no. 3605 SEABIRDS — GILL 19 



at higher latitudes. The numbers of seabirds recorded by Bailey 

 (1966) off Arabia were also considerably greater than my counts 

 and serve to emphasize the highly localized nature of seabird distri- 

 bution in the Indian Ocean. 



The composition of seabird communities often changes markedly 

 during a year because of movements of seabirds that correspond to 

 changes in the availability of food items and/or that are a part of 

 extensive postbreeding migrations. In the Indian Ocean the most 

 striking seasonal differences are those found in the western Arabian Sea 

 (see Bailey, 1966; Bourne, 1960, 1963; Jouanin, 1957). In this area 

 there is, first of all, a resident seabird community, which includes 

 no less than eight endemic forms (four species and four subspecies). 

 The majority of its species occur primarily in the inshore waters 

 close to breeding and/or roosting stations (Bailey, 1966) with the 

 result that only a few, e.g., Bulweria fallax and Phaethon aethereus, 

 are encountered regularly as far out to sea as were the stations included 

 in this report. The presence of dark petrels, all apparently B. fallax, 

 at our stations in the Arabian Sea in January and February east 

 as far as 69°11' E suggests that Jouanin's petrel disperses widely at sea 

 from its yet undiscovered breeding stations near the Arabian coast, 

 at least during the nonbreeding season. Unfortunately, the southern 

 limits of these movements remain uncertain because of the difficulty 

 of separating it from other dark petrels. All my records were made 

 north of the equator (actually 00°31' S), but there is a specimen from 

 Kenya (Jouanin, 1957), and Bailey (in prep.) saw dark petrels "in- 

 separable from B. fallax south to 15° S." 



In May, coinciding with the onset of the monsoon winds, with the 

 consequent offshore upwelling, and with increased productivity, the 

 resident species of the western Arabian Sea are subjected to an influx 

 of large numbers of several migrant species from the subantarctic 

 Indian Ocean. Included in this arriving assemblage are three species 

 of storm petrels: Oceanites oceanicus and Fregetta tropica from 

 Kerguelen and the Crozet Islands (Bourne, 1960), and Pelagodroma 

 marina from breeding stations off southwest Australia (Morzer Bruyns 

 and Voous, 1964). All of my observations are in accord with the 

 known arrival times and distribution of these species in the northern 

 Indian Ocean, though actual records of Wilson's petrels near the 

 African coast may be noteworthy. 



Arriving from the same area as Pelagodroma is the large pale-footed 

 shearwater, P affirms carneipes. Unfortunately, the majority of 

 shearwaters I saw near the Maldive Islands in April did not come close 

 enough to permit positive identification; however, most appeared too 

 large, with too heavy a flight to be P. pacificus and consequently were 

 considered to be P. carneipes. A light bill could be discerned on a 



