Age-Related Reproduction in Striped Skunks (Mephitis mephitis) in the Upper Midwest

Abstract

Reproductive data from the upper Midwest are meager for the striped skunk (Mephitis mephitis), a common North American carnivore. We provide data on some age-related reproductive attributes of 178 female striped skunks collected at 19 sites in eastcentral North Dakota and westcentral Minnesota in 1979–1981 and 1987–1991. Seventy-four percent of the females were 1 year old; 95% were pregnant or parous when collected. Thirteen of 873 (1.5%) embryos in 123 pregnant females were being resorbed. The overall mean (±1 SE) litter size estimated from live embryos was 7.2 ± 0.4. Means of litter-size estimates were similar for females ≥1 year old, but annual estimates of litter size differed among years for all females combined. For females from the interval 1979–1981 and 1990, the mean implantation date based on embryo size was 4 March (±1.6 days). Potential litters were composed of a mean of 55 ± 3% females. Estimates of litter size based on counts of corpora lutea averaged 0.9 young per female less than estimates for the same females based on counts of live embryos, indicating that some skunks may have produced polyovular follicles or identical twins.