Elephant Loxodonta africana driven woodland conversion to shrubland improves dry-season browse availability for impalas Aepyceros melampus
Lucas P. Rutina, Stein R. Moe & Jon E. Swenson
Rutina, L.P., Moe, S.R. & Swenson, J.E. 2005: Elephant Loxodonta africana driven woodland conversion to shrubland improves dry-season browse availability for impalas Aepyceros melampus. - Wildl. Biol. 11: 207-213.
Along the Chobe Riverfront in northern Botswana, elephants Loxodonta africana have reduced woodland cover and modified woody species composition, forming shrublands. We tested the hypothesis that this has favoured the impala Aepyceros melampus population and contributed to the observed population increase by creating more available dry-season browse. Our results suggest that the increasing Capparis shrubland represents a key browsing habitat. The mixed Combretum shrubland was a less important browsing habitat, as female impalas browsed proportionally to the time spent feeding, but this habitat has more than doubled in extent, to almost 60% since 1962, thus providing much more available browse. The Baikiaea woodland, which has declined to less than half of its extent during 1962-1998 mainly due to elephant impacts, provided the least amount of dry-season browse for impalas. Impalas browsed mostly below 70 cm and conversion of woodland to shrubland has increased the availability of browse at this height. Our study suggests a three-way ecological interaction, with elephants changing the vegetation, and impalas increasing in number due to greater food availability.
Key words: Botswana, browsing ecology, habitat modification, savanna woodland
Lucas P. Rutina, Department of Wildlife & National Parks, P.O. Box 17, Kasane, Botswana & Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences - e-mail: lucasrutina@hotmail.com Stein R. Moe & Jon E. Swenson, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, N-1432, Ås, Norway - e-mail addresses: stein.moe@umb.no (Stein R. Moe); jon.swenson@umb.no (Jon E. Swenson)
Corresponding author: Lucas P. Rutina
Received 10 October 2003, accepted 1 May 2004
Associate Editor: Simon Thirgood