Weather and the Harvest of Cottontails in New Jersey

Abstract

Correlations between harvest of cottontails (Sylvilagus floridanus) and weather variables during the breeding season were examined. The harvest variable was a standardized measure of the number of rabbits killed/hunter on selected public hunting areas of New Jersey on the opening day of small-game season. Weather variables included measures of rainfall and temperature during the previous breeding season. Multiple regression analysis indicated two rainfall variables significantly related to harvest: (1) the summation of March and September rainfall was highly significant (F1, 4-= 24.79; r' = 0.36) and probably reflected the importance to the fall harvest of first-litter survival coupled with survival of young produced by the breeding of first-litter survivors, and (2) April through August rainfall contributed to the model in an additive manner. The number of months during this period with 12.5 cm or more of rainfall was significantly related to harvest (F2,, 1 = 3.80) and accounted for an additional 4 percent of variability in opening-day harvest. J. WILDL. MANAGE. 40(4):658-662 The harvest of cottontail rabbits can vary a great deal from year to year (Wight 1959). This variability frequently is attributed to the effect of weather on breeding success during the previous season (Smith 1966:366), but a survey of the literature revealed no studies that have identified quantitative variables with predictive value. Meslow and Keith (1971) demonstrated a relationship between juvenile mortality and weather variables in snowshoe hares ( Lepus americanus), but such a relationship has not been demonstrated for cottontails. Life tables for cottontails (Lord 1963:79), however, indicate that 75 percent of rabbit mortality occurs within the first 4 months of life, suggesting that factors affecting juvenile survival would have a significant effect on the population and subsequent harvest of cottontails. The cottontail rabbit begins breeding in late February or early March, with the first litter generally born in March (Conaway and Wight 1962). Subsequent litters are produced at approximately monthly intervals throughout the summer, owing to a postpartum estrus and 28-day gestation period (Casteel 1967); the last litter usually is born in late August or early September (Lord 1963). The occurrence of juvenile breeding in the cottontail is well documented (Negus 1959, Lord 1963, Casteel and Edwards 1964), and the importance of juvenile breeding to the fall harvest has been postulated (Lord 1958, 1963). Kibbe and Kirkpatrick (1971) suggested that most juvenile breeding may involve only first-litter juveniles. The relative survival of this first litter thus has the potential of contributing exponentially to the fall rabbit population, whereas success of all other litters contributes only in an additive man-