Mannikiha's maximum dimensions are 700 m long and 

 375 m wide. On the lagoon side, the serub skirts high water, but 

 when the tide drops, a strip of blinding white sandy coral lines 

 the lagoon. To seaward, upraised reef, beachrock, and successive 

 layers of gray coral rubble stretch in a wide swath (40 m) 

 toward the outer reef, 130 m distant. Throughout the islet the 

 substratum is gray coral rubble, with some exposed reef flat 

 hardpan in the northeast. Having numerous seabirds, this motu 

 might have also contained productive guano deposits. 



Vegetation : Mannikiba, the fourth largest motu, harbors 

 1 3 plant species: (4 trees, 2 shrubs, 7 herbs), 48% of Caroline's 

 flora. One of its shrubs (Species A), a new record for Caroline, 

 has yet to be identified. The only introduction is Cocos, 

 occupying 0.1% of the land area. 



Mannikiba' s vegetation, denser toward the north end, is 

 clearly zoned: herb mats, Tournefortia scrub and forest, and 

 scattered Pisonia groves. The few clumps of peripheral Cocos 

 are probably not drift-derived but the remnants of 6,000 "seed 

 sets" brought from Flint Island in June 1920. These were stored 

 on Mannikiba and "used to replant misses on other islets" 

 (Young, ca. 1922). 



Pisonia, though present, occupies only 5% of the land 

 area, a small percentage for such a large islet. This suggests that 

 a large portion of the interior forests were felled to accommodate 

 the coconut "sets." This is also confirmed by the presence of 

 several old cut stumps in the interior. A century ago, Holden 

 & Qualtrough ( 1 884) noted that "About one-third the distance 

 up the lagoon a canvas hut exists on one of the smaller islets on 

 the eastern side of the lagoon, and two wooden huts stand on 

 one of the western islets, some distance further up the lagoon." 

 Mannikiba, the largest western islet, situated about halfway up 

 the lagoon, was most likely the site of the wooden huts, erected 

 around 1 920 and used for the following few years when the new 

 company, S. R. Maxwell & Co., Ltd., was anxious for the 

 success of Caroline's plantations. Although nothing more is 

 known of Mannikiba's history, collection of guano from its 

 numerous seabirds, including large populations of frigatebirds 

 and sooty terns, may account for further past disturbance. 



Transect 1 ( north-central sector, PI . 7 1 ) passed through the 

 heart of a fine interior forest, while Tr. 2 (south-central sector) 

 passed through scrub and herb mats, which may represent part 

 of the former Cocos "nursery." Profiles through these two 

 cross-island transects resemble those from Brothers (Fig. 46) 

 and an old interisland channel on Long (Fig. 40), respectively. 



The low, peripheral herb mats (absent from the lagoon 

 side) are composed of 30% Heliotropium, 20% Boerhavia, 

 1 5% Tournefortia, and less than 1 % of Portulaca and Laportea. 

 They are best represented in the southern sector. The 

 Tournefortia forest, 6 m high on both sides, is thick, having 

 95% canopy coverage. The Pisonia forests, though fragmented 

 (12m high, 1 00% canopy cover), contain Morinda, Boerhavia, 

 Achyranthes, Laportea, and Phymatosorus, but none cover 

 more than 1 0% of the ground area. 



Seabirds : Six species of seabirds are known to breed: red- 

 footed booby ( 184 pairs), great frigatebird (287 pairs), brown 

 noddy (161 pairs), black noddy (176 pairs), and white tern 



(195 pairs). No sooty terns nested on this islet in 1988, but 

 Clapp & Sibley ( 1 97 1 a) estimated 2,500 pairs in 1 965, and the 

 Falconers reported large colonies on Mannikiba, Blackfin and 

 Matawa in July-August 1990. 



Comments : Coconut crabs live in the Cocos grove. 

 Azure-tailed and snake-eyed skinks (Cryptoblepharus 

 poecilopleurus), as well as a gecko, were noted in 1990 (DHE, 

 G. Wragg, personal observation). 



25. BLACKFIN ISLET (2.62 ha) (Figs. 29,54; Pis. 3 1 ,73 ) 



We named this motu, second in the Central Leeward chain, 

 for two exhilarating shark attacks (near misses) within its 

 northern surge channel. 



Physiography : Blackfin, shaped like conjoined ovals, is 

 140 m long and 190 m across. Coral rubble covers 30% of its 

 surface; all beaches and upper reef flats are of variable widths, 

 due in part to the fact that it has. in the recent geological past, 

 incorporated a smaller, circular motu into its northern confines. 



Vegetation : Blackfin Islet has nine species of plants (three 

 trees, one shrub, five herbs), 33% of Caroline's flora. The only 

 introduction, Cocos, is rare. Four plant communities were 

 identified. Herb mats are well represented, especially around 

 the newly incorporated islet. The Tournefortia scrub, 21 m 

 v/ide in the east, is short (to 2 m), but approaches the stature of 

 a forest (to 6 m) in the west. The central forests of Cordia and 

 Pisonia (0.41 ha) are 9 m high. 



Birds : Three species of seabirds bred in 1988: great 

 frigatebird (4 pairs), brown noddy (37 pairs), and white tern 

 ( 1 1 pairs). In May 1990, one red-footed booby sat tight on a 

 nest, while two months later large numbers of sooty terns began 

 laying. 



26. MOTU MATAWA "White Tern Islet" (1.71 ha) 

 (Figs. 29.54; PI. 55: Subchapter 1.2, PI. 3) 



On arriving at this islet, the authors were swarmed by 

 1 5 white terns, all hovering within arm's reach and exhibiting 

 the ethereal grace that inspired their former common name, 

 fairy tern. I-Kiribati (Gilbertese) call them matawa. 



Physiography : Of oval shape, Motu Matawa is third from 

 the north in the Central Leeward chain. It is 105 m long and 

 190 m wide. The entire motu, like all of Caroline's small to 

 medium islets, is built of coral rubble of varying grades, whose 

 unvegetated portion comprises one-fourth or more of the land 

 area. Its lagoon beach is 2.5 m wide, while the seaward beach 

 (sparsely vegetated) is 6 m wide. 



Vegetation : Matawa has 10 species of plants (4 trees, 

 2 shrubs, 4 herbs), 37% of Caroline's flora. There are no 

 introductions. The usual plant communities were present, 

 dominated by Tournefortia (to 7 m), which covers half the islet. 

 Vegetation is less lush and more open as one progresses south 

 on the leeward side. Coral rubble, flanking the beaches and 

 extending further inland, also becomes more evident. The east- 

 central Pisonia-Cordia forest (to 8 m) rises barely higher than 

 its surrounding Tournefortia. 



45 



