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Invasive Plants and Water Helped Shape Elephant Habitat Use in a Fenced Kenyan Reserve

African bush elephant standing in a river in Kenya
Research · Ecology

Researchers used the distribution of dung to examine seasonal habitat use by the African bush elephant (Loxodonta africana) in a small, enclosed Kenyan reserve. The study, published on 29 April 2026, linked dry-season patterns most strongly to the distribution of invasive plants, distance from permanent rivers and elevation. During the wet season, distance from the reserve boundary was the largest contributor to the model.

Mwea National Reserve covers 44 square kilometres in Embu County. An artificial fence forms one boundary, while the permanent Thiba and Tana rivers form others. The reserve has no migration corridors, so its growing elephant population must find seasonal food and water within a restricted area.

The field team surveyed 96 straight transects, each 250 metres long, with approximately 350-metre reconnaissance walks between them. Every dung pile seen along these routes was mapped and assigned to an age class. The combined dataset contained 2,540 dung locations from the dry season, July to October, and 1,345 from the wet season, November to January. The analysis excluded the oldest categories and used more recent dung as an indicator of where elephants had been.

The researchers modelled these locations against five variables: distance from the reserve boundary, elevation, invasive-plant distribution, distance from permanent rivers and the Normalized Difference Vegetation Index, or NDVI, a satellite-based measure of vegetation greenness. Higher NDVI values indicate greener, more productive vegetation and were used here as an indicator of forage conditions. The authors described both seasonal models as having fair predictive performance.

Seasonal drivers changed between dry and wet seasons

In the dry-season model, invasive-plant distribution contributed 28.9% of the prediction, distance from permanent rivers 26.9% and elevation 26.5%. NDVI contributed 16.2%, while boundary distance contributed 1.4%. The order changed in the wet season: boundary distance contributed 38.9%, followed by NDVI at 20.1%, invasive plants at 16.3%, elevation at 13.2% and river distance at 11.6%. These percentages describe how much each predictor contributed to the model, rather than the proportion of elephants using each habitat.

The mapped patterns placed more dry-season use near rivers and productive riparian vegetation. With rain and more widely available forage, the predicted wet-season range expanded towards central and higher parts of the reserve. The stronger boundary signal during the wet season was interpreted as evidence that physical barriers still constrained wider dispersal when water and food were less limiting.

Predicted elephant habitat use in the dry season (a) and wet season (b). Warmer colours indicate higher predicted use; each panel has its own scale.
Predicted elephant habitat use in the dry season (a) and wet season (b). Warmer colours indicate higher predicted use; each panel has its own scale. Wambua et al. (2026), Figure 4 / figur 4, CC BY 4.0.

Invasive plants overlapped with useful resources

Three invasive plants considered in the study were Parthenium hysterophorus, Senna didymobotrya and Senna spectabilis. Their patches overlapped with riverine sites that also provided water, shade and native forage. The authors stress that the elephants did not show a preference for invaded areas. Instead, invasive plants and useful resources occurred in some of the same places. The invasive species were not yet widespread, but could reduce native forage if they expand.

Management should protect dry-season resources

The researchers recommend protecting key dry-season water and feeding areas, maintaining varied vegetation and targeting invasive plants at important foraging sites. They also propose continued community cooperation, maintenance of the reserve boundary and periodic translocation to keep pressure within the small reserve manageable.

Sources and image credit

  1. Wambua, J. K., Wato, Y. A., Abdallah, S. A., Mworia, J. K., Lukhoba, C., & Gichuki, N. N. (2026). Determinants of seasonal elephant habitat use in small and enclosed conservation area: Mwea National Reserve, Kenya. Ecology and Evolution, 16(5), e73538.

Image: Mara 1 — African bush elephant in a Kenyan river, 26 February 2009. Representative photograph, not documented as taken in Mwea. Cropped to 16:9. Source: Wikimedia Commons. · CC BY 2.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

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