Abstract:
Trophy hunting plays a significant role in wildlife conservation in some contexts in various
parts of the world. Yet excessive hunting is contributing to species declines, especially for
large carnivores. Simulation models suggest that sustainable hunting of African lions may be
achieved by restricting offtakes to males old enough to have reared a cohort of offspring. We
tested and expanded criteria for an age-based approach for sustainably regulating lion
hunting. Using photos of 228 known-age males from ten sites across Africa, we measured
change in ten phenotypic traits with age and found four age classes with distinct
characteristics: 1-2.9 years, 3-4.9 years, 5-6.9 years, and ≥7 years. We tested the aging
accuracy of professional hunters and inexperienced observers before and after training on
aging. Before training, hunters accurately aged more lion photos (63%) than inexperienced
observers (48%); after training, both groups improved (67-69%). Hunters overestimated 22%
of lions <5 years as 5-6.9 years (unsustainable) but only 4% of lions <5 years as ≥7 years
(sustainable). Due to the lower aging error for males ≥7 years, we recommend 7 years as a
practical minimum age for hunting male lions. Results indicate that age-based hunting is
feasible for sustainably managing threatened and economically significant species such as the
lion, but must be guided by rigorous training, strict monitoring of compliance and error, and
conservative quotas. Our study furthermore demonstrates methods for identifying traits to age
individuals, information that is critical for estimating demographic parameters underlying
management and conservation of age-structured species.
