The George River caribou herd in northern QuebeclLabrador increased from about 5000 animals in 1954 to 472 200 (or 1.1 caribou.km.') prior to the 1984 calving season. The range used by the herd expanded from 160 O00 to 442 O00 km2 for the period 1971-84. The exponential rate of increase (r) was estimated at O. 11 in the 1970s. Calkfemale ratio in autumn was relatively constant (x = 0.52) from 1973 to 1983, but decreased to about 0.39 in 1984-86. The harvest rate was relatively low in the 1970s (about 3%.yr"), but seemingly increased in the mid-1980s to 5-7% as a result of more liberal regulations and a greater impetus to exploit caribou for subsistence. The cumulative impact of lower calf recruitment and more intensive hunting may have appreciably depressed the growth rate of the herd in 1984-86. A greater year-round competition for food resources and a greater energy expenditure associated with range expansion are presented as probable regulatory factors for the George River herd. It is argued that the nature of caribou-habitat interactions in continental regions generate long-term fluctuations in caribou numbers if human exploitation remains low. At present, wolf predation does not appear to be an important mortality factor capable of regulating the George River herd.

Between 1984 and 1988, the size of the two caribou herds in northern Québec was derived by combining estimates of female numbers on calving grounds in June and composition counts during rut in autumn. Sampling with aerial photos was conducted on calving grounds to determine the number of animals per km2, telemetry served to estimate the proportion of females in the census area at the time of photography in addition to summer survival rate, and helicopter or ground observations were used for composition counts. Observers were able to detect on black and white negatives over 95 percent of caribou counted from a helicopter flying at low altitude over the same area; photo scale varied between = 1:3 600 and 1:6 000. Sampling units covering less than 15-20 ha were the best for sampling caribou distribution on calving grounds, where density generally averaged » 10 individuals-km"2. Around 90 percent of caribou on calving grounds were females; others were mostly yearling males. During the 1-2 day photographic census, 64 to 77 percent of the females were present on the calving areas. Summer survival exceeded 95 percent in three summers. In autumn, females composed between 45 and 54 percent of each herd. The Rivière George herd was estimated at 682 000 individuals (± 36%; alpha = 0.10) in 1988. This estimate was imprecise due to insufficiens sample size for measuring animal density on the calving ground and for determining proportion of females on the calving ground at the time of the photo census. To improve precision and reduce cost, it is proposed to estimate herd size of tundra caribou in one step, using only aerial photos in early June without telemetry

Between 1973 and 1978, 42 muskoxen (Ovibos moschatus), mostly immature, were released northwest of Kuujjuaq, along the south shore of Ungava Bay. Helicopter censuses, complemented by ground observations, were conducted over 725 km2 in 1983 and 1986: 148 and 290 animals were counted during the first and second surveys, respectively. The finite rate of increase of the population averaged 1.25 during the 3-year interval; that rate indicates high fecundity and low mortality, because the maximum finite rate of increase is 1.30 if all animals survive and if females first calve at 3 years of age and thereafter produce one calf each year. Ground observations confirmed a high productivity: calves constituted 26 and 23% of the population in 1983 and 1986, respectively; in terms of calves per 100 mature cows, the respective ratios were 97 and 86. Some animals dispersed up to 650 km from the area of release; populations may be establishing themselves in new locations. Muskoxen are now well established in the tundra of northern Quebec.