"Although food exploitation is influential in predisposing carnivores to attack each other, relative body size of the opponents appears to be overwhelmingly important," write the authors.
In theory, explain the authors, carnivore species of similar body size would be most likely to compete for similar prey, increasing the likelihood of lethal encounters. However, they found that attacks from carnivores on other carnivores were most frequent when body sizes were moderately different and diet overlap extensive.
When the difference in body size was small, they were less likely to attack, no matter how much the diet of the two species overlapped, because the risks of an attack were high.
When the difference in body size was intermediate, then the larger species of carnivore was much more willing to attack and kill the smaller carnivore species. Explain the authors, "The larger carnivore perceives the opponent as large enough to be a competitor, yet small enough to be defeated with low risk."
Founded in 1867, The American Naturalist is one of the world's most renowned, peer-reviewed publications in ecology, evolution, and population and integrative biology research. AN emphasizes sophisticated methodologies and innovative theoretical syntheses--all in an effort to advance the knowledge of organic evolution and other broad biological principles.
Donadio, Emiliano, and Steven W. Buskirk. "Diet, morphology, and interspecific killing in carnivora," The American Naturalist 167:4.