1Exceptionally high rates of tooth fracture in large Pleistocene carnivorans imply intensified 2 interspecific competition, given that tooth fracture rises with increased bone consumption, a 3 behavior that likely occurs when prey are difficult to acquire. To assess the link between prey 4 availability and dental attrition, we documented dental fracture rates over decades among three 5 well-studied populations of extant gray wolves that differed in prey:predator ratio and levels of 6 carcass utilization. When prey:predator ratios declined, kills were more fully consumed, and rates 7 of tooth fracture more than doubled. This supports tooth fracture frequency as a relative measure 8 of the difficulty of acquiring prey, and reveals a rapid response to diminished food levels in large 9 carnivores despite risks of infection and reduced fitness due to dental injuries. More broadly, large 10 carnivore tooth fracture frequency likely reflects energetic stress, an aspect of predator success 11 that is challenging to quantify in wild populations. 12 13 14