Dynamics of Moose populations near Rochester, Alberta, 1975-1978

Abstract

A Moose population was studied near Rochester, Alberta, from October 1975 to April 1978. Mean densities of Moose on 228 km? of nonagricultural land were 0.64/ km? in winter 1975-1976. Fifty-nine Moose were radio-collared, and an additional 66 were color-collared. Sixty-one percent of the captured Moose (excluding calves) were yearlings and 2-yr-olds. The combined yearling-and-adult sex ratio averaged 25 bulls to 75 cows during winter 1975-1977. Radio-collared Moose exhibited both "migratory" and "nonmigratory" movement patterns. Distances between seasonal range centers of migratory individuals were significantly greater for bulls, i.e., 13 vs. 7 km. There appeared to be no difference between seasonal home range sizes of bulls and cows. Long-distance "dispersal" movements occurred among 1.5-to 2.5-yr-olds. Mean annual survival of radio-collared yearlings and adults was estimated at 0.84. Calf survival estimated from disappearance rates of calves of radio-collared cows, from demographic data, and from survival of radio-collared calves averaged 0.67 annually. Fecundity of migratory cows was probably higher than of nonmigratory ones. Calves averaged 39% of the winter population in six aerial surveys. Moose were located on aspen islands within muskegs during summer months and in open and treed muskeg during September-November. Movements to tall high-density upland aspen and conifer stands occurred in December and continued into March. During the last week of March and first week of April there was a marked shift into lowland areas. February and March were the only months when Moose were not located further from human disturbances than would be expected ina random distribution. The percentage of Moose having about one-third or more cleared land within a I-km radius of their observed location increased from 17% in November to 48% in March. In October 1975, as part of the Alberta Oil Sands determined from radio-tracking. Environmental Research Program (AOSERP), we intensified our studies of Moose (Alces alces) near Study Area Rochester, Alberta. During the previous 10 winters The 287-km2 (112-mi2) Rochester Study Area was we had routinely counted, classified (by sex and age), located 100 km north of Edmonton (Figure 1). About and plotted locations of Moose on 179 km? while 21% was cleared for agriculture; 43% was upland conducting aerial surveys of Coyotes (Canis latrans) forest dominated by Trembling Aspen (Populus tre-and White-tailed Deer (Odocoileus virginianus). muloides) and Balsam Poplar (P. balsamifera) with These surveys indicated that the Moose population intermixed stands of Jack Pine (Pinus banksiana) and was increasing rapidly, and that both reproductive White Spruce (Picea glauca); 32% was bog containing and recruitment rates were high (Rolley and Keith scattered Tamarack (Larix Jaricina) and dense stands 1980). of Black Spruce (Picea mariana); and 3% consisted of Because the Moose population at Rochester was _ ponds, lakes, and rivers. The western and southern unhunted, essentially without predation, and onwhat sections of the study area bordered economically-appeared to be excellent range, it provided a fine marginal farmland. Climate, soils, topography, and opportunity to measure rates of increase and other vegetation of the area have been summarized else-demographic data under what were optimal condi-where (Weatherill and Keith 1969; Rusch et al. 1971; tions for Moose in northcentral Alberta. In other Keith and Windberg 1978). words, the Rochester population could be used as a There were three "survey" areas within the Roches-base against which to compare the dynamics and ter Study Area (Figure 1). The initial survey area of growth potential of other regional populations. The 179 km?(hereafter called the Helicopter Survey Area) Rochester population also offered opportunities to was established in 1965 for monitoring Coyote and examine relationships between human disturbances White-tailed Deer populations, but Moose were also and seasonal distribution and habitat usage by counted each winter. The second area of 228 km? (the Moose. Moose Survey Area) was selected because Moose The present paper is based on analysis of data numbers appeared high there, and it was bounded by obtained between October 1975 and April 1978. It is | easily recognized road systems. The third area of 143 primarily concerned with population demography, km? (the Intensive Survey Area) was mainly forested movements, distribution, and habitat utilization as and had the highest Moose densities. a9