Ecological History

Introduction

The Mascarenes are almost unique in terms of oceanic island ecological history as, upon their discovery by man, they were still comparatively intact and unaltered. Arab traders were aware of the islands from at least the thirteenth century, but no attempt at settlement in the Mascarenes was made. It was with the chance discovery by Vice-Admiral Wybrandt Warwijck in September 1598 that the documented history of the Mascarenes began. For the next half-century, references were made about the fauna and flora of Mauritius, but most were vague and inadequate. Rodrigues fared somewhat better with accounts by the Huguenot refugee, Francois Leguat in 1691-92 and by Tafforet in c.1726 being extremely detailed and accurate. Sieur Dubois stayed on Réunion Island from 1671-2 and provided the most detailed account of Réunion’s fauna, but as for Mauritius, most other accounts were gastronomically biased or too vague to be of much use to science.

The discovery of fossil material has allowed some corroboration of these early accounts; however, vagueness and inaccuracies often make it very difficult to decipher what the observers were trying to describe. Often too much emphasis has been placed on these descriptions and inevitably mistakes have occurred.

Oceanic islands provide excellent sources of data, particularly for phylogenetic study. Being isolated, they represent contained laboratories and the process of evolution, although probably not differing substantially from continental landmasses, is easier to comprehend. The Galapagos, Mascarenes, Hawaiian Archipelago, and the island groups of the South Pacific and New Zealand, to name but a few, epitomise oceanic island ecosystems but sadly also exhibit their vulnerability to anthropogenic changes.

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The Mascarenes: A history of palaeontological research.

Mauritius

The palaeontological history of Mauritius began with the discovery of fossil material in a marshy deposit known as the Mare aux Songes in southeast Mauritius by George Clark and railway engineer Harry Higginson. Prior to 1865, Strickland and Melville produced a seminal monograph on the dodo in 1848 whilst lacking adequate skeletal evidence. In 1865 Clark, after a tip-off from Higginson, chanced upon the marsh and discovered vast quantities of skeletal material – sugar cane workers were employed to wade into the deepest areas of the marsh and feel for specimens with their hands and feet – that were subsequently sent to London and Cambridge for study. From these remains, species such as the Dodo Raphus cucullatus, were scientifically described. In 1879, a government commission was set up to excavate the site from which further bird and reptile species were described based on subfossil material.  At the end of the 19th century, Paul Carié and Etienne Thirioux, two amateur naturalists, reworked the Mare aux Songes and also collected from cave deposits, the exact locations of which remain unknown. This resulted in complete skeletal specimens of some of the extinct fauna including numerous examples of the dodo. Rothschild, an enthusiastic ornithologist, erected extinct Mascarene species based on historical accounts, but his approach was rather eccentric and he confused the provenance of some of the descriptions. Little further research was undertaken on the extinct Mascarene fauna until Hachisuka produced his work in 1953, however, he succeeded only in confusing rather than clarifying the situation. Holyoak re-examined the Mauritian parrot material describing a new species in the early 1970s, whilst Cheke, in 1987, provided a complete historical review of the ecology and Cowles discussed the fossil history. An expanded and up to date ecological history was produced by Hume and Cheke in 2008.

Réunion

The fossil record of Réunion Island escaped scientific attention until the 1970s when B. Kervazo excavated cave deposits on the north-west side of Réunion. During the 1980s, four new fossil localities were discovered by Mourer-Chauviré and her co-workers, which helped resolve many of the taxonomic problems concerned with species hitherto known only from rather inadequate travellers’ accounts. Unfortunately all four localities are situated in areas deemed suitable for development and all are under threat of destruction.

Rodrigues

Although the first Rodrigues fossil material had been collected in 1786, the specimens were not described until 1848. It was during the 1870s that major excavations of the caverns on Rodrigues ensued, particularly by the local magistrate George Jenner, and produced many thousands of bones, most in excellent condition. The early accounts of Leguat 1691-2 and Tafforet c.1726, which describe the fauna in some detail, accord with subsequently discovered fossil material; in particular, in providing evidence for a second species of didine, the solitaire Pezophaps solitaria. Cowles mentioned 2 new species (including 1 new genus) of passerine and a possibly extinct Pterodroma petrel, but these still remain undescribed. All fossil material was found in a limestone deposit, the Plaine Corail, situated on the southwest corner of the island.

  • Copyright © 2010 Julian Hume. All rights reserved.