In 2007, Festus Ihwagi completed a study on “Forage quality and Bark utilization by the African elephants (Loxodonta africana) in Samburu and Buffalo Springs national Reserves, Kenya”.

His full thesis and a journal publication article are available on the publications page.  

Abstract:

Foraging behavior of elephants with respect to debarking of woody species was investigated in Samburu and Buffalo Springs National Reserves, Kenya. Acacia elatior was the most preferred species followed by Acacia tortilis. Both A. elatior and A. tortilis dominate the woody vegetation accounting for over 80% of all woody plants. Debarking levels varied in different parts of the reserves and this was attributed to elephants’ densities and the ultimate influence of endaphic factors on species assemblages. Species diversity indices were negatively correlated with salinity indicating a direct influence of salinity on plant community structure. Both Acacia tortilis and A. elatior have the highest tolerance to salinity and occur almost exclusively in saline areas. Debarking was highest during the dry months just before the rains.

Through chemical analysis of bark samples collected from trees utilized at various intensities, the influence of bark mineral content on elephant’s debarking behavior was assessed. Samples were analysed for Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg), Sodium (Na), Iron (Fe), Manganese (Mn), Zinc (Zn) and Copper (Cu). The most preferred and abundant species, A. elatior had significantly higher nutrient elements than A. tortilis, the second most abundant. Debarking was positively correlated with levels of N, P, K, and Zn. Of these, crude protein (N) had the greatest influence on debarking behavior. Soil samples were collected in the sites and analyzed for physical properties and content of the above elements as well. Site differences in soil mineralogical content influenced bark nutrient content significantly in this study as there was significant positive correlation between nutrient content in bark and in soil samples from each plot. Phosphorus content was found to be high in soil but remarkably low in bark despite its significant correlation with debarking behavior. Aridity of the area, high soil pH and coarse soil texture contributed to generally low nutrient content of soil and subsequent unavailability of the nutrients to plants.   

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