Temporal dynamics in the movements habitat use activity and spacing of reintroduced fishers in northwestern Montana

Abstract

In the final 2 years of a 4 year project to reintroduce fishers (Martes pennanti) to the Cabinet Mountains of Montana, I translocated 78 fishers (1.0:1.3M:F; 33 were juveniles) from Wisconsin in 1990Wisconsin in -1991.Radiotags were placed on 25 animals in October 1990 to allow monitoring of movements, activity, habitat use, and fates through August 1991.Six animals were implanted with intraperitoneal transmitters, and 19 animals were radio collared.Half the radiotagged animals were soft-released, with the remaining hard-released.Ground triangulation, aerial locations, and 24-hour remote monitoring revealed activity, movements, habitat use, and homerange establishment.Seasonal and permanent homerange and core activity areas (90% and 50% utihzation volumes, respectively) were calculated with adaptive kernel analysis.Habitat selection, based on planimetric and hydrographic variables, was estimated using a nonmapping technique on a Geographic Information System.During the 2-week post-releases period, soft-and hard-released fishers did not differ in movement rates (p = 0.10), activity levels (p=0.89), or mortality rates.Twenty-four fishers remained in the general release area, while 6 dispersed 9.4 -18.0 km.Of the total mortalities (n=14), seven were from predation within the first 2 months of release.Most animals stabilized through winter; 9 females and 5 males maintained winter homeranges.Habitat selection during the winter was minimal: high activity levels, low movement rates, and a shift to nocturnal activity may indicate that harsh environmental conditions limited movements of the fishers.During the breeding season, fishers increased movement rates, and used low elevation habitats close to water, with flat or shallow slopes.Adult males increased movement rates, and the single adult male homerange increased from 3.6 to 99.3 km^.Some females shifted core activity areas, resulting in overlap with the adult male and with each other.Juvenile males did not appear to respond to breeding season.After breeding season, females again shifted core areas to re-establish intrasexually exclusive areas.Nine animals (2 males and 7 females, including 2 from a prior release) estabhshed permanent homeranges.The fishers settled in low elevation, mesic habitats, in proximity to 2 prior residents; these prior residents may have served as indicators of habitat quality.Montana females maintained small homeranges compared to standardized estim ates for Idaho animals, possibly due to varying habitat quality or intrasexual competition; alternatively, this may be related to the colonization process.Although mortality removed 14 of the 25 animals from the population, higher settlement rates were seen in this study as compared to the first 2 years of translocations (Roy 1991).This is discussed in fight of settlem ent and colonization processes, and implications for future rintroductions.The rintroduction process is examined at several scales, from anim al husbandry to metapopulation dynamics.