Aging impairs athletic performance. Human athletes are one example, but athletic senescence has also been documented in birds, fish, rodents, horses, and dogs. Whereas it is well established that athletic senescence hinders the ability of wild animals to escape from predators, surprisingly little is known about how aging affects the ability of predators to capture prey. Research into long-lived predators has generally assumed that adults have uniform impacts on prey regardless of age. We test this assumption with longitudinal data from repeated observations of 94 individually-known wolves (Canis lupus) hunting elk (Cervus elaphus) in Yellowstone National Park. 

Results/Conclusions

We found that ageing reduces wolf predatory performance as predicted by evolutionary theory, and that this drives an inverse relationship between prey offtake and the ratio of senescent hunters in the wolf population. Because this ratio fluctuates independently of population size, predatory senescence may cause populations of equal size but different age structure to have different impacts on prey. These findings suggest that predatory senescence is an important, yet largely overlooked factor affecting the impact of long-lived predators on prey populations.