Pandanus, so it is unlikely that these differences reflect changes 

 to the center of the motus. However, since the islets now appear 

 larger, accretions of coral rubble and sand that may have 

 occurred in the past 105 years, and are now barren or covered 

 only with herb mats, could account for most of the differences 

 (see Coral Islet discussion). 



Although we have no actual records of sooty tern colonies 

 on this chain of islets, in May 1990 AKK observed pre- 

 breeding swirls of this species over Lone Palm, Kota, and 

 Mouakena (Subchapter 1.2, Fig. 1 1 ). 



17. PANDANUS ISLET (7.36 ha) (Figs. 29,52; PI. 64) 



This motu was named by the present authors for its coastal 

 Pandanus grove, probably a drift-derived offshoot from a 

 parent colony on Nake. 



Physiography : Pandanus Islet, first in the chain, is 

 irregularly oval, 400 m long and 258 m across. It is nearly twice 

 the size shown on Arundel's map (ca. 3.4 ha). It occupies a 

 sheltered spot at the apex of the lagoon. Sand, actively filling 

 in the adjacent lagoon, is an important component of the 

 substrate on Pandanus, extending one-third of the way across 

 the islet. Although tidal reef flats are absent on the lagoon edge, 

 they average 75 m wide on the seaward side, producing a fairly 

 high proportion of rubble compared to the total land surface 

 (32%). 



Vegetation : Plant species total 10 (3 trees, 1 shrub, 

 6 herbs), 37% of Caroline's flora. Cocus, surprisingly, is 

 absent, despite the close proximity to Nake. Pandanus Islet has 

 four basic vegetation zones: natural herb mats, Toumefortia 

 scrub (with Pandanus), Tournefortia-Pisonia forest, and pure 

 Pisonia. Woodlands cover 62% of its area. The widest pioneer 

 mats ( 13 m) of any leeward motu occupy its east edge and 

 though sparsely vegetated (20% Heliotropium, 5% Lepturus, 

 5% Portulaca) reflect active growth toward the lagoon. 

 Proceeding west across the island, Toumefortia scrub (2 m 

 high), with pockets of pure Pandanus (10m high), merges into 

 Tournefortia-Pisonia forest (to 14 m high), whose bimodal 

 distribution suggests that the islet was once divided. The 

 seaward coast supports open Toumefortia (5 m high), beneath 

 which herbs eventually thin out onto the extensive reef flats. 



Birds : Five species of seabirds breed: masked booby 

 (2 pairs), red-footed booby (32 pairs), great frigatebird 

 (26 pairs), brown noddy (26 pairs), and white tern (52 pairs). 



Comments : Skinks and rats were observed, along with the 

 ubiquitous Coenobita and Cardisoma crabs. 



18. DANGER ISLET (2.71 ha) (Figs. 29,52; PI. 65,68) 



We named Danger Islet to commemorate the deep, shark- 

 infested channel to its north, a barrier that aborted our first 

 (dusk) attempt to survey the South Nake Islets. 



Physiography : Danger, shaped like a thickened comma, is 

 approximately 150 m long and 215 m wide. It is composed 

 almost entirely of coral rubble; interior humus is scant. Its reef- 

 channel flats are 21 m (north) and 14 m (south) wide. The east 



and west beaches, narrow and wide respectively, are typical of 

 all the leeward motus. 



Vegetation : Danger has 10 plant species (3 trees, 1 shrub, 

 6 herbs), 37% of the total flora. There are no introductions. The 

 usual concentric vegetation is clearly zoned: herb mats, 

 Toumefortia scrub and forest, central Pisonia, and Cordia in 

 the southwest. The herb mats are wide, extending 22 m and 

 15 m on the north and south shores, respectively. 



Birds : Four species of nesting seabirds were present in 

 1988: red-footed booby (139 pairs), great 

 frigatebird (26 pairs), brown noddy (26 pairs), and white tern 

 (52 pairs). 



19. BOOBY ISLET (0.84 ha) (Figs. 29,52; PI. 66) 



We named this motu, third in the chain, for its two species 

 of boobies, the common red-footed and rarer masked booby. 



Physiography : Booby, shaped like a teardrop, is 70 m long 

 and 1 25 m wide. Its coral rubble flats extend 1 m and 30 m on 

 the north and south sides, respectively. 



Vegetation : Despite its small size, the most notable 

 feature of Booby is its Pisonia forest. 20 m tall and undoubtedly 

 virgin. It occupies the exact center of the islet in a circle about 

 40 m in diameter. Surrounding this is Toumefortia scrub (to 

 8 m tall), thinning out to peripheral bands of coral rubble. 

 Although less than one hectare in size. Booby Islet's woodlands 

 occupy two-thirds of this area. Booby Islet has nine species of 

 plants (two trees, one shrub, six herbs), 33% of Caroline's 

 flora, and no introductions. 



Birds : Five species of seabirds breed: masked booby 

 (7 pairs), red-footed booby (52 pairs), brown noddy (2 pairs), 

 black noddy ( 1 pair), and white tern (6 pairs). 



20. CORAL ISLET (1.70 ha) (Figs. 29,52; PI. 66) 



Fourth from the north. Coral Islet was named for its reef- 

 derived coralline substrate. 



Physiography : Shaped like an arrowhead, Coral is 

 approximately 130 m long by 200 m wide, more than three 

 times the size mapped by Arundel (Fig. 4). Most of its area is 

 barely higher than the surrounding interislet channels. The 

 shallow reef flats between Coral and its two southern motus are 

 only several centimeters deep at low tide; all three may be 

 destined to unite. Unless closely inspected, they appear to have 

 already merged, a fact which, together with Bryan's incorrect 

 map (Fig. 6), helps account for the widely differing number of 

 motus attributed to Caroline. 



Vegetation : There are nine species of plants (two trees, 

 one shrub, six herbs), 33% of Caroline's flora, and no 

 introductions are present. Plant communities comprise a small 

 Pisonia forest (0. 1 3 ha), which is surrounded by the predominant 

 Toumefortia, which in turn is fringed with a narrow band of 

 native herbs. "Soils" are extremely coarse. 



Birds : Five species of seabirds bred in 1988: masked 

 booby (1 pair), red-footed booby (28 pairs), great frigatebird 

 (2 pairs), brown noddy (6 pairs), and white tern (15 pairs). 



43 



