Shannon M. Crowley

Spatial Ecology of a Canada Lynx Population in Northern Maine

Abstract Canada lynx (Lynx canadensis) were listed as a federally threatened species in 14 states at the southern extent of their geographic range in March 2000, with Maine being the only state in the northeastern United States known to support a resident population. Relatively little information is known about the ecology of lynx living at the southern edge of their range, including range requirements, movements, and spatial organization. Basic knowledge of lynx ecology is needed for federal recovery planning efforts. Between 1999 and 2004, we trapped and radiocollared 43 lynx (21 M, 22 F) in northern Maine in an intensively managed and predominantly early successional forested landscape. We estimated diurnal annual and seasonal home-range size for male and female lynx using the 85% fixed-kernel home-range estimator. Annual home ranges of adult male lynx (x̄ = 53.6 km2) were more than twice the size of adult female home ranges (x̄ = 25.7 km2). Home ranges of adult females during snow periods (x̄ = 38.3 km2) were nearly 3 times larger than their snow-free-period ranges (x̄ = 14.3 km2), whereas, snow-free ranges of adult males (x̄ = 58.8 km2) were slightly larger than their snow-period ranges (x̄ = 45.2 km2). We observed a limited amount of home-range overlap among lynx of the same sex (F: x̄ = 17.2%; M: x̄ = 11.8%). Lynx of opposite sex showed more extensive overlap (x̄ = 24.3%). Most home-range shifts of resident lynx were typically not extensive. Based on territory mapping, we estimated a minimum lynx density of 9.2–13.0 lynx/100 km2. We observed lynx spatial ecology and densities that were more similar to northern lynx populations when hares were abundant than to other southern lynx populations, suggesting that region-specific studies under varying habitat conditions and hare densities are needed to ensure realistic recovery goals and effective management of lynx at the southern extent of their range.

Diurnal Habitat Relationships of Canada Lynx in an Intensively Managed Private Forest Landscape in Northern Maine

Abstract In March 2000, Canada lynx (Lynx canadensis) were listed as a federally threatened species in 14 states at the southern periphery of their range, where lynx habitat is disjunct and snowshoe hare (Lepus americanus) densities are low. Forest conditions vary across lynx range; thus, region-specific data on the habitat requirements of lynx are needed. We studied lynx in northern Maine, USA, from 1999 to 2004 to assess quality and potential for forests in Maine to sustain lynx populations. We trapped and radiocollared 43 lynx (21 M, 22 F) during this period and evaluated diurnal habitat selection by 16 resident adult lynx (9 M, 7 F) monitored in 2002. We evaluated lynx selection of 8 habitats at multiple spatial scales, and related lynx habitat selection to snowshoe hare abundance. Lynx preferred conifer-dominated sapling stands, which supported the highest hare densities on our study site (x̄ = 2.4 hares/ha), over all other habitats. The habitats where lynx placed their home ranges did not differ by sex. However, within their home ranges, males not only preferred conifer-dominated sapling stands, but also preferred mature conifer, whereas females singularly preferred conifer-dominated sapling stands. Approximately one-third of Maines spruce–fir forest and nearly 50% of our study area was regenerating conifer or mixed-sapling forest, resulting from a disease event and intensive forest management (e.g., large clear-cuts). Our findings suggest that current habitat conditions in Maine are better than western montane regions and approach conditions in boreal forests during periods of hare abundance. We recommend that forest landowners maintain a mosaic of different-aged conifer stands to ensure a component of regenerating conifer-dominated forest on the landscape.

Spatial and behavioral scales of habitat selection and activity by river otters at latrine sites

Abstract Animals interact with their environment at multiple spatial, temporal, and behavioral scales. Few studies of selection for latrine sites by river otters (Lontra canadensis) have considered spatial scale, and no studies have integrated scales of behavior. We used an information theoretic model comparison approach to identify elements of otter habitat that influence the presence, consistency, and intensity of latrine-site activity at 2 spatial scales. We identified and monitored 73 latrine sites in central British Columbia, Canada, during the open-water season in 2007 and 2008. We inventoried latrines and randomly selected sites along the adjacent shoreline, and used those data in the form of a binary resource selection function to model fine-scale selection of latrine sites. At the scale of the landscape, we used a resource selection function and data from geographic information systems to model coarse-scale selection of latrine sites. Drawing on those same data, we used binary and count models to quantify factors that contributed to the consistency (high versus low use) and intensity (number of scats) of otter activity at latrine sites. Fine-scale habitat characteristics were better at predicting the presence of latrine sites when compared to coarse-scale geographic information system data. In general, the presence, consistency, and intensity of latrine activity at the fine scale were influenced by visual obscurity, larger trees, and characteristics of conifer trees. The presence of latrine sites at the coarse scale could not be accurately described by any of the models. The consistency and intensity of activity of otters at latrine sites at the coarse scale, however, was best predicted by habitat characteristics beneficial to fish. These results provide insight into the spatial and behavioral scales of latrine-site activity by river otters that can be incorporated into management, monitoring, and conservation strategies.

