A day at Christmas Island
H. N. Ridley, Director of the Singapore Botanic Gardens, published this natural history account in 1891 following a single day’s visit to Christmas Island aboard HMS Redpole in August 1890. The article documents the island’s flora and fauna in considerable detail and uses the observations to address the broader biogeographical question of how remote oceanic islands are colonized.
Summary
Ridley’s account is framed by the practical limitation of his visit: the Redpole could remain at Christmas Island for barely a day, and many trees were out of flower, restricting his ability to collect specimens. Despite this, he made several additions to the plant list previously published by Hemsley from J. J. Lister’s 1888 collections, most notably describing a new orchid, Saccolabium archytas, which he found in abundance on the island. The article moves from a description of the island’s physical geography and geology to a systematic survey of its vegetation and animal life, closing with a comprehensive checklist of all recorded species.
The geological discussion is a notable feature. Ridley describes the island as composed almost entirely of a hard, yellowish coral-limestone that weathers into pinnacles and angular projections, with cliffs rising in superposed layers that evidence slow elevation from the sea floor. He draws a detailed comparison with Fernando de Noronha off the Brazilian coast, where he had observed in 1887 the living coral reef passing directly into the same compact ringing rock. Using this parallel, he rejects Branner’s hypothesis that the rock was derived from hardened sand-dunes, arguing instead that it is consolidated coral-reef material. He further notes that large blocks of coral reef found at Anjer Point in Java, thrown up by the Krakatau tsunami, are of the same nature but less compact and with visible organic remains.
The biogeographical argument occupies the final section of the article. Ridley classifies the island’s plants according to their probable means of arrival: those whose seeds or fruits are carried unharmed by sea currents (e.g., Hibiscus tiliaceus, Inocarpus edulis, Barringtonia racemosa); those dispersed by fruit-eating birds and bats (e.g., Vitis, Leea, Randia, Ficus); those introduced accidentally by man near the settlements (e.g., Datura, Achyranthes aspera, Eleusine); and those carried by wind (e.g., Hoya Aldrichii, Blumea spectabilis). He addresses the apparent paradox of orchids being rare in oceanic islands despite their minute, wind-borne seeds, suggesting that epiphytic species may have arrived on fallen logs. Ferns, fungi, and mosses are attributed to the wide dispersal of their extremely light spores.
Key Findings
- The island measures approximately nine miles across, with a highest point of nearly 1,200 feet above sea level; the surrounding seas are very deep, offering few anchorage spots for large vessels (p. 124).
- Andrew Ross maintained a colony of 15 persons at Flying Fish Cove, cultivating coffee, coconuts, and vegetables in soil saturated with guano from the numerous nesting sea-birds (p. 124).
- Ridley described a new orchid, Saccolabium archytas, characterized by thick bright green leaves and long racemes of small white flowers spotted with pink, found in large masses on the island (pp. 126, 137).
- The endemic blue dove Carphophaga whartoni was noted as very abundant on the hilltop, extremely strong (several birds receiving four complete charges of shot before dropping), and successfully introduced by Ross to the Cocos Islands as an ornamental bird (p. 128).
- The giant land crab Birgus latro was described as “exceedingly abundant,” while no snakes were present on the island, though Ross had seen their skeletons washed up on shore (p. 129).
- The native palm Arenga Listeri (Becc.), about twenty feet tall with a stout green stem four inches through, produces a very excellent sago used as food by Ross’s party; its fruits are peculiarly irritating to the touch, like those of Caryota urens (pp. 127–128).
Conclusion
Ridley’s definitive historical takeaway is that the fauna and flora of Christmas Island is “typically Malayan” and “evidently primarily derived from the coasts of Java which is the nearest land.” He anticipates that further investigation of southern Java may reveal that some of the island’s peculiar endemic species also occur there, suggesting a closer biogeographical link than the island’s apparent isolation might imply.
Context
- Ridley wrote as a colonial-era scientific administrator (Director of the Singapore Botanic Gardens) conducting fieldwork in the Straits Settlements sphere; the article reflects the Victorian natural history tradition of documenting newly encountered islands for the benefit of metropolitan scientific societies.
- The study builds directly on the earlier collections of J. J. Lister (1888, HMS Egeria) and the taxonomic work of Hemsley and Rolfe, positioning Ridley’s brief visit as a corrective and supplement to those prior accounts.