This 1951 paper is based on a study of both fisher and marten started in 1948 in Ontario, although it does not cover all the aspects of that study.

“The amount of cover is certainly an important factor governing the level of survival of both species, and in that respect the later successional stages are most suitable. These stages also provide more denning holes in trees. Limiting factors undoubtedly differ in various regions.” p.500

“...It is shown that proper protection of these mustelids will result in an overflow from game preserves. It appears at present that a well-regulated trapping season, based on adequate information on the allowable harvest, may suffice to warrant the survival and possible even an increase of both species.” p.501

Figures 1 and 2 respectively depict the distribution of fisher and marten in Ontario in 1951 (pp.501,502).

Summary: “The fisher and the marten are either absent, or practically so, from extensive recently logged and burned-over areas. The amount of cover in an important factor governing the level of survival of both species. The fisher appears to survive better in the early successional stages of the forest than the marten.” p.505

Discussion: Marten are very likely to increase and overflow from refuges if given enough time and protection. p.506