. The Canadian field-naturalist. 1987 TESTER: ACTIVITY RHYTHMS OF ANIMALS 15 24:00 18:00-. FEB MAR APR MAY JUN JUL AUG SEP Figure I. Seasonal activity patterns for Gray Squirrels from July 1971 to September 1972 (average for 4-8 squirrels). Full width of each period indicates 100% activity. The curved horizontal lines show sunrise and sunset. Time is Central Standard Time. MuSKRAT, Ondatra zibethicus In general, Muskrats are considered to be nocturnal. However, O'Neil (1949) and Errington (1963) suggested that high population density and/or certain meteorological conditions might result in inc
. The Canadian field-naturalist. 1987 TESTER: ACTIVITY RHYTHMS OF ANIMALS 15 24:00 18:00-. FEB MAR APR MAY JUN JUL AUG SEP Figure I. Seasonal activity patterns for Gray Squirrels from July 1971 to September 1972 (average for 4-8 squirrels). Full width of each period indicates 100% activity. The curved horizontal lines show sunrise and sunset. Time is Central Standard Time. MuSKRAT, Ondatra zibethicus In general, Muskrats are considered to be nocturnal. However, O'Neil (1949) and Errington (1963) suggested that high population density and/or certain meteorological conditions might result in increased diurnal activity. Van Horn (1975) reported an increase in diurnal activity after ice formed on his study lake in Wisconsin. Using data from tracks in sand transects, Stewart and Bider (1977) reported that Muskrats had a bimodal waveform with peaks occurring about 1630 h and 2230 h. Muskrats at Cedar Creek exhibited an activity rhythm quite different from that of Gray Squirrels and Red Foxes. During the period of study, from July 1969 through February 1970, the number of activity periods per 24 hours varied from two to four. From July through about 30 August, four periods of activity were about evenly distributed throughout the 24 hours. In subsequent months the number of activity periods was reduced to three and then to two. In this reduction, which occurred at the time of freeze-up of lakes and streams, the day activity periods were eliminated and Muskrats became essentially nocturnal (Figure 5). Unlike the Red Fox, the total. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ottawa Field-Naturalists' Club. Ottawa, Ottawa Field-Naturalists' Club
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