Ecological communities can be envisioned as collections of species that are organized into food chains and webs in which each species is a consumer of resources and is itself a resource for other consumers. Ecologists call these consumptive interactions trophic interactions. And so, species engaging in a particular kind of trophic interaction are said to belong to a distinct trophic group. Ecologists routinely idealize food chains and webs as being comprised of four trophic groups. Species that consume mineralized nutrients and CO2 in order to photosynthesize carbohydrates belong to the plant trophic group, species that consume living plant tissue belong to the herbivore trophic group, species that prey on herbivores belong to the carnivore trophic group, and species that recycle dead organic material back into the nutrient pool belong to the decomposer trophic group.
Such classic idealization of ecological systems typically ignores another trophic group, scavengers. After all, mobs of bloody headed vultures vying for their share of a carcass or insect larvae crawling in stinking, rotting meat do not engender the same sense of awe and natural wonder as do grazing antelope and lions coexisting on the Serengeti plains of Africa. Scavengers get short shrift in ecological thinking because their role is typically viewed as being a repulsive behavioral curiosity or the ecological equivalent of garbage men that sustain themselves on nature's offals. Scavengers are sometimes viewed merely as parasites that steal food - called kleptoparasitism -from the more noble carnivores. These are, however, unfortunate and inaccurate characterizations of scavenging. As we will show below, scavenging serves an important role to the welfare of many species and it can be an important determinant of the structure and functioning of ecological communities. Moreover, scavenging involves many more species than those few specialists that are routinely highlighted as serving this role.
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