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Landscape connectivity is a key component for successful dispersal of wildlife. Many approaches to quantify landscape connectivity utilize landscape characteristics and wildlife behavior in response to those characteristics, whereas other approaches focus on wildlife dispersal behavior. Combining landscape structure and wildlife behavior (e.g. movement, food acquisition, response to predation risk) provides critical information for conservation and management of many species. Individual-based models (IBM) are useful tools for evaluating the interaction between landscape characteristics and individual behaviors, thereby providing insights into management and conservation. Our objective was to evaluate the effect of reductions in landscape connectivity on northern flying squirrel dispersal movements under alternative timber management scenarios within the modeling framework of a spatially-explicit IBM. We simulated timber harvests of 6% and 9% of old-growth forest, the primary habitat for this species, distributed across 5, 10 or 15 harvest locations. We measured the influence of these scenarios upon landscape connectivity for flying squirrels. Landscapes with greater connectivity exhibited longer flying squirrel dispersal distances, more sinuous dispersal paths, and a greater total area of landscape utilization. However, connectivity was not directly correlated with habitat loss. The harvest scenario with 6% harvest of old growth distributed among 15 harvest locations had the lowest connectivity index value despite other scenarios modeling a greater percentage of old growth loss. The IBM demonstrated the importance of behaviors such as path tortuosity and movement rates in conjunction with landscape configuration in influencing the movement of dispersing individuals. The spatially explicit IBM provided a framework to evaluate connectivity from a fine-scale behavioral rather than structural perspective as well as to evaluate the distribution of new home range locations, which could be a useful management tool when evaluating the influence of landscape heterogeneity and stochastic behavior on wildlife movement and dispersal.

A history of timber harvest in West Virginia has reduced red spruce (Picea rubens) forests to < 10% of their historic range and resulted in considerable habitat fragmentation for wildlife species associated with these forests. The Virginia northern flying squirrel (Glaucomys sabrinus fuscus) has been described as a red spruce obligate subspecies that must traverse this fragmented landscape to disperse among remnant red spruce patches. Food availability in the forest matrix surrounding red spruce may be a limiting factor to successful dispersal of G. s. fuscus. We examined the diet of flying squirrels using stable isotope analysis and used vegetation surveys to determine the availability of diet items in the habitats encountered by G. s. fuscus in the matrix surrounding red spruce fragments. Stable isotope analysis suggested hypogeous fungi, epigeous fungi, and invertebrates contributed the most to the diet of G. s. fuscus, followed by lichen. Tree buds contributed the least in spring, and beechnuts contributed the least in fall. The vegetation surveys revealed that no habitat type had a greater availability of the diet items that contributed most to the assimilated diet of G. s. fuscus, suggesting that stand age and structure may be more important for diet-item availability than habitat type.

Communities include habitat generalists whose resource use overlaps specialists. Habitat selection is a mechanism that allows competing species to coexist. Interspecific competition can facilitate coexistence directly or through promoting differential habitat selection. Habitat selection and interspecific competition can vary with population density; however, their roles in determining relative abundance of species across habitat space are poorly understood. We studied Peromyscus keeni, which flourishes in a range of habitats in southeastern Alaska, and Myodes gapperi, a specialist of mature coniferous forests in western North America, to elucidate how these mechanisms may facilitate coexistence in temperate rainforest. We used stepwise multiple regressions of minimum known alive (standardized to unit variance) across 1 ha grids during spring 1999–2000 and autumn 1998–2000 to determine contributions each variable, in each significant regression model, made to the variance in abundance for each species. We determined relative contributions of interspecific competition versus habitat selection in explaining species' habitat use among four different types of rainforest habitat. Intensity of interspecific competition (both directions) varied with population density and season. Habitat variables, rather than interspecific competition, explained variation in species' abundance at population peaks when intraspecific competition would be intense. Interspecific competition, with habitat, was significant at all other times. Our findings suggest habitat selection and interspecific competition explain variation in the abundance of both species among habitats, but contributions vary seasonally and with density. During spring, interspecific competition seemingly plays a greater role at higher densities, but during autumn interspecific competition increases its relative contribution as population density decreases.

