Orphans' tales: seasonal dietary changes in elephants from Tsavo National Park, Kenya

摘要

The similarity of μ~(13)C and μ~(15)N patterns in hairs of different individuals from the Tsavo East orphaned elephant herd indicates that a single hair represents the dietary preferences and behavior of the entire group. Multiple tail hairs from the same individual collected at different times allows a chronology to be established because of the overlap in isotope patterns in hair, and there is a very high correlation between hair from different individuals in the same group. Forward modeling using a three-component isotope turnover model for hair allows a precise estimate of diet of these elephants over a 2-year interval. Elephants from Tsavo East National Park in Kenya feed predominantly on C_3 leaves, although they have a significant fraction of C_4 grass in their diet for a short time at the beginning of the rainy season. The overall integrated diet for the elephants studied is between 10% and 15% C_4 grass, although it reaches up to 60% for short intervals. Stable carbon isotope analyses of elephant tooth enamel show that the average integrated dietary preference of elephants in Tsavo National Park remained less than 25% grass between 1940 and the present.