shelf. Southeast Asia has long been recognized as an outstanding 

 area for fish and. until the last few decades, was similarly rich 

 in seabird colonies (Nelson. 1978). 



Regional Discussions 



Region I (457 birds. 26 species. 7 families) 



Region 1 (Fig. 1 ) begins with the waters between the Line 

 Islands and Hawaii north to 14°N. The Line Islands are a 

 scattered group of five atolls, five islands, and two submerged 

 reefs straddling the equator between 06°N and 12°S latitude, 

 and 162° and 150°W longitude. They are all low islands with 

 extremely varied ecology ranging from barren, tropical deserts 

 with scarcely any vascular plants to lush forests of coconut 

 palms and/or indigenous vegetation. 



All except three are uninhabited and thereby serve as 

 suitable habitats for tropical seabirds. Together with the 

 Phoenix Islands, they constitute the largest assemblages of 

 breeding tropical seabirds in the Pacific, both in species diversity 

 and abundance. Christmas Island, with 18 species of breeding 

 seabirds. is one of the richest seabird islands in the world 

 (Ashmole & Ashmole, 1967; Garnett, 1983), due in part to 

 equatorial upw ellings and plankton associated with the seasonal 

 movements of the North and South Equatorial Currents and 

 Countercurrents (King & Hida, 1957; Ashmole & Ashmole, 

 1967). 



Overall, we found greater seabird diversity and density in 

 the Line and Phoenix Islands (Tables 1,2,4). Two major groups 

 of birds were most abundant in Region I: shearwaters/petrels 

 and terns. Of minor importance numerically were boobies and 

 storm-petrels (Table 3). Of interest is the high proportion of 

 resident breeders and wintering birds (Fig. 3). 



The 1982-1983 anomalous warm waters associated with 

 the El Nino Southern Oscillation severely disrupted seabird 

 breeding on Christmas Island (Schreiber & Schreiber, 1984). 

 Furthermore, feral cats, developmental threats, and increased 

 poaching associated with expanding human populations arc 

 ongoing problems on Christmas, and these affect the numbers 

 of birds seen at-sea in the area (Gilbert and Ellice Islands Gov., 

 1974; Garnett, 1983; Teeb*aki, personal communication). 



In the Line Islands, we extended the known range of herald 

 petrel and added sightings of Cook's petrel (six) and Stejneger's 

 petrel (two), both rarely recorded in the area. 



Region 11 ( 1 ,796 birds. 24 species, 6 families) 



The Phoenix Islands (Fig. 1) form a relatively compact 

 group of eight low islands lying from 03 to 05°S. Most are dry 

 and waterless. All except Canton are uninhabited and harbor, 

 like the Line Islands, some of the richest and largest seabird 

 colonies in the world. They lie within the boundaries of the 

 South Equatorial Current (04°N to ca. 10°S), a region rich in 

 plankton and associated fish schools (King & Hida, 1957; 

 Ashmole & Ashmole, 1967). 



At-sea bird observations were dominated by sooty terns 

 (96Vr of total), with procellariids next in abundance (Table 3). 

 Small numbers of frigatebirds. boobies, and storm-petrels 

 occurred, as in Region I (Table 2). Resident breeders, 

 nonbreeding visitors and direct migrants were all well- 

 represented (Fig. 4). The highest density of any bird on this 

 cruise was in this area — sooty terns, at 32.45/10 km 2 . 



In the Phoenix Islands we recorded a range extension of 

 the little shearwater, and added three sight records of Cook's 

 petrel, and nine of wedge-tailed shearwaters (Table 6). Because 

 of the remoteness and unsuitability of the Phoenix Islands for 



Northern 



Mariana 



Islands 



Marshall Islands 





Papua New Guinea 



|»»»| ranrse wm ■uumiumb 



fl — ^ POLrTICM tiiu.c.".. 



[~T"1 CHUUi TB»C«. ««*P<I»« KOWOltv 



J,.s 



Fig. 8. Geographic distribution of feeding flocks (dots). 



245 