Whereas roads that bisect habitat are known to decrease population size through animal-vehicle collisions or interruption of key life history events, it is not always obvious how to reduce such impacts, especially for flying organisms. We needed a quick, cost-efficient and effective way to determine how best to decrease vehicle-caused mortality while maintaining habitat connectivity for the federally listed Oregon silverspot butterfly, Speyeria zerene hippolyta. Therefore, we gathered targeted ecological information that informed selection of a mitigation option prior to implementation. We sampled butterfly behavior and environmental conditions along a highway and conducted a small-scale experiment along a decommissioned road corridor used by these butterflies. Using our findings, we recommended vegetation management and helped managers eliminate options they were considering that would be ineffective such as increasing shade or wind in the road, and installing fencing or hedgerows aimed at directing flight above traffic. This quick and inexpensive approach of using ecological observations and small-scale experiments to evaluate the likely success of each available mitigation option can be used to determine effective, species-specific solutions for reducing traffic impacts on pollinators and other small, flying organisms of conservation concern.

Swamp rabbits (Sylvilagus aquaticus) inhabit bottomland hardwood forests and rely on key microhabitat features found in this forested wetland system. Research comparing key features of swamp rabbit habitat across the species' geographic range is lacking. In this study, we compared 13 microhabitat characteristics at sites associated with 2 distinct behaviors (form and latrine) of swamp rabbits at the northern extent of their distribution (southwest Indiana, northwest Kentucky) with sites from the species' core distribution (Arkansas). There were significant differences in vegetation structure including canopy cover, basal area, stand density, and stem density between Indiana, Kentucky, and Arkansas sites for both form and latrine locations. At the northern periphery, where swamp rabbit populations are of conservation concern, we found that habitat is composed of fewer key components that are ecologically important to swamp rabbits such as canopy gaps, downed woody material, and cover. Wildlife managers interested in providing swamp rabbit habitat should recognize microhabitat components (i.e., canopy gaps, downed woody material) that are favorable for swamp rabbits and attempt to supply these elements through management actions such as uneven-aged silvicultural practices. © 2015 The Wildlife Society.

The survival of many species may be dependent on their ability to exist in human-altered landscapes within metapopulations; in turn, metapopulation persistence is dictated by the ability of individuals to move effectively among patches to promote recolonization. The Taylor’s checkerspot butterfly (Euphydryas editha taylori) is a species that does not naturally occur in fragmented landscapes, yet it is now restricted to a handful of small isolated prairie habitats. Current recovery plans aim to establish a stable metapopulation; however, to date little is known about the species’ ability to move across the landscape. In 2010 and 2011, we conducted marking, tracking and boundary surveys to explore the movement dynamics of adults within two sites in Oregon, USA. Over the survey period, we marked 136 male butterflies, tracked 174 individuals and observed the behavior of 1,576 individual butterflies at site boundaries. Our study revealed a significant sex-bias in the movement dynamics of the Taylor’s checkerspot in both suitable habitat and surrounding matrix. Males were highly motile, whereas females appeared sedentary, rarely moving from their natal site. The limited dispersal behavior of females indicates that populations cannot persist naturally in a metapopulation and thus are at high risk of extinction. Based on our findings, we recommend that managers take proactive measures to increase or enable dispersal (including translocation) to existing and/or restored sites.

Despite widespread use of fecal pellet-group counts as an index of ungulate density, techniques used to convert pellet-group numbers to ungulate numbers rarely are based on counts of known individuals, seldom evaluated across spatial and temporal scales, and precision is infrequently quantified. Using DNA from fecal pellets to identify individual deer, we evaluated the relationship between pellet-group count and count of Sitka black-tailed deer (Odocoileus hemionus sitkensis) during a 3-year study (2006–2008) in 3 watersheds in southeast Alaska, USA. We surveyed 141,054 m2 of transect, counted 10,569 pellet groups, and identified 737 unique deer. We used a multilevel mixed-effects generalized linear model to analyze expected deer count as a function of pellet-group count. Pellet-group count was a significant predictor of DNA-based index of deer count, but that relationship varied by transect, watershed, and year, indicating that extrapolation of a single linear relationship across space and time was not possible. More importantly, most of the variation in our models was residual and unexplained. Assuming that our DNA-based results were a more accurate and precise metric of true deer count, we do not support the use of pellet-group count to index deer count in southeast Alaska unless confounding factors are accounted for at fine spatial (e.g., habitat patch) scales. Because of the difficulty in routinely evaluating the influence of confounding variables in remote and unmanaged landscapes, we suggest that wildlife programs in these environments consider alternatives, such as DNA-based methods, for monitoring trends in ungulate populations. © 2013 The Wildlife Society.

