Alton S. Harestad

Scale-dependent habitat selectivity by fishers in South-Central British Columbia

We examined habitat selectivity by fishers (Martes pennanti) at 3 spatial scales in south-central British Columbia, Canada, from 1990 to 1993. We monitored radiomarked fishers and compared their use of habitats with the availability of these habitats at stand, patch, and element spatial scales. Fishers exhibited habitat selectivity for a variety of resources at different spatial scales. They selected habitats based on overhead cover, foraging, and snow interception at the stand and patch spatial scales. Habitats used by fishers for resting and denning were selected at all 3 spatial scales. When using stands or patches of habitat in which the density of resources may have been low, fishers appeared to compensate by selecting, at smaller scales, areas of higher-quality habitat. Because fishers select resources across several spatial scales, knowledge of which habitat requirements can be fulfilled at each scale allows for more effective and flexible management of fisher habitats.

Cover and efficacy of predator-based repellents for Townsend's voleMicrotus townsendii

Predator-based repellents have been used experimentally to control wildlife damage in both agriculture and forestry, but they have not always been effective. We examined the relative importance of cover and predator odors in forage patch selection by Townsends vole,Microtus townsendii, and its behavior related to cover and predator cues. Experiments were conducted in which forage patch and area choices were related to available habitat alternatives. Outdoor enclosures were divided into halves: one side was treated and the other used as a control. Treatments consisting of “cover,” “repellent,” and “cover plus repellent” were compared to controls (no cover, no repellent). In the absence of cover, voles preferred to feed on the side without repellents. When cover was present, voles preferred to feed on the side with cover, regardless of whether or not repellents were present. Voles visited more feeding stations on the side without cover when repellents and cover were present than they visited during cover-only treatments. These additional feeding stations, visited outside of cover, were used only lightly as food sources. The amounts of oats eaten by voles decreased with increasing distance from cover. This inverse relationship had a steeper slope in coveronly treatments compared to cover plus repellent treatments. A selection model based on forage patch selection and a habitat preference hierarchy is proposed. We conclude that predator odors are effective as repellents, but their efficacy depends on habitat conditions. Managers intending to use predator-based repellents must ensure that alternative sites available to pests are better quality habitat than in areas to be protected.

Persistence of Black-Tailed Deer Fecal Pellets in Coastal Habitats

The persistence of fecal pellets from Columbian black-tailed deer (Odocoileus hemionus columbianus) was determined for 2 levels of 3 environmental factors: moisture, substrate, and canopy. Pellet persistence was least in moist, vegetated forest and greatest in dry, bare cutover. After 1 year, the mean number of pellets remaining in pellet groups on moist sites was between 16 and 48% of the original complement of 50 pellets. On dry sites between 50 and 70% of the pellets were present after 1 year. Similar trends occurred for visibility of pellet groups. After 2 years, 5-25% of the pellet groups were visible at moist, cutover sites, whereas 25-75% of the pellet groups were visible at dry, cutover sites. Rates of change of pellet group visibility indicate that the number of pellet groups counted on uncleared plots represent from 1 to 3 x the number of pellet groups that were deposited the previous year. J. WILDL. MANAGE. 51(1):33-37 Pellet group surveys are an established method for studying ungulate density in North America. There are, however, disagreements about the utility of pellet group counts (Collins and Urness 1981, Leopold et al. 1984). The assumptions made to interpret pellet group data are reviewed by Robinette et al. (1958) and Neff (1968) who evaluated pellet count techniques and offered improvements to statistical design. Assumptions made to interpret pellet counts (Neff 1968) are violated for some conditions, thereby invalidating results. Persistence and visibility of pellet groups are factors affecting counts (Wallmo et al. 1962, Fisch 1979) but are rarely attributed much importance. That pellet groups persist for the duration of the deposition period is commonly assumed. Persistence after the deposition period has been addressed by clearing plots or marking existing pellet groups. Methods developed to minimize the influence of differing persistence or visibility, such as clearing plots, are time consuming and sometimes impractical. Although problems are associated with pellet group counts, their simplicity makes them a desirable technique and ensures their continued use by wildlife managers. Our objectives were to measure pellet persistence and visibility in different habitats. Three factors are important in determining pellet group persistence: moisture, substrate, and canopy cover. Evaluation of the direction and magnitude of effects impos d by these factors on pellet group persistence and visibility should allow more reliable interpretation of past results, extension of present findings, and improved sampling design. The B.C. Fish and Wildl. Branch, Can. For. Products Co. Ltd., Univ. British Columbia, and This content downloaded from 157.55.39.177 on Sat, 19 Nov 2016 04:38:53 UTC All use subject to http://about.jstor.org/terms 34 PELLET PERSISTENCE * Harestad and Bunnell J. Wildl. Manage. 51(1):1987 Natl. Sci. and Eng. Res. Counc. provided support through grants to F. L. Bunnell. Simon Fraser Univ. provided computer support.

