Factors Affecting Reproduction in the Red Wolf (Canis rufus).


The endangered red wolf (Canis rufus) was preserved in captivity with just 14 founders following its planned extirpation in the wild. Longitudinal reproductive events were investigated to determine whether inbreeding, parental age, and breeding experience were factors in reproductive performance and fitness. A behavioral preference study using olfactory presentations of conspecific and congeneric social odors also was conducted to determine those factors that are important in the selection of mates. Over 30 years of managed breeding, the level of inbreeding in the captive population has increased, and litter size has declined. Inbreeding levels were lower in sires and dams that reproduced than in those that did not reproduce, but there was no difference in the level of inbreeding of actual and predicted litters. Litter size was negatively affected by offspring and paternal levels of inbreeding, but the effect of inbreeding on offspring survival was restricted to a positive influence. Younger wolves were more likely to reproduce, and were more likely to produce larger litters, than were older individuals. The age of the dam, but not the sire, had a significant negative effect on pup survival. Sires and dams that had prior experience in the production of offspring were more likely to reproduce again than were individuals without prior reproductive success, but prior sexual experience alone was not a factor in the production of offspring. Parental breeding experience had a significant negative effect on pup survival, but no apparent relationships with size or sex ratio of the litter. In general, females responded to the presentation of social odors of conspecific males more quickly than did males, and males responded more quickly to social odors of conspecific females than did females. There were no differences in the proportion of time males and females spent proximal to conspecific social odors. Males and females typically responded more quickly to and spent more time investigating social odors during the non-breeding season than during the breeding season. Species-specific responses to social odors were indeterminate.



social odors, fitness, reproductive performance, breeding experience, age, inbreeding, red wolf, Canis rufus