and Sndhetta) exposed to industrial activities or transportation corridors are reviewed. Eehaviour patterns of caribou encountering transportation corridors are explainable in terms of adaptive responses to natural environmental features. There is no evidence that disturbance activities or habitat alteration have affected productivity. Transportation corridors have adversely affected caribou numbers by facilitating access by hunters. There are no examples where physical features of corridors or associated disturbances have affected numbers or productivity. Caribou apparently have a high degree of resilience to human disturbance, and seasonal movement patterns and extent of range occupancy appear to be a function of population size rather than of extrinsic disturbance. The carrying capacity of the habitat is based on the space caribou need to interact successfully with their natural predators. Caribou must not be prevented from crossing transportation corridors by the construction of physical barriers, by firing lines created by hunting activity along a corridor, or by intense harassmenta loss in usable space will ultimately result in reduced abundance.

Distribution of the Central Arctic caribou herd is characterized by segregation of the sexes and different habitat preferences by male and female caribou over most of the annual cycle. During all periods except late winter and postcalving, females showed a more northern distribution than did males. Females used riparian habitats less than availability and were generally farther from major river valleys than expected during all seasons except late winter. In contrast, males preferred riparian habitats from late winter to calving and were generally found closer to river valleys than were females from late winter to August dispersal. During the spring and calving periods near the coast females preferred sedge meadow and used riparian habitat less than availability whereas males preferred riparian and tussock tundra and used sedge meadow less than availability. It is theorized that sexual segregation and differential habitat use reflect predator avoidance strategies of females with calves and optimal foraging by adult males.

There was an unusual increase in numbers of caribou (Rangifer tarandus granti) in the Central Arctic region of Alaska from 1981 to 1985. In fall and winter numbers were up to five times greater than at the onset of calving in June. Numbers appeared to double during the month of June each year, then remain relatively stable over the summer period with a further increase in the fall. Ingress of caribou from outside the region in fall was observed in all years and egress in the early spring is postulated. We conclude that a small resident herd inhabits the region year round with numbers increasing through ingress of caribou from the Western Arctic herd possibly beginning as early as June. Increases or decreases in the size of adjacent herds probably will affect the numbers of caribou occupying the Central Arctic region

The mid-winter distribution and densities of the Bluenose caribou herd were compared with previous surveys over six years and were similar in all years except 1981 when exceptionally mild weather prevailed. Differences in group size, distribution and habitat use between sexes were noted in 1983. Caribou were distributed disproportionately to availability of vegetation types and used lakes significantly more than expected based on their occurrence. Male groups used conifer cover more than did female-calf groups which used open areas (lakes, fens, bogs) more than males. Cow-calf groups chose areas with a higher small lake density compared to lake density generally available. Generally caribou preferred habitat between 200 and 300 m in elevation with high densities of lakes less than 1 km2 in size. Snow depths and hardness were greater in most unoccupied habitats than in occupied habitats. Wolves were associated with high densities of cow/calf groups

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