Crist and Wiens studied how seed harvesting by western harvester ants (Pogonomyrmex occidentalis) was different across spatial scales and organizational levels from individual ants to populations, and how vegetation structure affects foraging movements of individuals and resource use of colonies and populations. Lightly-grazed pastures with heterogeneous structure had the most seed removal on patches of bare ground. Areas in prairie dog (Cynomys ludovicianus) colonies had the least seeds removed, which is probably attributed to the presence of the harvester ant predator, the short-horned lizard (Phrynosoma douglassi), in these areas. Indian ricegrass (Oryzopsis hymenoides) and pepperweed (Lepidium densiflorum) comprised 91% of all seeds harvested, most taken from bare ground patches near ant nests. Seed removal was largely influenced by population level processes, including predation and grazing intensity.
Rangeland Ecology & Management
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