Statistical Analysis of Secondary Sex Ratio Variation in Sable Martes zibellina L.

The secondary sex ratio in sable Martes zibellina L. maintained in captivity was estimated for the first time ever. The data obtained at the Pushkin pedigree breeding farm (Moscow oblast) in 1982 through 1987 were analyzed. In total, 1705 litters of 418 females were examined. The total frequency of male births (P^ was 0.527 ± 0.007; the 95% confidence interval of P^ (the probability of birth of a male) was within the limits 0.513 ≪ p ≪ 0.541, and the deviation from the expected 1 : 1 ratio was statistically significant. No effect of parental age and litter size on the number of male progeny was found. This may indicate a small influence of the parental hormonal and immunological status on sex ratio, which was reported in many other mammal species including those related to sable. Apparently, there is an evolutionary mechanism underlying the stable excess of males in sable litters.