Reproduction of the Marsh Rabbit (Sylvilagus palustris) in South Florida

Abstract

Reproduction of marsh rabbits (Sylvilagus palustris) in sugarcane in the vicinity of Belle Glade, Florida, was studied from September 1968 through August 1969. Rabbits more than 9 months old were considered to be the reproductive segment of the population. Pregnant females were collected throughout the year; however, a definite cycle was evident in pregnancy rates with increasing or high reproduction from December through June. Anestrous females were found during all months. Mean female reproductive characteristics were as follows: ovulation rate, 3.09 ova per pregnancy; preimplantation loss, 0.23 ova per litter; partial litter resorption, 0.09 embryos per litter; implantation rate, 2.82 embryos per pregnancy; estimated potential annual productivity, 14 to 19 young per female. Total litter resorption was observed in only two females. Testes weights and the diameter of seminiferous tubules showed a definite seasonal cycle similar to, but preceding by about 1 month, the female breeding cycle. Males judged fertile were present in all months. Mean reproductive characteristics of 12 parous juvenile (6 to 9 months old) females were as follows: ovulation rate 2.73, ovum loss 0.44, and implantation rate 2.40. Most juvenile males were judged to be fertile from December through May.