. The Canadian field-naturalist. 1980 ROLLEY AND KEITH: MOOSE. ROCHESTER, ALBERTA 13 # LONE ADULTS O COWS WITH CALVES. ^NOV KILOMETERS Figure 5. Mean monthly distribution of lone Moose and cows with calves during winters 1965-66 through 1978-79 at Rochester, Alberta. Origin was deter- mined as the mean location of all observations. seven years the mean number of adults on the survey area in late winter was to times that present in early winter. This increase in adult numbers was due to a seasonal movement from the muskegs on the east to the uplands on the west (Figure 5). Direct eviden
. The Canadian field-naturalist. 1980 ROLLEY AND KEITH: MOOSE. ROCHESTER, ALBERTA 13 # LONE ADULTS O COWS WITH CALVES. ^NOV KILOMETERS Figure 5. Mean monthly distribution of lone Moose and cows with calves during winters 1965-66 through 1978-79 at Rochester, Alberta. Origin was deter- mined as the mean location of all observations. seven years the mean number of adults on the survey area in late winter was to times that present in early winter. This increase in adult numbers was due to a seasonal movement from the muskegs on the east to the uplands on the west (Figure 5). Direct evidence of this shift in distribution came from tracking radio- collared Moose (Mytton and Keith, unpublished data). Productivity Mean calf-cow ratios (106:100) and twinning rates (41%) observed in winter at Rochester (Table 4) were the highest yet recorded, and also exceeded most reported in utero and during summer (Table 5). These rates indicated consistently high reproduction and early calf survival; the former was undoubtedly due to abundant browse supplies (Blood 1974; Markgren 1974), the latter was associated with an absence of Gray Wolves {Canis lupus) and scarcity of Black Bears {Ursus americanus). There were significant yearly differences in both percent of cows with calves and in twinning rates when we tested by chi-square, but these two statistics were Table 4—Percent of cows with calves, twinning rates, and calf-cow ratios of Moose at Rochester, Alberta, during win- ter helicopter transects. Number of cows and calf-cow groups are shown in parentheses % cows % calf-cow groups Calves per Winters with calves with twin calves 100 cows 1965-66 through 1969-70 60 (20) 58 (12) 105 1970-71 88 (25) 59 (22) 140 1971-72 59 (27) 31 (16) 78 1972-73 72 (93) 31 (67) 98 1973-74 70 (50) 46 (35) 106 1974-75 100 (24) 46 (24) 146 1975-76 90 (64) 38 (58) 100 1976-77 53 (32) 41 (17) 88 1978-79 70 (46) 17 (32) 89 Unweightec means (±SD) 74 (± 16) 41 (± 13) 106 (±23) Tables—Comparison of
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