In summer 1990, Alexandre Falconer found one small 

 blue-gray noddy chick, attended by its parents, on an open 

 expanse of coral rubble on Motu Eitei, the first breeding record 

 for Caroline. Eitei is adjacent to Raurau, which we predicted 

 was the most likely breeding location for this species. 



Blue-gray noddies evidently breed in very small numbers 

 on Caroline. Nests are hard to find, given their cryptic placement, 

 the small number of birds present, and the extent of open 

 habitat (67.7 ha of herb mats and 41 .4 ha of consolidated coral 

 rubble). 



White Tern (Gygis alba) (Fig. 15, PI. 3; Subchapter 1 . 1 . PI. 55) 



The white tern is a widely-distributed pantropical species 

 occurring in moderate numbers throughout the Line and Phoenix 

 Groups. Clapp ( 1967) estimated 10,000 birds in the Phoenix 

 Group, and Perry (1980) estimated 17,050 birds for the Line 

 Islands. 



Distribution and Habitat Preference : White terns, the most 

 widely distributed breeding bird on Caroline, nested on 32 of 

 the 39 motus (Fig. 15). The only islets not occupied were tiny 

 and sparsely vegetated. 



White terns nested from 1 to 15 m above the ground, 

 wherever a branch or frond provided a relatively stable platform 

 in Tournefortia (PI. 3), Pisonia, Cordia, Pandanus , or Cocos 

 (Subchapter 1 . 1 , PI. 55). They did not form dense colonies but 

 were scattered from the edge to the center of each islet, even on 

 the windward sides, although they normally selected sites not 

 directly exposed to the prevailing trade winds. They utilized 

 isolated trees, scrub, or forest. An unusual departure from the 

 white tern's usual mode of "nesting" was an egg laid in an old 

 black noddy nest, 6 m up in an 8-m-tall Tournefortia on 

 Tridacna Islet. 



White tern densities varied from islet to islet (Table 7). At 

 one extreme, we found only two nests on Raurau 

 (0.07/1,000 nr). Densities on other islets ranged from 

 0.75/1,000 m 2 (Shark) to 6.67/1,000 nr (Nautonga) with a 

 mean density of 1 .38 pairs/1 ,000 nr of woodland. Overall, the 

 Windward Islets supported the highest densities. Although 

 white terns also nested in anthropogenic forests, their densities 

 were low: we believe that the low densities on South Island and 

 the Southern Leewards (Table 7) are attributable to man. Of 

 South' s 104.47 ha of vegetated land, only 4.2 ha (4.4%) was 

 native woodland (Subchapter 1.1, Fig. 50); fully 84% was 

 either Cocos (18.3 ha) or Cocos-lpomoea (62.5 ha) forest. 

 Although most of the Southern Leewards are covered in 

 unmodified natural forest, central Ana-Ana has been partly 

 cleared (0.21 ha) to accommodate thatched huts and a garden. 

 The activities of a family of four, with a dog and cat (until 

 October 1990), have apparently depressed the white tern 

 population on Ana-Ana and, perhaps, even on nearby islets. 

 We found no white terns on Ana- Ana during our visit, although 

 the Falconers, who vacated the atoll in summer 1991, assured 

 us that they occasionally nested. 



Numbers : We used the total woodland area of each islet 

 to calculate islet populations (Table 1 ) from our transect data. 

 More birds were found on the largest islets except South Island. 

 We estimated 1,094 pairs for Nake, 751 pairs for Long, and 

 nearly 400 pairs for Tridacna; these 3 islets accounted for over 



half the population (and over half the native woodland). We 

 estimated that 3,957 pairs bred on Caroline. This doubles the 

 numbers of Clapp & S ibley ( 1 97 1 a) and cited by Perry ( 1 980) 

 and exceeds by 3,000 the largest population formerly known 

 for the Line Islands. 



Phenology : Of 569 pairs of white terns recorded on 

 transect, 437 were roosting without obvious signs of eggs or 

 chicks, 107 were incubating, and 25 had chicks (often adults 

 were not present). Of the 25 chicks recorded, 17 were downy, 

 7 retained extensive traces of down with remiges, and 1 was 

 almost ready to fly. Incubation takes about 36 days ( Ashmole, 

 1963); young may require from 40 to 96 days to fledged 

 (Gibson-Hill, 1950; Ashmole, 1968). Nearly all chicks were 

 far from Hedging and were less than 4 weeks old. 



On Christmas Island, Schreiber& Ashmole (1970) found 

 that peak laying occurred in April-August each year, with 

 some laying in each month. On Caroline, Clapp & Sibley 

 (1971a) noted that about half of the birds had eggs, half had 

 young in June 1965. In March 1990, we found only a few eggs 

 and downy chicks, but in May a larger number of pairs were 

 breeding, with eggs and chicks in all stages. Although we 

 found that white terns on Caroline do lay during the peak period 

 on Christmas, it was clear that in 1 988 most eggs were laid after 

 mid-August. 



Other Birds on Caroline Atoll 



Seven species other than seabirds have now been recorded 

 on Caroline. Six of them are migrants (five shorebirds and a 

 long-tailed cuckoo). The reef heron is apparently resident, 

 although no nest has yet been found. 



Reef Heron (Egretta sacra) 



We found 15 reef herons scattered on 8 islands: Nake (1), 

 Long (2), Pig (1), Brothers (3), South (2), Mannikiba (2), 

 Matawa(l), and Emerald (2), as well as on the open reef flats 

 ( 1 ). Although birds were found on both the seaward and 

 lagoonward sides of the islets, most were along the lagoon 

 edge, as also found by POBSP in 1965 (Clapp & Sibley, 

 197 la). We estimated that approximately 30 birds were using 

 the atoll. We found no signs of breeding. Of the 15 individuals 

 we observed, 5 were dark, 8 were white, and 2 were of the pied 

 morph. 



Lesser Golden-plover (Pluvialis dominica) 



This plover used the beaches and herb mats, generally to 

 seaward. In September 1988, we found them on Nake (1), 

 Long (4), Tridacna (4), and Mannikiba (1), estimating a total 

 population of 20-30 birds, the same number found by POBSP 

 (Clapp & Sibley, 1971a). In March 1990, we observed eight, 

 and in May, three, all in winter plumage. 



Wandering/Siberian Tattler (Heteroscelus incanum or 

 H. brevipes) 



In September 1988, we located 18 tattlers on 6 different 

 islets: Nake (3), Long (3), Crescent ( 1 ), Arundel (2), South (7), 

 and Emerald (2). All birds were either alone or in pairs and 

 generally remained in the intertidal zone, although they often 



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