AGE-RELATED REPRODUCTION IN STRIPED SKUNKS (MEPHITIS-MEPHITIS) IN THEUPPER MIDWEST

Reproductive data from the upper Midwest are meager for the striped sk unk (Mephitis mephitis), a common North American carnivore. We provide data on some age-related reproductive attributes of 178 female stripe d skunks collected at 19 sites in eastcentral North Dakota and westcen tral 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 reso rbed. The overall mean (+/- 1 SE) litter size estimated from live embr yos was 7.2 +/- 0.4. Means of litter-size estimates were similar for f emales greater-than-or-equal-to 1 year old, but annual estimates of li tter size differed among years for all females combined. For females f rom the interval 1979-1981 and 1990, the mean implantation date based on embryo size was 4 March (+/- 1.6 days). Potential litters were comp osed 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 estim ates for the same females based on counts of live embryos, indicating that some skunks may have produced polyovular follicles or identical t wins.