Print PageFew studies have looked at successional changes in food webs. One area this has been actively studied, however, is in the arthropod fauna of cow feces. Arthropods colonize fresh cow feces and utilize this resource for both larval rearing and as hunting grounds. Species diversity as well as trophic diversity can be quite high on cow patties and can undergo dramatic changes in as little as a few days. While the composition of senescing cow patties has been somewhat studied in temperate regions of the northern hemisphere, it has received little attention in the tropics. To address this discrepancy, I sampled the arthropod taxa within and among cow patties placed in both a grazed pasture and an intact forest site in Monteverde, Costa Rica over five days.
Results/Conclusions
The number and complexity of taxa found here as well as the interactions among them increased with time of exposure of the fecal resource for the first 72 to 96 hours. After this time, the resource senesced and trophic complexity decreased at both sites. Putative food webs constructed for pasture and forest sites showed higher trophic complexity in the forest site than in the pasture site. The forest was also more diverse and species even than was the pasture, the latter having been dominated by fly larvae. These results support the contention that intact forests are more diverse and complex than are human modified areas. These results also have potential importance for human health as disease-transmitting Muscid flies have significantly higher densities in pastures where their Staphylinid predators are significantly less abundant and food webs are less complex.
