Effects of male trophy hunting on female carnivore population growth and persistence

• Published in: Biological conservation Vol. 167; pp. 69 - 75
• Main Authors: Wielgus, Robert B., Morrison, Dana Eleanor, Cooley, Hilary S., Maletzke, Ben
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-11-2013; Elsevier
• Subjects: Additive mortality; Additives; Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; carnivores; Compensatory mortality; Conservation, protection and management of environment and wildlife; Cougars; Death; Demecology; demographic statistics; Demographics; Depensatory mortality; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Females; fish; Fundamental and applied biological sciences. Psychology; General aspects; Hunting; immigration; kittens; Males; Mortality; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Population growth; Puma concolor; reproduction; Survival; Ursus; wildlife; USA, Washington; Cougars; Hunting; Population growth; Compensatory mortality; Depensatory mortality; Additive mortality; Fissipedia; Carnivora; Mortality; Male; Trophic status; Carnivorous animal; Felis concolor; Persistence; Vertebrata; Additive; Mammalia; Female; Environmental protection
• ISSN: 0006-3207; 1873-2917
• DOI: 10.1016/j.biocon.2013.07.008

Carnivore populations are often managed based on the density dependent, compensatory mortality model, which suggests that trophy hunting of males causes an increase in female reproductive success, survival, and population growth. Our previous research on grizzly bears (Ursus acrtos) and cougars (Puma concolor) showed that increased mortality of males resulted in no net reduction in males due to increased immigration. Female reproduction and survival did not increase with male mortality. That research suggested that female demographics are additive to male mortality and might even be depensatory (inversely compensatory), whereby increased male immigration and infanticide may be associated with decreased female reproductive success, survival, and population growth. In this paper we test the compensatory, additive, and depensatory hypotheses by censoring female hunting deaths and plausible kitten infanticides from two independent cougar populations. The previously observed lack of compensatory demographics allowed us to censor deaths in this manner. The lightly hunted population (male hunting mortality=0.16) had a female population growth rate of 1.05. With female mortality from hunting removed the growth rate increased to 1.14. The heavily hunted population (male hunting mortality=0.35) had a female population growth rate of 0.78. With infanticide removed the growth rate increased to 0.89. With hunting mortality of females removed, the growth rate increased to 0.98. With both female mortalities and infanticide removed, the growth rate increased to 1.14. Light hunting of males (no net male immigration) decreased female population growth in an additive manner and heavy hunting of males (increased net male immigration) decreased female population growth in a depensatory manner. We reject the compensatory mortality hypothesis, and suggest that hunting of male carnivores has a negative additive or depensatory effect on female population growth depending on the intensity of male mortality. We recommend that hunting of polygnous carnivores not exceed their intrinsic growth rates to forestall excessive compensatory male immigration and infanticide. The Washington Department of Fish and Wildlife instituted a new “equilibrium” hunting management plan (hunting mortality<14%/year) for cougars in 2013 based on our findings and recommendations.