The ultimate goal of the Mexican gray wolf Canis lupus baileyi captive management program is reintroduction of healthy individuals into wild habitats. To this end, zoo population managers work to provide not only for the physical well-being but also for the genetic health of these animals. However, the very limited genetic founder base, exacerbated by breeding within three distinct lineages, resulted in very high coefficients of inbreeding. Because support for measurable levels of inbreeding depression in the captive wolf population, as defined by reductions in common fitness measures such as juvenile survival or reproductive success, has been weak, we investigated the potential effects on male reproductive capacity. We analyzed semen samples from wolves from all three lineages and compared them with samples from subsequent lineage crosses and from generic gray wolves. We not only found a significant effect of inbreeding on sperm quality but we related both inbreeding and sperm quality to reproductive success. Samples from male offspring of lineage crosses, with inbreeding coefficients of zero were similar in quality to those from generic gray wolves. However, samples from a limited number of offspring from back-crosses were of extremely poor quality. Although it is reassuring that sperm quality was so much improved in male offspring of lineage crosses, the concomitant reduction in inbreeding coefficient does not eliminate the potentially deleterious alleles. Our results demonstrate that sperm quality is an important indicator of fertility and reproductive success in Mexican wolves. In addition, our data lend further support to the presence of inbreeding depression in this taxon.

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The volatile constituents of wolf anal-sac secretions were examined via capillary gas chromatography and compared among intact males, females, castrate males, ovariectomized females, and anosmic and pinealectomized males and females. Some chemical compounds were deemed significantly different (t test, 95% confidence level) among the groups both during and outside of the mating season, implying that the volatile components of anal-sac secretion can be used to communicate information regarding gender or endocrine state. As a result of treating the anal sac with antibiotics, some of these compounds, including 1-octen-3-ol and indole, were implicated as being products of microbial action. In addition, short-chain carboxylic acids were investigated and essentially no significant variations were seen among the groups.