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The Vital Statistics of an Unexploited Gray Squirrel Population
F. S. Barkalow, Jr., R. B. Hamilton and R. F. Soots, Jr.
The Journal of Wildlife Management
Vol. 34, No. 3 (Jul., 1970), pp. 489-500
Stable URL: http://www.jstor.org/stable/3798852
Page Count: 12
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The characteristics of an unexploited population of gray squirrels (Sciurus carolinensis) in North Carolina were studied over the period 1956-1964. The research area totalled 400 acres and was a part of a 5,200 acre continuous woodland. Density and survival information were obtained from an intensive tagging and recapturing program utilizing live traps and nest boxes. Life table and survival data were derived from the recapture records of 1,769 marked squirrels, 1,023 of which were of known age. Survival estimates are minimal because dispersal movements are included in mortality. An average annual dispersal rate of 14.5 percent is suggested. The mean value for survival during the first year was calculated as 0.26. No significant difference (P > 0.05) was detected between the recapture rates of spring and summer litters. The high rate of mortality (0.75) in the first year is counterbalanced by a high survival rate (0.52) in the adult categories. Adult females had a slightly higher survival rate than males (0.59 vs. 0.44). Mean life expectancy at birth was approximately 1 year (0.99). In the adult age groups the mean life expectancy increased from 1.82 years in the 1-2-year cohort to a high of 2.41 years in the 2-3-year cohort and remained above 1 year until the 7-8-year cohort when the mean life expectancy fell to 0.50 years. Cohort longevity was 6.4 years on a 99.5 percent turnover basis. Ecological longevity was about 9 years.
The Journal of Wildlife Management © 1970 Wiley