Territoriality and Home-Range Fidelity of American Martens in Relation to Timber Harvesting and Trapping

Abstract

Timber harvesting and trapping may decrease population density or disrupt sex ratios of American martens (Martes americana), potentially affecting fitness by altering spatial relations such as site fidelity and territoriality. We compared homerange fidelity and overlap within and between sexes for 143 (77 M, 66 F) resident, nonjuvenile martens during 1991–1998 among 3 contiguous study sites: (1) an untrapped, unlogged forest reserve (FR) with high marten density (0.63 marten/ km²); (2) an untrapped, extensively clearcut industrial forest (UIF) with moderate marten density (0.31 marten/km²); and (3) a trapped, extensively clearcut industrial forest (TIF) with low marten density (0.19 marten/km²) Mean fidelity was 67% for consecutive seasons and 55% for consecutive years, and did not differ among sites (P≥0.33) or between males and females (P>0.21). Extent of samesex home-range overlap was greater in FR than in either logged site for males (P<0.01), but did not differ between UIF and TIF for males (P=0.16) or females (P=0.10). For females, incidence of overlap with male ranges did not differ among sites (P=0.07), although there was a trend of lower incidence in the logged sites, particularly TIF. Incidence of opposite-sex overlap for males was lower in TIF than UIF (P<0.01). In the logged sites, martens established home ranges within residual forest patches that overlapped with ranges of potential mates, were apparently defended against consexuals, and were maintained through consecutive seasons and years similarly to the unlogged reserve. These strategies maintained population social structure and ensured breeding opportunities among females in the trapped and untrapped, logged areas. Higher fur-trapping pressure, greater habitat fragmentation, or isolation of a trapped population from a source population might reduce opposite-sex overlap among females and create social instability.