Date of Award

12-1-1973

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Abstract

A study of the ecology and life history of the northern raccoon Procyon lotor hirtus Nelson and Goldman, 193C) was conducted ir. southwestern Manitoba between June, 1967, and August, 1969. Information concerning growth, development, reproduction and population characteristics was gathered from carcasses of 293 raccoons of juvenile, yearling, and adult age. Seasonal activities and home ranges were determined by marking 81 mobile raccoons and 13 nestlings, and by recaptures of 27 of these. Movements of 11 raccoons were monitored electronically, A total 1,109 scats and 298 stomachs and colons were analyzed for food content and to determine seasonal requirements of nutrition. Eighty-six dens were investigated to determine seasonal needs for protection. Body weights were compared with ages of 351 raccoons collected at various seasons, and with winter mortality. Winter denning activities were compared with ambient temperatures and with den quality to determine the effects of the winter environment on survival. Recent changes in the ecology of the aspen parklands, mortality factors, and limiting factors were investigated to determine the present status of raccoons in the northern part of their range.

Three age classes of raccoons were described, based on eye lens weight. Juveniles became yearlings at nine months when eye lens weight was 85 mg. Yearlings became adults at 15 months, when eye lens weight was 114 mg. Mating took place from late February to June, with the peak in activity in March; the peak of parturition occurred in May. However, 13.6$ of births were as late as the first week in September; these were attributed to malnutrition and disease in winter. Adults produced 4.1 young per female and yearlings produced 3.3; an average 2.5. This was an increase from a minimum spring breeding population of 3.9 per square mile to a total summer population of 8.4 per square mile. Only 26$ of the yearlings and 36.5$ of the adults produced litters; prenatal mortality was 67$ and 4$, respectively.

Home range and distribution of raccoons varied with sex and age, breeding behaviour, seasonal food availability, and denning requirements. Travel was infrequent in winter but was greatly increased during the spring mating period and ’when protein became available as ice thawed in potholes. Yearlings were found to disperse at that time. Females were restricted in their movements until litters became mobile. Activities were concentrated in tree bluffs when wild fruits were available in late summer and fall and stored grain was sought the year round. Winter dens in scrub piles, cellars, and burrows were replaced by spring breeding dens in scrub piles, attics, an'1 hay lofts, and these in turn by summer day beds in scrub piles and pothole edge vegetation.

Juvenile body weight decreased approximately 30$ over winter and yearling mortality rate was high, possibly 60$. Mortality rate for the entire population was greater than 50$. Mean life span was 1.3 years and turnover rate was 7.4 years.

The major limiting environmental factors were lack of food and denning sites in winter. These have been replaced in large part by stored grain, vacant farmsteads, and scrub p51es which have greatly increased in number since the 1940s, due to changes in agriculture and economic policies. Raccoons have become established in Manitoba and are presently increasing in the northern part of the aspen parklands.

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