Phelsuma 18 (2010); 38-69 The timing of arrival of humans and their commensal animals on Western Indian Ocean oceanic islands. Anthony Cheke 139 Hurst St., Oxford OX4 1HE, UK
[email protected] Abstract: The principal island groups, Comoros, Mascarenes, and granitic Seychelles were first settled by humans at very disparate times: The Comoros during the 8th century CE, the Mascarenes from 1638, and the Seychelles not until 1770. As the settlers in the Comoros did not chronicle their lives, evidence of commensal arrival relies on archaeology, and there is no useful historical information on these animals until Europeans began visiting in the 1500s. By contrast in the Mascarenes, although ship rats preceded the first Dutch visit in 1598, Europeans documented their releases of livestock (various ungulates) on Mauritius and Réunion in the early 1600s, and the arrival (deliberate or not) of many other species thereafter. Releases were later, not until the 1730s, in Rodrigues (though rats were there by 1691). Cats arrived in the 1680s on the larger two islands, but Norway rats not until the 1730s. In the Seychelles ship rats were present in 1773, but their arrival date is uncertain; ungulates have been feral at various times, but are now longer so. Various other commensal or human food-related mammal, bird and reptile species are now present on many of the islands. In the Mascarenes particular waves of extinctions can be related to colonisation by specific introduced mammals. The low coral islands of the area have very disparate human and feral animal histories; details are given for the Aldabra group, the only low islands with significant endemism.