Complex sentence: Species which utilize underground or rock dens tend to be more vulnerable to predatory attacks by brown bears, several mustelids including badgers are not infrequently preyed upon, and seemingly even arboreal martens may be attacked (especially if unhealthy or caught in furbearer traps).
Split into simpler sentences: Species which utilize underground or rock dens tend to be more vulnerable to predatory attacks by brown bears. Several mustelids, including badgers, are not infrequently preyed upon, and seemingly even arboreal martens may be attacked (especially if unhealthy or caught in furbearer traps).