communities are present: peripheral herb mats (including 

 leeward Portulaca with Suriana), Toumefortia scrub and 

 forest ( to 6 m high ) bordered with Cordia, and a central Pisonia 

 forest. Larger trees had up to 15 trunks and multiple root 

 suckers. Measurements of 10 trees (main trunks) averaged 

 15 m in height, 140 cm in circumference (at 1 .5 m), and 243 cm 

 base circumference. Distances to nearest neighbor for 10 trees 

 averaged 4.2 meters. As on its neighbor islets, the Pisonia 

 forest on Brothers is striking, especially since it has matured to 

 a closed-canopy monotypic stand devoid of any subcanopy 

 species (Fig. 40), evidently in about 65 years. In 1920, Brothers 

 Islet was planted with 315 Cocos palms, which covered 

 approximately 97% of the usable land area (Table 13). 



Birds : Four species of seabirds bred: red-footed booby 

 (25 pairs), brown noddy (8 pairs), black noddy (15 pairs), and 

 white tern (50 pairs). In May 1990, large numbers of sooty 

 terns swirled over Brothers and North Brothers Islets. 



Comments : Many of the mature Pisonia trees contained 

 capacious cavities in their boles that housed large coconut 

 crabs. In March 1990, several of these holes had feathered 

 skeleta of sooty terns (and possibly also brown noddies) 

 outside their entrances, along with freshly-snipped Pisonia 

 branches (see Subchapter 1.2, Coconut Crabs section). 



12. NODDY ROCK (0.02 ha) (Figs. 27.47; PI. 19) 



We named this ninth motu in the Windward Islets for its 

 only known breeding seabird, the brown noddy. In September 

 1988. at least 80 pairs were incubating their eggs on the 

 Portulaca mat that covers its central lee section. 



Noddy Rock, an eroded limestone plateau (feo), is 26 in 

 wide by 9 m long. It is windswept and salty, with waves 

 splashing over its eastern edge on most days (it rises only 

 0.5 m above high water). During storms it is completely awash 

 ( Anne Falconer, personal communication ). Only three species 

 of plants (11% of Caroline"s flora) grow here, thinly covering 

 the western (leeward) third of the island in the following 

 proportion: 75% Portulaca, 20% Lepturus, and 5% 

 Toumefortia). 



13. NORTH ARUNDEL (0.91 ha) discussed below 

 (Figs. 29,34.47; Pis. 14.62) 



14. ARUNDEL (7.34 ha) 



Arundel Islet was named last century in honor of John T. 

 Arundel. A British trader and guano digger. Arundel was one 

 of the leading figures in the Pacific phosphate industry . directing 

 guano and coconut planting operations on Caroline and other 

 islands from 1873 to 1897. His most valuable contributions, 

 however, were his excellent surveys and maps of several 

 central Pacific islands, including Caroline (Fig. 4). The islet 

 immediately to its north. Arundel's "cap." we named North 

 Arundel. 



Physiography : Arundel's shape is a I at crescent, with 

 wedge-shaped North Arundel lying across a short channel 

 immediately to Us north. North Arundel is 80 m long x 1 30 m 



wide, while Arundel is 375 m long x 210 m wide. They are 

 composed almost exclusively of coral rubble and Hanked on 

 their inneredges by Acropora reefs heavily laden with Tridacna 

 clams. Arundel's inner "horns" have evidently added more 

 sand and rubble since 1883 (Fig. 4). 



Vegetation : There are 1 1 plant species (3 trees. 1 shrub. 

 7 herbs) on Arundel, 41% of Caroline's total. There are no 

 introductions. North Arundel has 1 1 (4 trees, 1 shrub. 6 herbs), 

 41% of Caroline's flora, including one introduction, Cocos. 



The vegetation on this pair of motus, along with Tridacna 

 to the south, consists of extensive herb mats, low scrub and 

 small interior forests (Fig. 34), slightly less lush than the more 

 northerly windward motus. Their woodlands are primarily 

 Toumefortia, with a thin belt of Cordia and central Pisonia 

 groves (a bilobed pattern on Arundel). Morinda is unusually 

 common in Arundel's central forests, and Achyranthes is 

 especially abundant on North Arundel. Pisonia occupies only 

 13% of the land area on Arundel, compared to 46% on Pig. 

 Soils are extremely rubbly . with scant organic matter, a possible 

 legacy of the guano era. 



Both North Arundel and Arundel were heavily planted 

 with Cocos in 1919-20 (69 and 646 palms, respectively). All 

 usable land was cleared (Table 13). Despite the extreme 

 paucity of Cocos today, the relatively scant Pisonia present 

 today on these islets, compared to those further north, suggests 

 that the Cocos plantations were more successful here. Their 

 proximity to South probably also guaranteed better maintenance. 



Birds : Five species of seabirds bred on Arundel: red- 

 footed booby (37 pairs), great frigatebird (on territory, 

 September 1988; breeding confirmed, early 1989 by Anne 

 Falconer), brown noddy (1 1 pairs), black noddy (249 pairs). 

 and white tern (227 pairs). In May 1990, thousands of sooty 

 terns swarmed above Arundel and North Arundel. 



15. TRIDACNA ISLET (9.08 ha) (Figs. 29.48,49; 

 Pis. 1,26.48.62.63) 



The 13th and southernmost motu in the windward chain 

 was named by the present authors and Boris Sirenko for its 

 outstanding coral reef studded with giant clams {Tridacna 

 maxima). 



Physiography : Somewhat crescentic. measuring 446 m 

 long and 250 m wide, Tridacna is one of the largest motus on 

 Caroline. Its ground surface is heavily littered with coral 

 rubble, having a sandy strip above the beach crest on the 

 windward edge. 



Vegetation : There are 1 3 plant species (2 trees, 2 shrubs, 

 9 herbs), 48% of the atoll's flora. For its size, Tridacna's 

 \ egetation is surprisingly lacking in tall forests, a legacy of the 

 910 Cocos palms planted on 82% of its available land area 

 (Table 13). Vegetation patterns follow the usual concentric 

 zonation: peripheral herb mats border a discontinuous belt of 

 Suriana (windward side), while the large central mass is 

 dominated by scrubby Toumefortia— Morinda woodlands, 

 which cover 88% of the islet's area, yet only attain 7 m in 

 height. In cross-section (Fig. 49). the short woodlands are 

 particularly noticeable. Compare the present lack of Cordia. 



40 



