Scavenger

Scavengers are animals that consume dead organisms that have died from causes other than predation. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding behavior. Scavengers play an important role in the ecosystem by consuming dead animal and plant material. Decomposers and detritivores complete this process, by consuming the remains left by scavengers.Scavenger is an alteration of scavager, from Middle English skawager meaning 'customs collector', from skawage meaning 'customs', from Old North French escauwage meaning 'inspection', from schauwer meaning 'to inspect', of Germanic origin; akin to Old English scēawian and German schauen meaning 'to look at', and modern English 'show' (with semantic drift).Obligate scavenging is rare among vertebrates, due to the difficulty of finding enough carrion without expending too much energy. In vertebrates, only vultures and possibly some pterosaurs are obligate scavengers, as terrestrial soaring flyers are the only animals able to find enough carrion.Scavengers play a fundamental role in the environment through the removal of decaying organisms, serving as a natural sanitation service. While microscopic and invertebrate decomposers break down dead organisms into simple organic matter which are used by nearby autotrophs, scavengers help conserve energy and nutrients obtained from carrion within the upper trophic levels, and are able to disperse the energy and nutrients farther away from the site of the carrion than decomposers.Many species that scavenge face persecution globally. Vultures, in particular, have faced incredible persecution and threats by humans. Before its ban by regional governments in 2006, the veterinary drug Diclofenac has resulted in at least a 95% decline of Gyps vultures in Asia. Habitat loss and food shortage have contributed to the decline of vulture species in West Africa due to the growing human population and overhunting of vulture food sources, as well as changes in livestock husbandry. Poisoning certain predators to increase the number of game animals is still a common hunting practice in Europe and contributes to the poisoning of vultures when they consume the carcasses of poisoned predators.Highly efficient scavengers, also known as dominant or apex-scavengers, can have benefits to human well being. Increases in dominant scavenger populations, such as vultures, can reduce populations of smaller opportunistic scavengers, such as rats. These smaller scavengers are often pests and disease vectors.In the 1970s Lewis Binford suggested that early humans primarily obtained meat via scavenging, not through hunting. In 2010, Dennis Bramble and Daniel Lieberman proposed that early carnivorous human ancestors subsequently developed long-distance running behaviors which improved the ability to scavenge and hunt: they could reach scavenging sites more quickly and also pursue a single animal until it could be safely killed at close range due to exhaustion and hyperthermia.White-backed vultures feeding on a carcass of a wildebeestA jungle crow feeding on a small dead sharkCoyote feeding on an elk carcass in winter in Lamar Valley, near Yellowstone National ParkA polar bear scavenging on a narwhal carcassAn Ibiza wall lizard scavenging on fish scraps left over from another predatorRed weaver ants feeding on a dead giant African snail