Dynamics of Moose Populations in Northeastern Alberta

Publisher Website
Google Scholar
Abstract
Intensive studies of moose (Alces alces) were conducted on a 25,000 km2 study area in northeastern Alberta from Jan. 1976 to June 1978. Moose (66) were radio-collared and color-marked and another 8 were color-marked only. The population was either stationary or slowly declining; an estimate of 4595 (0.18/km2) was obtained for the entire study area in winter 1977-1978. The proportion of yearlings in the population increased between winter 1975-1976 and 1976-1977, the result of higher reproduction and/or calf survival in 1975-1976. The best estimate of the combined yearling and adult sex ratio was 30:70. There was an inverse relationship (r2 = 0.62) between age of radio-collared bulls and dates of antler drop. Calf production as indexed by calf-cow ratios was similar in spring (May-June) 1976 and 1978, but fall ratios were higher in 1977 than 1976. Calves constituted 30% of the 1975-76 winter population, 18% in 1976-77 and 20% in 1977-78. The annual survival rate of calves of radio-collared cows was 0.27. Survival of calves was lowest in the 1st month of life (0.61) and rose in subsequent months (0.95). An estimated 29% of calf losses were due to wolf (canis lupus) and predation. The annual survival rate of radio-collared yearlings and adults averaged 0.75. A 2nd estimate of 0.76-0.77 was obtained independently from demographic and kill data for the entire study-area population in 1977-1978. Hunting and wolf predation were the main causes of mortality among yearlings and adults: wolves consumed an estimated 23-24% of those dying in 1977-1978. Moose were largely absent in winter from the Birch Mountains and the Jackpine Area north of the Firebag River. Seasonal shifts between winter and summer home ranges were made by 34 (76%) of 45 moose; 13 (38%) of these movements exceeded 20 km. No differences (P < 0.05) in homerange size were found among sexes or seasons. Three distinct periods of increased movement among bulls were observed: April-May, Sept.-Oct. and Dec.-Jan. Cow movements were more leisurely and less well defined. Spring (May-June) calf-cow ratios among radio-collared cows >EQ 3 yr old averaged 88:100. Visual observations of radio-collared moose suggested that: moose were least gregarious from April to Aug., cow-bull associations increased in Sept. and lasted through Nov., in Nov. young bulls (1.5-2.5 yr old) were associated with cows more than were older bulls, bull association with other bulls increased in Nov., and cows with calves associated with other adult moose less than did single cows. Uplands were used more than lowlands from June - Sept., and upland use increased in Oct. Lowland use rose in Nov. and Dec., more so by bulls than cows, but decreased from Jan.-March as snow depth increased. Snow depths were greatest witnin lowland cover types. Lowland use on winter home ranges (Dec-March) was related (r2 = 0.60) to availability. Decreased snowfall in winter 1976-1977 resulted in increased lowland use in Feb. and March. Lowland use rose markedly and peaked in April and May. If there are critical habitats for moose, they are likely the open lowlands that apparently provide the 1st high-quality food in spring. The rate of exploitation of moose in this region likely cannot be raised without producing a major population decline. The most promising means of increasing the allowable harvest would be to reduce the high early mortality of calves.

This publication has 3 references indexed in Scilit: