. The Canadian field-naturalist. Natural history. 1970 Notes 389 lively conspicuous to a predator and less ready than others to take flight (Leuthold 1966). Inter- specific associations may encourage predators to be selective and concentrate their attentions on animals of one species because they are slower or less wary than animals of other species, or because they are calving while others are not. Inter-specific associations of ungulates are con- spicuously rare in temperate biomes. Noteworthy comments appear from time to time describing associations between isolated deer and cattle (for ins
. The Canadian field-naturalist. Natural history. 1970 Notes 389 lively conspicuous to a predator and less ready than others to take flight (Leuthold 1966). Inter- specific associations may encourage predators to be selective and concentrate their attentions on animals of one species because they are slower or less wary than animals of other species, or because they are calving while others are not. Inter-specific associations of ungulates are con- spicuously rare in temperate biomes. Noteworthy comments appear from time to time describing associations between isolated deer and cattle (for instance: Dansie 1969), and associations between different species of deer are, apparently, even more rare. Although three or four species of deer may inhabit the same forest (Cadman 1967) and obviously share some common environmental requirements, their inter-relationships rarely in- clude direct social interaction. In comparison to tropical and temperate biomes, the high latitudes support few species of ungulates and each is widely divergent from the others in its morphology, behaviour and environ- mental requirements. Despite some overlap in habitat, the three ungulate species of interior and northern Alaska (moose, Alces alces. caribou, Rangifer tamndus, and Dall sheep Ovis dalli) are ecologically divergent and rarely experience physi- cal proximity. In some regions only one of these species finds suitable environment; such as the extensive Tanana Valley lowlands where a dense population of moose is present. In the Alaska Range to the south of this region, moose generally prefer the lower elevations where riparian willows (Salix sp.) occur; Dall sheep exploit the steep sided canyons, high basins and inter-connected ridges; and caribou largely occupy intermediate environment including foothills, plateaux and middle elevations on the sides of broad valleys. However, caribou are less predictable than moose or Dall sheep. Their highly nomadic behaviour takes them through all types
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