While often described as pale with few to no markings, which would be typical of an insular ungulate,[3] this description is likely based on aged museum skins, as the remains of recently killed individuals photographed in 1908 appear darker in colour.

[9] The introduction of black-tailed deer to Graham Island took place on multiple occasions between 1878 and 1925,[10] and could have potentially played a role in the caribou's demise through competition for resources and the spread of disease.

Clearcutting was occurring on the island around this time as well, and along with providing further feeding opportunities for the introduced black-tailed deer, which in turn helped bolster their numbers,[10] it is possible the destruction of woodland negatively affected the caribou directly via habitat loss.

Dawson's caribou were hunted by both indigenous people and European settlers for their pelts, as part of the fur trade,[4] which presented another threat to the population.

The last definite sighting of a live Dawson's caribou occurred on November 1, 1908, when a small group was observed, this included a pair of adult bulls, one cow and a calf.