The island of North Keeling
C. A. Gibson-Hill published this comprehensive natural history of North Keeling in 1948, based on two field visits made in 1941 while he was stationed at the trans-Indian Ocean cable relay on the neighbouring Cocos-Keeling atoll. The article constitutes the first systematic account of the island’s geology, vegetation, and fauna, filling a gap left by the brief earlier observations of Guppy (1888) and Wood-Jones (1906), and it situates North Keeling within a broader comparative framework with Christmas Island.
Summary
Gibson-Hill’s article is structured around the island’s physical and biological zones rather than a chronological narrative. He divides the vegetation into four clear-cut units — the Pisonia-Cocos belt, the Tournefortia fringe, the Pemphis clumps, and the open bare spaces — and then examines the fauna associated with each. The dominant theme is the extraordinary concentration of sea-birds, particularly the Red-footed Booby and two species of frigate-bird, whose breeding colonies occupy specific microhabitats and follow rigid seasonal rhythms. Gibson-Hill documents these colonies in considerable detail, recording nest dimensions, egg measurements, chick development stages, and behavioural observations that reveal the social dynamics of each species.
A secondary but important thread runs through the article: the history of human exploitation of the island. The Cocos-Keeling islanders had been visiting North Keeling regularly since the 1830s to hunt sea-birds with bamboo poles and, later, to fell timber for boat-building under the Clunies-Ross family’s direction. Gibson-Hill traces how these activities shaped the present vegetation (the near-elimination of Cordia subcordata) and the bird populations, and he notes that the cessation of timber operations in 1929 — when no suitable overseer could be found to replace a dead Clunies-Ross relative — effectively ended systematic human pressure on the island. The wreck of the German cruiser Emden in 1914, driven onto the reef after her defeat by the Australian cruiser Sydney, provides a dramatic interlude in this history, and Gibson-Hill appends a detailed account of the salvage operations that followed.
The article also functions as a taxonomic and biogeographical document. Gibson-Hill records the conspicuous absence of rats, lizards, earthworms, centipedes, millipedes, and termites — all present on the main atoll — and discusses the likely causes, including the island’s inaccessibility and the lack of suitable substrate. He sent series of bird skins to Dr. R. C. Murphy at the New York Museum for subspecific identification, and the faunal lists in the appendices represent the first complete inventory of breeding species on North Keeling.
Key Findings
- The Red-footed Booby (Sula sula rubripes) colony numbered between 8,000 and 10,000 birds of all ages, with just under 4,000 breeding pairs; the two frigate-bird colonies in the Pemphis patches each contained approximately 1,000–1,200 nests (pp. 77–80).
- The German light-cruiser Emden (3,592 tons) was driven onto the reef fringing the south coast of North Keeling on 9 November 1914 after being disabled by the Australian cruiser Sydney; roughly a third of the crew still on board were killed, and the islanders salvaged the wreck between October 1915 and January 1916, recovering between six and seven hundred tins of corned beef, salmon, and sardines (pp. 93–95).
- The Clunies-Ross timber operations, which employed 40–60 Cocos-Keeling Malays on the island for approximately three months at a time, ceased in 1929 when no replacement overseer could be found; the principal species felled was Cordia subcordata, mostly for boat-building (pp. 67–68).
- The lagoon occupies the greater part of the island’s interior and reaches a maximum depth of less than six feet at low tide; the only freshwater sources are two brackish wells, twelve to fifteen feet deep, which the islanders used for washing and cooking but not for drinking (pp. 68–69).
- Gibson-Hill’s party of twenty Cocos-Keeling islanders collected approximately five hundred Fregata and Sula carcasses on each of the two 1941 visits, continuing a tradition of bird-hunting that had been practised since the 1830s (p. 97).
- The White Tern (Gygis alba monte) population was estimated at between two and three hundred pairs; the Masked Booby (Sula dactylatra bedouti) was considerably scarcer, with a total of no more than fifty pairs inferred from the reproductive cycle and the number of nests found across both visits (pp. 74, 85).
Conclusion
Gibson-Hill’s definitive takeaway is that North Keeling represents a coral-island ecosystem of unusual purity and stability, its faunal assemblage shaped by the complete absence of mammalian predators and the long history of selective human predation on the more accessible bird species. The rigid synchrony of breeding seasons across all colonial species, the clear zonation of vegetation, and the absence of invasive fauna together mark the island as a natural laboratory for understanding the ecology of isolated oceanic atolls — a value that Gibson-Hill implicitly underscores by contrasting it with the more disturbed and humanised main atoll.
Context
- The article draws on Gibson-Hill’s own field observations from January and July 1941, supplemented by the oral knowledge of Cocos-Keeling islanders (particularly his boatman Sakmat) and the earlier published accounts of Guppy (1889) and Wood-Jones (1912); no archival collections beyond these were consulted.
- The study is the second in Gibson-Hill’s comparative programme on the Cocos-Keeling and Christmas Island groups (the first being his 1947 paper on the main atoll), and it established the baseline faunal inventory against which later changes — including the post-war introduction of rats — could be measured.