Within-Stand Selection of Canada Lynx Natal Dens in Northwest Maine, USA

Abstract Canada lynx (Lynx canadensis) were listed as threatened in the contiguous United States under the Endangered Species Act in March 2000. Little information on lynx ecology at the southern extent of their range was available at the time of listing, and no ecological studies had been conducted in the eastern USA. Between 1999 and 2004, we investigated habitat selection at natal dens in northern Maine to address questions on the importance of forest conditions to denning requirements. We compared within-stand characteristics of 26 den sites to general characteristics of the stands containing dens. We used logistic regression to identify components within stands that distinguished natal dens from the residual stand and used the information-theoretic approach to select models that best explained lynx den-site selection. The top-ranked model had 2 variables: tip-up mounds of blown-down trees and visual obscurity at 5 m from the den (wi = 0.92). Within-stand structure was useful for predicting lynx den-site selection in managed forests in Maine and suitable denning habitat did not appear to be limiting.

Spatio-Temporal Variation in River Otter (Lontra canadensis) Diet and Latrine Site Activity

Abstract: Fluctuations in the distribution and abundance of prey resources are an important influence on the foraging ecology of carnivores. Spatio-temporal variation in the diet of river otters (Lontra canadensis), however, is not well understood. In addition, we have limited knowledge about seasonal changes in otter activity at latrine sites and how these changes may relate to changes in otter diet. We used a combination of scat content and stable-isotope analyses to assess the contributions of different prey items to otter diet. We investigated the spatio-temporal variation in the availability of prey groups as it influenced the composition of otter diet and the number of scat deposited at latrine sites. A combination of fish spawning period, water-body type, and lake best described the presence of salmonidae, minnows, and insects in otter scats. The number of scats was best described by a two-week calendar time measurement and geographic location. Scat deposition was positively influenced by a time period when no fish were spawning (early July) and the kokanee (Oncorhynchus nerka) spawning period (early September). In general, the stable-isotope analysis agreed with the results of the scat content analysis: fish dominated the diet, with lesser contributions from other prey items. The stable-isotope analysis, however, suggested that sockeye salmon, larger species of fish (burbot, lake trout), and birds contributed more than was revealed by scat content analysis. Management strategies require accurate and unbiased information on wildlife distribution and abundance that is often measured from surveys of sign; this study provides some of the critical information needed to interpret surveys for river otters. We also suggest implications for other wildlife species.

The role of demographic and environmental variables on the presence of snow tracks by river otters Lontra canadensis

Unknown causes of heterogeneity in the presence or detection of wildlife tracks and other signs could bias interpretations of population indices derived from surveys. These surveys can be the basis of management decisions for populations of wildlife. However, we know very little about potential biases affecting the presence of tracks in the landscape. We used an Information Theoretic Model Comparison approach to investigate the role of environmental, demographic and behavioural influences on the presence of river otter Lontra canadensis snow tracks in central British Columbia, Canada, from January to March 2008. We repeatedly located five radio-collared otters and recorded the presence of tracks within an estimated 100-m radius of the otters location. We used combinations of five variables to develop logistic regression models that predicted the presence or absence of snow tracks when the location of otters was known. The presence of snow tracks was best described by a model containing covariates for gender and movement distance per day. The probability of detecting snow tracks was higher for male compared to female otters and was positively related to the daily movement distance of the individual animal. Track-sign heterogeneity among individuals could bias surveys that assess and monitor river otter populations, and should be incorporated into the design and interpretation of track surveys.

Timing Moose Pellet Collections to Increase Genotyping Success of Fecal DNA

Abstract Fecal pellets can serve as a noninvasive source of DNA for identifying the distribution of individual animals when conducting population estimates. The quality of fecal DNA, however, can b...