Sentence:  In the southeastern United States, Krohn et al. (1994) hypothesize that the inverse relationship between captures of <WSD>fishers</WSD> and martens by commercial trappers may result from an interaction between competitive displacement of marten by <WSD>fisher</WSD> and the avoidance of areas with deep and frequent snowfalls by <WSD>fishers</WSD> but not martens. 
Meaning of the word marked with <WSD> tags:  A North American marten, "Martes pennanti", that has thick brown fur.