We evaluated the northern flying squirrel (Glaucomys sabrinus griseifrons), a known associate of key habitat features and processes of old-growth forest, for its capacity as a broad-scale ecological indicator of temperate rainforest ecosystem condition in southeastern Alaska, USA. We utilized a spatially explicit, resource-selection function to evaluate its distribution relative to landscape composition and structure at local (within home-range) and broad (home-range selection) spatial scales, followed by a moving-window analysis to model patch occupancy across this landscape. We found strong support for the influence of type, size, and compositional elements: large, old-growth patches were selected at both spatial scales, and regenerating forest patches ≤40 yrs old were selected against at the broader scale. More importantly, we found that occupancy was related to critical thresholds in composition: patches required ≥73% old-growth forest cover or a minimum total area of 73 ha of old-growth forest to be occupied by flying squirrels. A non-uniform pattern of selection for patches with higher structural connectivity at the local scale, but not at the broader scale, was likely a result of the “empty forest” phenomenon, in which remnant patches were inaccessible in this fragmented landscape. These results are consistent with recent studies of this and related species and suggest that occurrence of northern flying squirrels in southeastern Alaska is influenced by a number of landscape structure and compositional variables that relate critically to late-seral forest conditions. These findings shed new light on the utility of this species as an ecological indicator and its functional relevance to the resilience of fragmented forest ecosystems.

In many regions of the world, forest management has shifted from practices emphasizing timber production to more sustainable harvesting that integrates ecological values, including maintenance of biodiversity, wildlife habitat, and ecological goods and services. To this end, management strategies emphasize retention of stand structures that meet the needs of forest-obligate wildlife species and enhance connectivity across landscapes. However, little is known about the effects on arboreal rodents of varying the amount or spatial distribution of retained structures. We quantified the responses of northern flying squirrels ( Glaucomys sabrinus ) to retention harvests of varying levels (15%, 40%, 75%, and 100% of original basal area) and spatial patterns (trees uniformly dispersed vs. aggregated in 1-ha patches), using six experimental treatments replicated at three locations in southwestern Oregon and Washington. Relative abundance of northern flying squirrels decreased following harvest; minimum number of squirrels known alive (MNKA) in the control (100%) and 75% retention treatment was significantly higher than in the 15% or 40% treatments. In mixed-effects regression models, MNKA increased with treatment-unit basal area and amount of surrounding mature (>80-year-old) forest, suggesting that squirrel abundance was influenced by local structure and landscape-scale variables. However, only basal area contributed to best-fit models of reproductive female abundance. Our results suggest a threshold response of northern flying squirrels to green-tree retention somewhere between 40% and 75% that is likely to be influenced by the spatial pattern of retention and landscape context. This study underscores previous conclusions that northern flying squirrels are sensitive to logging at both local and larger landscape scales, and demonstrates the current minimum retention standard of 15% will not provide suitable habitat for this species.

Indigenous forests across North America have been and continue to be transformed. The implications of these changes are far reaching and include the loss of habitat, biological diversity, and ecological services, as well as diminished air and water quality. The northern flying squirrel is a forest obligate that achieves its highest density in old growth, facilitates critical symbiotic relationships, and is an essential prey of disturbance-sensitive predators. Its reliance on old-forest attributes varies with community diversity, and its sensitivity to isolation renders it an ideal indicator of landscape connectivity. The results of numerous studies reveal the squirrel's acute sensitivity to disturbance at multiple spatial scales, which renders it an effective sentinel of forest ecosystem processes and condition over both geological and ecological time scales. Therefore, a thorough understanding of its ecology can inform projections and the effective mitigation of continued disturbance of ecological commun...

Advances in the application of stable isotopes have allowed the quantitative evaluation of previously cryptic ecological processes. In particular, researchers have utilized the predictable spatial patterning in natural abundance of isotopes to better understand animal dispersal and migration. However, quantifying dispersal via natural abundance alone has proven to be of limited utility for species exhibiting short- or mid-distance dispersal events, including most mammalian species. In previous experimental work, we demonstrated that consumption of 1 dose of isotopically enriched baits elicited a distinct ‘‘mark’’ in hair of captive martens (Martes spp.). Herein, we report findings from a field test of our isotopic enrichment approach to mark freeranging animals and quantify dispersal of martens across forest stands at sites in southeastern Alaska and northern British Columbia. In the field, we supplemented bait used in single-capture hair traps with the amino acid glycine artificially enriched in 2 H, 13 C, or 15 N. By applying unique combinations of artificially enriched isotopic markers within discrete forest stands, the isotopic signature of collected hair reflected the forest patch where the individual originated. From our isotopic marks, we were able to infer dispersal events between forested stands and, thus, estimate rates and approximate dispersal distances. Our findings demonstrate that isotopic enrichment can be a cost-effective method to mark the hair of midsized mammals for the quantification of dispersal.

