SOME ASPECTS OF REPRODUCTIVE-PERFORMANCE IN FEMALE RED FOX IN NORTH-DAKOTA

Female age class and spring adult sex ratios consistently affected (P < 0.05) reproductive performance of North Dakota red fox (V. vulpes). Reproductive performance increased through 8 age classes. Increases (P < 0.05) in ovulation rates, embryonic litter sizes and declines in prenatal mortality were observed as a function of increasing female age. Body fat was found to increase in relation to female age class. An inverse relationship was noted between annual estimates of ovulation rates compared to March adult sex ratios and embryonic litter size compared to March adult sex ratios. A direct relationship was determined for annual estimates of prenatal mortality and March adult sex ratios. No consistent relationship was found between annual estimates of ovulation rates, embryonic litter sizes or prenatal mortality when compared to annual spring population density.