Fecal genotyping and contaminant analyses reveal variation in individual river otter exposure to localized persistent contaminants

The present study investigated polyhalogenated aromatic hydrocarbon (PHAH) concentrations in feces of known river otters (Lontra canadensis) along the coast of southern Vancouver Island, British Columbia, Canada. Specifically, we combined microsatellite genotyping of DNA from feces for individual identification with fecal contaminant analyses to evaluate exposure of 23 wild otters to organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenylethers (PBDEs). Overall, feces collected from otters in urban/industrial Victoria Harbor had the greatest concentrations of nearly all compounds assessed. Fecal concentrations of OCPs and PBDEs were generally low throughout the region, whereas PCBs dominated in all locations. Re-sampling of known otters over space and time revealed that PCB exposure varied with movement and landscape use. Otters with the highest fecal PCB concentrations were those inhabiting the inner reaches of Victoria Harbor and adjacent Esquimalt Harbor, and those venturing into the harbor systems. Over 50% of samples collected from eight known otters in Victoria Harbor had total-PCB concentrations above the maximum allowable concentration as established for Eurasian otter (Lutra lutra) feces, with a geometric mean value (10.6 mg/kg lipid wt) that exceeded the reproductive toxicity threshold (9 mg/kg lipid wt). Those results are consistent with our findings from 1998 and 2004, and indicate that the harbors of southern Vancouver Island, particularly Victoria Harbor, are a chronic source of PCB exposure for otters. The present study further demonstrates the suitability of using otter feces as a noninvasive/destructive biomonitoring tool in contaminant studies, particularly when sampling of the same individuals at the local population-level is desired.

WINTER DIET OF FISHERS IN BRITISH COLUMBIA

Abstract We identified the stomach contents of fishers (Martes pennanti) collected during winter between 1989 and 1993 from throughout British Columbia. Eighteen types of mammalian and avian prey were found in 256 stomachs. The most commonly occurring species of prey were snowshoe hares (Lepus americanus), red squirrels (Tamiasciurus hudsonicus), and southern red-backed voles (Clethrionomys gapperi). The diets of fishers varied between sexes; female fishers consumed small prey more frequently than did males. This difference in diets is likely related to the extreme sexual dimorphism of fishers and perhaps differences in habitats where males and females forage. The composition and breadth of the winter diets have implications for understanding habitat relationships of fishers.

Effect of Ambient Temperature on the Selection of Rest Structures by Fishers

We examined the effect of ambient temperature on the selection of rest structures by 20 radio-tagged fishers in two areas of central British Columbia during 1991–1993 and 1996–2000. Fishers rested in tree cavities, on rust brooms or tree branches, under pieces of large coarse woody debris (CWD), and in burrows or rock crevices. We located fishers at 86 rest structures and recorded the local ambient temperature at nearby climate stations while these structures were occupied. The type of rest structure selected by fishers varied with local ambient temperature (P=0.005). Temperatures were colder when fishers used CWD structures than when they used branch or cavity structures (P<0.05). Large pieces of CWD may be important habitat elements for fishers during long periods of extremely low temperatures because they likely provide a more favorable thermal microenvironment than that found at other types of rest structures. Our results have implications for habitat management and conservation of old-forest structures for fishers in regions with cold climates.

Summer Feeding Habits of River Otters Inhabiting a Contaminated Coastal Marine Environment

Abstract In two recent studies, North American river otters (Lontra canadensis) inhabiting the urbanized/industrialized harbors of southern Vancouver Island, British Columbia, Canada were found to be exposed to elevated levels of environmental contaminants, primarily industry-produced polychlorinated biphenyls (PCBs). Contaminant exposure in those studies was assessed non-invasively, by measuring chemical residue concentrations in river otter feces collected from established marking sites (latrines). As river otter exposure to contaminants is primarily through their diet, our aim was to characterize river otter prey selection from feces collected at latrine sites inside the contaminated harbors and along the relatively uncontaminated coastline outside the harbor systems. Fish occurred in 95.5% of all feces analyzed, with species of gunnels (Pholidae), sculpins (Cottidae), pricklebacks (Stichaeidae), toadfish (Batrachoididae), clingfish (Gobiesocidae), flatfish (Pleuronectiformes), and snailfish (Liparidae) being the most common prey consumed. Crustaceans were the only non-fish prey identified. Feces collected outside the harbors had a higher prevalence of pricklebacks, clingfish, and greenlings, whereas feces collected inside the harbor systems had a higher prevalence of toadfish and crustaceans. Because of the diversity of the river otters diet, prey species from each of the main families described here should be analyzed for environmental contaminants to fully characterize concentrations of persistent compounds in the food-web. Prey sampling should be location-specific (i.e., inside and outside the urban/industrial harbors) to elucidate possible location effects on contaminant exposure.

DIETS OF BATS IN COASTAL RAINFORESTS ON VANCOUVER ISLAND, BRITISH COLUMBIA

Abstract We caught Myotis lucifugus, M. yumanensis, M. volans, M. evotis/keenii, M. californicus, and Lasionycteris noctivagans in mist nets at Mt. Cain in coastal British Columbia during 1996–1998. We analyzed their feces and determined the percent frequency of occurrence of different prey groups. Bats consumed prey from 9 prey groups. Diets varied significantly between M. californicus and M. lucifugus, but there was substantial overlap of the principal prey groups consumed by all species of bats. These principal prey groups were Diptera, Lepidoptera, Neuroptera, and Hymenoptera. Diets were similar between elevations and among seasons for both M. californicus and M. lucifugus.