noddies typically occupied portions of branches closest to the 

 trunk. Brown noddies nested almost solitarily in the Cocos 

 canopy on South, were found within dense colonies of black 

 noddies and white terns in tall Pisonia forests, with red-footed 

 boobies and great frigatebirds in Tournefortia, and amidst 

 sooty tems and red-tailed tropicbirds (Bo'sun Bird Islet). 

 Apart from a few ground nesters on Raurau and Fishball, the 

 only ground-nesting colony (80 nests) was located on a 

 Portulaca mat on Noddy Rock — a site free of predators, 

 although flooded during storms. 



Brown noddies often formed loose roosting "clubs" on the 

 atol 1 ' s beaches. Aggregations of 1 5-20 birds were found on the 

 west coast of South and on Sandy Inlet, south-central Nake. 



Numbers : Clapp & Sibley ( 1 97 1 a) estimated a population 

 of 1,000 birds in June 1965, with about 800 birds breeding 

 (with eggs and young). We estimated a total population of 

 1,491 breeding pairs (Table 1 ). Because nests high in Cocos 

 palms were difficult to detect, we undoubtedly overlooked 

 many, and our estimate of approximately 3.000 birds is 

 conservative. Although larger than the population estimated 

 by POBSP (Clapp & Sibley, 1971a), uncertainties about the 

 1965 survey coverage (F. Sibley, personal communication) 

 prevent us from knowing if Caroline's population has changed 

 over the past 25 years. 



Phenology : On Christmas Island, the timing of egg laying 

 varies between colonies. In general, peak laying occurs from 

 March to May, and from November to December. On Caroline, 

 mating and nest-building were found in March 1990, but by 

 May only a few eggs had been laid. Eggs and young were found 

 in June 1965 (Clapp & Sibley, 1971a) and in September 1988 

 (present study). We found 246 nests in September 1988 and 

 determined the contents of 106: 103 held eggs, 3 held downy 

 chicks. The incubation period is 35-37 days (Dorward & 

 Ashmole, 1963), so all viable eggs had been laid within the 

 previous 40 days (mid-August to late September). Because 

 many nests were being built, we feel confident that laying 

 continued into October. Clearly more research is needed to 

 determine whether laying occurs in regular cycles. 



Black Noddy ( Anous minutus) (Fig. 14) 



The black noddy is widely distributed in the tropical 

 Atlantic and Pacific. It is abundant in the Line and Phoenix 

 Groups, with populations of 16,000 estimated in the Phoenix 

 Islands (Clapp, 1967) and over 46.000 in the Line Group. 

 Centers of abundance are Palmyra (20,000) and Christmas 

 (14.500) (Perry, 1980). 



Distribution and Habitat Preference : The black noddy is 

 a tree-nesting species that on Caroline prefers tall stands of 

 Pisonia. The largest colonies (61% of the population) were 

 found in the grand Pisonia forests (to 25 m) on Pig and North 

 Pig, We found breeding birds on 18 motus. with colonies 

 exceeding 200 pairs in the Pisonia on Nake, Long, Arundel, 

 and Bird (Fig. 14). The only significant colony not primarily 

 associated with Pisonia was found on Tridacna, where 

 approximately 230 pairs nested in the tallest (ca. 8 m), most 

 central Toumefortia-Morinda forest. Black noddies always 

 nested in dense colonies near islet centers and were integral 



components of these plant communities: their droppings, 

 coating the ground with a film of guano, constantly enriched 

 the islet's meager soils. 



Numbers : Clapp & Sibley (1971a) estimated that 

 7,000 ± 25% birds were on Caroline. During our visit the 

 population was much larger: 5,122 pairs were estimated for Pig 

 and North Pig alone (Table 1 ). Basing our numbers primarily 

 on the densities of sampled colonies in Pisonia, we estimated 

 that nearly 8,400 pairs were nesting during our 1 988 visit. Our 

 population estimate approached 17.000 birds, to which an 

 unknown number of nonbreeding birds could be added. These 

 values place the Caroline population far above that for 

 Christmas, making it the largest known population in Kiribati. 



Phenology : Black noddies were just beginning a new 

 breeding season. On 27 September we observed hundreds of 

 birds gathering Tournefortia leaves floating along the windward 

 shore (Long) or flying with fresh leaves to their nests (Pig, 

 North Pig). Of the 1,085 pairs counted on transect, 536(49%) 

 perched as pairs, were defending nest sites, or were building 

 nests. An additional 273 pairs were attending nearly-completed 

 nests but were not incubating. The remaining 276 pairs were 

 incubating. Thus, 75% of the pairs had not laid eggs. The 

 contents of 230 nests were unknown, although we assumed 

 they contained eggs because of the incubating positions of the 

 adults. Of 46 nests into which we could see, 45 held a single 

 egg, and one contained a downy chick less than 5 days old. 



The breeding seasons for black noddies on Christmas 

 Island and Johnston Atoll peak in April and May (Schreiber& 

 Ashmole, 1970; Amerson & Shelton, 1976), where pairs are 

 highly synchronous, laying most of their eggs within a 

 2-3- month period. The Caroline colony, also synchronous, 

 but beginning egg-production in September, would be expected 

 to peak in October/November, six months out of phase with the 

 colonies further north. In 1990. however, black noddies were 

 just beginning to mate and nest in March, and by May some 

 were still sitting tightly on nests, while others had chicks in all 

 stages. 



Blue-gray Noddy (Procelsterna cerulea) 



Blue-gray noddies nest widely across the Pacific from the 

 Kermadec Islands to Hawaii. They are scattered throughout 

 the Line and Phoenix Groups. In the Line Islands, they were 

 formerly known to breed only on Christmas and Maiden 

 (Perry, 1980). Eggs are placed in nests minimally provided 

 with twigs and may be on coral rubble, sheltered under 

 vegetation, or under coral slabs to depths of I m (Rauzon 

 etai, 1984). 



The blue-gray noddy was recorded as "present" on Caroline 

 by Perry ( 1 980). Clapp & Sibley ( 1 97 1 a) noted birds over the 

 lagoon hut saw none on land. When we approached Caroline, 

 we saw two from the ship and later observed three Hying across 

 the lagoon. We also saw three birds perched on the leeward 

 islets, one each on the reef flats of Nautonga and Fitei. A third 

 bird Hushed repeatedly from a small clearing around a pile of 

 bottles on Raurau. but we failed to find a nest. In March and 

 May 1 990, we observed blue-gray noddies on all of the Southern 

 Leewards, plus Azure and Nautonga in the Central Leewards. 



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