Obligate vertebrate scavengers must be large soaring fliers

摘要: Among extant vertebrates, only the 23 species of vulture are obligate scavengers. We use an energetic modelling approach to explore constraints imposed by scavenging lifestyle, and ask whether scavengers must always be avian generally large-bodied users soaring flight. Our model found that aerial out-competed postulated terrestrial ones, mainly because flight allows area searched much more rapidly for carrion. Soaring was favoured over flapping reduction in speed (and so rate search) than compensated decrease costs transport. Large individual size is selected if carrion available large packages, when scavenger feed infrequently, able survive on body reserves periods between discovering food falls. In absence radiation, seems energetically feasible, but we argue such a beast unlikely have evolved. birds, order become exclusive scavengers, vultures needed specialize efficient as low energy form travel, consequence they lost agility kill prey. mammals, however, no comparable trade-off occurs. So carnivores there probably strong selection pressure towards being scavenger. Indeed it will perhaps advantageous retain flexibility obtaining either predation or scavenging.