The discovery of unusually high populations of the heather vole, Phenacomys ungava, afforded an opportunity to study the life history of this uncommon microtine. Detailed notes are recorded for the animal's development, breeding behavior, nesting habits, habitat requirements, food preferences, enemies and behavior. Where possible, the observations have been compared to those on the closely related Phenacomys intermedins, with the intention of throwing light on the problem of whether the two species are conspecific. Using these non-morphological criteria, the two species do seem to be very similar.
It is pointed out that the rarity of this species in trap-line catches may be due to unsuitable trapping methods rather than to the actual scarcity of the vole.