IV 

 N 799 



V 



N 34 



111 



N 495 



VI 

 N 22 



VII 

 N 65 



Fig. 5. Relative abundance of birds bj famil} in Regions I-III. 



Fig. 6. Relative abundance ot birds b\ tanuh in Regions [\ \ II See Fig. 5 

 for legend. 



Java. Indo-China, Malaya, and Borneo (Delacour & Mayr, 

 1946; King & Dickinson. 1975). There appear to be no records 

 from the central South China Sea, where we saw a single 

 juvenile, flying west, on 2? October at 05°49'N, 107°30'E, 

 a location equidistant (ca. 400 km I from Borneo, Vietnam, and 

 the Malay Peninsula. 



Nonmigratory. masked boobies generally occur within the 

 \ icinity of their breeding islands, hut the} roam far out to sea. 

 They characteristically follow ships: one-quarter of the birds 

 circled around or followed the R/V Akademik Korolev. 

 Juveniles-subadults accounted for two-thirds of our overall 

 sightings, especially in the Line Islands, where they breed. 



Red-footed Booby (Sula sulci) : This pantropical booby 

 ranges across the entire tropical and subtropical Pacific, breeding 

 in many localities. We observed 41 individuals in the Line. 

 Phoenix, and Caroline Islands. 



Although nonmigratory, the lack of subadult birds at some 

 colonies has given rise to the hypothesis that although adults 

 arc relativel) sedentary, many juveniles disperse from their 

 natal islands (Schreiber & Ashmole. 1970). Pacific Ocean 

 Biological Survey Program personnel have shown that red- 

 foots generally remain within the vicinity of breeding or 

 roosting areas, and that adults are seldom encountered more 

 than 80 km from land ( King. 1967). Our sightings conformed 

 to this pattern. For example, we passed 500 km east ol Palmyra, 

 which harbors the largest colony of red-loots in the world 

 (25.000). yet saw none. The only red-foots seen in the Line 

 Islands were three light morph adults, Hying east, within 

 I 10 km of Maiden Island, where approximate!) 2.000 birds 



TABLE 7 



Participation b\ species or species groups in 14 feeding flocks 

 alona the 14,892km cruise track. 



breed (Clapp. 1967). and 1 juvenile, also flying east, around 

 460 km northwest of Caroline Atoll. In the Phoenix Group, we 

 obsen ed one dark morph adult in a feeding flock about 100 km 

 equidistant from several islands. 



In the central Pacific, red-foots lay from February to 

 November, depending on the island and food supply (Nelson. 

 1978). In the Southern Line Islands, the maun' egg-laying 

 period from 1988 to 1989 was September to October (ICBP. 

 1990: Kepler era/., Subchapter 1.2, this vol. i. which may have 

 accounted for the small number of birds seen on our cruise. 

 During March and May 1 990, at-sea observations throughout 

 the Southern Line Islands recorded much larger numbers of 



238 



