Elephant seasonal vegetation preferences across dry and wet savannas

The influence of increasing population size and vegetation productivity on elephant distribution in the Kruger National Park. Please acknowledge Kim Young, Salamon and Rudi van Aarde (19th march, 2009).

ABSTRACT

As African savanna elephants (Loxodonta africana) become increasingly confined to smaller fragmented landscapes, concern over their potential detrimental impacts on vegetation and biodiversity has increased.

Understanding elephant vegetation preferences across relevant spatial and temporal scales is a critical step towards managing protected areas for the persistence of both elephants and biodiversity. To better understand elephant vegetation selection, we fittted 68 elephants with GPS collars across a strong rainfall gradient spanning seven southern African countries over a period of 6 years. We compared elephant locations with remotely-sensed environmental data that measure bi-monthly vegetation green- ness across the study area.

Elephants consistently seek out greener than expected vegetation throughout the year. Interestingly, they do so by utilizing vegetation with different phenologies and by selecting landscapes when they are greener than their surroundings. We found no differences between dry and wet savannas. These patterns persist even when elephants are constrained by seasonally available water.

In the wet season, elephants select seasonally variable landscapes such as open woodlands, shrublands, and grasslands. These landscapes have a lower average annual greenness but become very green for a few months in the wet season. In the dry season, elephants prefer less variable landscapes that are more con- sistently green year-round such as well-wooded areas and closed woodlands. Because elephants prefer different vegetation types at different times of the year, small homogeneous protected areas may be unsuitable for elephants. Since elephants prefer woody vegetation during the dry season when they are constrained by water, human actions that increase dry season water availability may contribute to detrimental elephant impacts on vegetation and biodiversity.

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