Giant tortoise and vegetation interactions on aldabra atoll—Part 1: Inland

• Published in: Biological conservation Vol. 9; no. 4; pp. 293 - 304
• Main Authors: Merton, L.F.H., Bourn, D.M., Hnatiuk, R.J.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 1976
• ISSN: 0006-3207
• DOI: 10.1016/0006-3207(76)90051-3

A very large endemic population of giant land tortoises, which are the major terrestrial herbivores, survives on the western Indian Ocean atoll of Aldabra. Tortoise densities are highest in the inland areas of the south-east where the habitat is being greatly modified by tortoise activity. In particular, they are responsible for considerable soil erosion and the death of many trees and shrubs with the resultant reduction in the amount of shade cover, which is so important to tortoise survival. There are also signs that food resources may be limiting: the low vegetation is intensively cropped; there are pronounced browse lines on most tree species and tortoise growth rates are reduced. A reduction in tortoise numbers is therefore a distinct possibility.