Effects of a Common Environment on Cottontail Ovulation Rates

Abstract

Cot-tontails (Svlvilagus floridanus) from unglaciated southeastern (SE) Ohio and glaciated west-central (WC) Ohio were placed in four 5-acre pens on the Delware Wildlife Area in autumn, 1962. The following spring 141 were recovered from the pens and an additional 81 females were collected in the SE and WC regions to serve as controls. The objective of the experiment was to determine the effects of a common environment on the ovulation rates of cottontails from 2 populations that occur in dissimilar habitats and have different ovulation rates. There was no significant difference in the mean number of corpora lutea per doe between the SE (4.81) and the WC (5.00) experimental populations. There was a significant difference between the SE control (3.92) and each of the other 3 populations. The WC control population averaged 5.23 corpora lutea per doe. No relationship was found between paunched body weights and ovulation rates. It was concluded that ovulation rates of Ohio cottontails are controlled by the environment (probably physical rather than social) and not by genetic makeup and that both ovulation rates and paunched body weights of females in southeastern Ohio are significantly lower than those of females in west-central Ohio.