14 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 12s 



with the Pacific gadfly petrels at sea, concurs in this identification 

 after examining my field notes and sketches. 



Ptcrodroma species 



An unidentified large, greyish-brown (=grey?) petrel with a darker 

 head and tail and white underparts was observed west of the Seychel- 

 les Islands at 05°23' S, 48°08 / E, on June 1. There was a pronounced 

 dark stripe on the upper wing surface and the underwings were white 

 with broad black margins. The flight consisted entirely of pendulum- 

 like swooping motions with no flapping. 



Bulweria fallax Jouanin's Petrel 



In January and February medium-sized, all-dark petrels were seen 

 regularly over most of the Arabian Sea between Bombay and Socotra. 

 The majority of these could not be identified positively because of 

 the difficulties involved in the separation of this species from Puffinus 

 pacificus and perhaps some Pterodroma petrels; however, a few positive 

 identifications of B. fallax were obtained and all individuals seen 

 at close range proved to be this species ; consequently, I have included 

 here all unidentified dark brown petrels seen in the Arabian Sea 

 from the Anton Bruun. Positive identifications are indicated in 

 table 7 by an asterisk. 



Using these criteria, 104 " Bulweria fallax" were seen during 64 

 hours of intensive surveillance between Jan. 27 and Feb. 10. Several 

 small flocks (up to 50 birds) were encountered near Socotra, where 

 the species was most common. My southernmost record was of 

 four individuals at 00°31' S, 54°56' E, on Feb. 10. 



In late May, Jouanin's petrel was the most commonly observed 

 pelagic species on a course paralleling the Arabian coast. At least 

 53 B. fallax plus an additional 16 petrels that were either this species 

 or Puffinus pacificus were seen between 22°59' N, 65°42 / E, and 02°02' 

 N, 51°11' E, in 17 hours of observation. 



The flight of B. fallax consists of five or six quick flaps followed by 

 a glide low over the water or a swoop down to the water from the 

 extra height it has gained. Only occasionally does the petrel swoop 

 in the pendulum fashion of some Pterodroma and, when it does, its 

 flight hardly seems fast or erratic. The shearwater-like flight pattern 

 seems to be used when the bird is foraging and the pendulum motion 

 when it is travelling, though the force of the wind is also an important 

 factor (see Bailey, 1966, p. 240). Although I saw groups of this 

 petrel near Socotra, single individuals usually were encountered. 

 On occasion they were seen to land on the water for extended periods 

 of time and appeared to be feeding on squid. 



