Mechanisms of species coexistence of optimal foragers: temporal partitioning by two species of sand dune gerbils

Applies a mechanistic approach to a sand dune community containing Gerbillus allenbyi and G. pyramidum. Previous work suggested that coexistence is based on temporal variability in seed resource density on a daily time scale and a tradeoff of foraging efficiency at high versus low resource abundances. Resource patches are depleted gradually throughout the night, a necessary assumption for temporal partition to allow coexistence. The first forage in a resource patch and the average forage for G. pyramidum is significantly earlier in the night than for G. allenbyi, and the last forage for G. allenbyi is significantly later than for G. pyramidum. G. pyramidum visits more patches earlier in the night than does G. allenbyi and its intensity of patch use based on sand tracking scores is also greater earlier in the night. Average resource patch visited by G. pyramidum is richer than that visited by G. allenbyi. G. pyramidum is thus profiting most from patches when resource densities are high, and it biases its foraging towards those times. -from Authors