Fox Squirrels and Gray Squirrels in Illinois

Abstract

The project had two main objectives: 1. Determination of squirrel breeding seasons and related biology, the information derived to be used in recommending biologically sound squirrel hunting seasons. 2. Determination of the environmental requirements of Illinois squirrels, the information on this subject to be used in management and restoration practices. Field work covered a 4-year period, 1940-1943. No completely satisfactory census technique was developed. The western fox squirrel (Sciurus niger rufiventris) inhabits most wooded areas, including small woodlots and hedgerows, in every Illinois county. The gray squirrel (S. carolinensis leucotis and/or 5. c. carolinensis) occurs in all Illinois counties except some on the black prairie.  It is confined to dense forest stands and is most numerous in those with brushy understory in the river bluffs and bottoms areas. The red squirrel (Tamiasciurus hudsonicus loquax) was not found in Illinois by the writers.  Both fox and gray squirrels have two breeding seasons per year, the first in winter and spring and the second in spring and summer.  Second-season litters appear to be confined largely to vigorous females over 18 months old. Both spring-born and summer-born animals attain sexual maturity at the age of about 10 to 12 months, and the females produce their first young when approximately a year old.