Print PageBody size and other morphological traits play a fundamental role in the ability of animals to locate, capture, and handle different resources. For those species that live and forage in groups, relevant traits operating at the group level, such as foraging group size and level of cooperation, may also influence foraging ability and further shape the overall resource use by a species. For instance, larger groups containing a greater number of cooperating individuals may be able to capture larger prey than smaller groups with less cooperation. We explored the role of group living and cooperation in resource use in a social spider community where four congeneric species of similar body size, but with behaviours ranging from near-solitary to fully social, co-occur.
Results/Conclusions
We found that the range of insect sizes captured by each species reflected their nest and colony size so that species with larger colonies and prey capture webs captured larger insects than less social species. Yet, among those species whose webs did not differ significantly in size—the two with the largest and the two with the smallest webs—one captured significantly larger insects than the other. This difference may be due to differences in the extent to which nest mates cooperated in the capture of prey, as in only one of the species in each pair did the size of the insects captured increase with colony size. The four species were thus packed along the spectrum of available insect sizes from least to most social, with limited overlap between contiguous species. This pattern of resource use was more over-dispersed than expected by chance, as would be expected if the species had been assembled or differentiated to avoid extensive dietary overlap.
