Factors influencing timing of puberty in Mexican gray wolves (Canis lupus baileyi)

Abstract

Abstract The reintroduced population of Mexican gray wolves (Canis lupus baileyi) continues to rely on a carefully managed captive breeding program. Although success of that program depends on detailed knowledge of reproductive processes, age of puberty has not been determined. This study assessed male puberty status (presence of sperm in ejaculates), maintained in nine US facilities, during their first breeding season. Variables possibly associated with puberty were also evaluated. There was a significant effect of body weight, testis size, facility latitude, and date of collection, whereas a statistical trend was found for age and inbreeding coefficient. Social factors, including being housed with sire, had no effect. Over half the males in their first breeding season were producing sperm, although in some cases sperm quality was poor, suggesting possible infertility. Although there was no minimum body weight associated with presence of sperm, likelihood increased with increasing body weight, highlighting a possible critical role for nutrition. The trend for sperm production in males collected later in the breeding season and at lower latitudes suggests that later collections, especially at higher latitudes, might reveal a higher percentage of pubertal males. These results have potential implications for breeding program management and introduce the possibility that more wild gray wolves than previously thought might produce sperm during their first year, even if they do not sire young.