. It is 
remotely possible that the northern population is P* £. sandwichensis 
from Hawaii. The southern bird was ^almost definitely P. £. phoeopygia 
from the Galapagos. 
Juan Fernandez Petrel 
( Pterodroma externa externa ) 
The scarcity of Juan Fernandez Petrels sightings along the rich 
counter currents is indicative of birds remaining on their non-breeding 
grounds during the breeding season. Most Juans appeared in bad molt 
with occasional individuals showing large white patches on the dorsal 
surface of thdir wings. These white patches were so pronounced that 
they gave me a first impression of being Daption . Mr. Heiden also 
observed this phenomenon on the Rockaway cruise. 
Tahiti Petrel ^ 
( Pterodroma rostrata ) 
Although this species is very difficult to separate from Phoenix 
Petrels, both individuals observed this trip came close enough to be 
positively identified. Factors making identification possible were: 
large size, worn light brown plumage, and massive bill-small head 
appearance. I believe that I saw a couple during nocturnal observations 
but listed them as Pterodroma s£. 
I 
