Food supplementation leads to bottom-up and top-down food–host–parasite interactions

摘要: 1. Food-prey-predator interactions may involve both 'bottom-up' and 'top-down' processes. Conventionally, food-host-parasite have been seen as governed solely from the 'bottom-up', i.e. well-fed hosts can better resist parasites so suffer less parasitism. Recent studies on diverse endo- ecto-parasites increasingly highlight that provide with a resource base, be more likely to parasitized. 2. Brood exploit host parental behaviour by laying their eggs in others' nests. The brown-headed cowbird (Molothrus ater) is North American brood parasite exploits over 100 species. 3. We conducted food addition experiment song sparrows (Melospiza melodia), frequently parasitized host, near Victoria, BC, Canada. expected results consistent conventional effects because we previously found supplemented eluded nest predation, thus also them at eluding 4. Here, report contrary. Food were often non-food sparrows, multiply significantly often, suffered parasitism-induced egg loss. Our suggest cowbirds preferentially fed benefited doing fledged young per nest. pattern of loss accorded recent evidence indicating remove just right number maximize provisioning nestling. 5. work suggests parasitism vertebrates involves processes growing showing are complex than thought. One conservation implications our greater availability not respite parasitism, but is, nonetheless, beneficial overall.