Odocoileus hemionus columbianus

Odocoileus hemionus columbianus (‘Columbian Black Tail Deer’) is the most common deer species west of the Cascades in Oregon. The size can vary depending on the habitat. A large, mature male can grow up to 90 cm tall at the shoulder and weigh up to 90 kg (200 lbs) while smaller males are up to 75 cm tall and 45 kg (100 lbs). Mature females grow to a stature and weight slightly less than that of the males.

The colors of the fur are seasonal. In winter, the fur is brown tinged with red or gray and hints of black. The tail is black with a white base, but not an extensive white rump patch as in the ‘white tail deer’. The belly and throat is whitish. In the summer, the body colors change to buff with reddish tinges and no black highlights. Fawns are a shade of brown with white spots, but the tails are characteristic of the adults.

The antlers of the buck are characteristic of the species, forking twice resulting in nearly equal points in addition to the nearly basal point, referred to as the ‘eye guard’, on each antler. At the beginning of spring, the buck will shed his antlers, with the replacements coming immediately. In late summer, the velvet covering the new antlers is removed by rubbing against trees and bushes.

O. hemionus columbianus will browse many things, including conifers. In the winter, herds remain deep in coniferous woods for warmth and availability of food. The mountain herds will move to lowlands to take advantage of the warmer temperatures and abundant foods, in comparison.

Adults mate in the fall and the fawns are born in the spring. The number of young born per litter ranges from a single fawn up to three, depending on the age and nutritional state of the mother. O. hemionus columbianus can live more than 10 years, 20 year old deer have been reported. The average age is much less than 10 years, however.

The picture above was taken at Baskett Slough National Wildlife Refuge in McMinnville, Oregon in early spring of 2008.

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References

Cogger, H.G., E. Gould, J. Forshaw, G. McKay and R.G. Zweifel (1993) The Encyclopedia of Animals. Fog City Press, San Francisco, CA

E.N. Kozloff (1976) Plants and Animals of the Pacific Northwest. University of Washington Press, Seattle and London.