We monitored 15 radio-collared raccoons (Procyon lotor) on Davies Island in March 1987 - May 1988 to determine the extent to which individual tree attributes or spatial configuration of plant associations (habitat types) across the landscape influenced den use. Of 1091 verified den sites, 428 were in tree cavities. Raccoon occurrence among 4 cover types differed from that expected based on the total area of each across the island and varied across all seasons for all habitat types except Cedar Wood. Preference varied among age and sex groups and across seasons with some groups showing opposite selection for the same cover type in different seasons. Species and diameter-class distributions of selected den trees differed from a random sample of trees across the landscape. Species composition of trees with cavities also differed from the species composition across the study area. American beech (Fagus grandifolia—relative abundance 8.7%) was over-represented in the sample of trees with cavities (29.4%) and trees selected as dens (65%); diameter at breast height (dbh) of beech den trees averaged 80.0 cm, whereas all beech trees averaged 71.2 cm. For all species combined, mean dbh of den trees was 78.4 cm as compared to trees with cavities (67.6 cm), or all trees (50.4 cm). The relative availability of large, cavity-prone tree species was related to previous logging practices.

Recent studies in Southeast Alaska suggest the ecology of Glaucomys sabrinus differs from populations in the Pacific Northwest. In Southeast Alaska, densities were the highest reported for the species, populations were not as closely linked to old-forest attributes, and individuals had a more diverse diet that was less dependent on mycophagy. Pacific Northwest communities are comprised of several arboreal rodents; Southeast Alaska has a depauperate mammal fauna. I hypothesized that Southeast Alaska populations had a broader realized niche because of competitive release. The red squirrel (Tamiasciurus hudsonicus) is the only other arboreal squirrel and it is absent from the southern outer islands of Southeast Alaska’s Alexander Archipelago. I compared demography and body mass of G. sabrinus on Prince of Wales Island to a population in sympatry with T. hudsonicus on a separate island (Mitkof). Home ranges were larger and population density, breeding female density, and juvenile recruitment of G. sabrinus were all lower in sympatry with T. hudsonicus. In a companion study, G. sabrinus on Prince of Wales Island used cavities for denning relatively more frequently than in sympatry with T. hudsonicus on Mitkof Island. Female G. sabrinus depend on cavities for natal dens, and breeding female and population densities are positively correlated with large snag or tree density. The presence of T. hudsonicus may influence G. sabrinus populations by limiting availability of cavities. Furthermore, variation in vertebrate assemblages among islands may influence realized niches of resident species, which manifest unique demographic profiles compared to populations of different ecological communities.

Discerning the intricacies of mating systems in butterflies can be difficult, particularly when multiple mating strategies are employed and are cryptic and not exclusive. We observed the behavior and habitat use of 113 male Taylor’s checkerspot butterflies (Euphydryas editha taylori). We confirmed that two distinct mating strategies were exhibited; patrolling and perching. These strategies varied temporally in relation to the protandrous mating system employed. Among perching males, we recorded high site fidelity and aggressive defense of small (

Research on the impact of clearcut logging and partial harvesting practices on northern flying squirrels (Glaucomys sabrinus) has shown inconsistent and contrary results, limiting the use of this species as a management indicator species. Much of this variability in study results is due to the labor intensive nature of studying flying squirrels, resulting in small sampling sizes (average ¼ 5.2 sites, n ¼ 14) and high variation (CV ¼ 0.59) across studies. We conducted a meta-analysis of relevant studies from North America to determine how forestry practices affect flying squirrel abundance. Mean effect size was � 1.18 (P < 0.001; n ¼ 14) for all studies, indicating a strong difference between control stands and those regenerating postclearcut or following partial harvesting. Our results support the association of northern flying squirrels with mature, uncut forest and their suitability as ecological indicators of these vegetation types. 2011 The Wildlife Society.

Densely vegetated environments have hindered collection of basic population parameters on forest-dwelling ungulates. Our objective was to develop a mark—recapture technique that used DNA from fecal pellets to overcome constraints associated with estimating abundance of ungulates in landscapes where direct observation is difficult. We tested our technique on Sitka black-tailed deer (Odocoileus hemionus sitkensis) in the temperate coastal rainforest of Southeast Alaska. During 2006–2008, we sampled fecal pellets of deer along trail transects in 3 intensively logged watersheds on Prince of Wales Island, Alaska. We extracted DNA from the surface of fecal pellets and used microsatellite markers to identify individual deer. With genotypes of individual deer, we estimated abundance of deer with moderate precision (±20%) using mark—recapture models. Combining all study sites, we identified a 30% (SE = 5.1%) decline in abundance during our 3-year study, which we attributed to 3 consecutive severe winters. We determined that deer densities in managed land logged >30 years ago (7 deer/km2, SE = 1.3) supported fewer deer compared to both managed land logged

We studied responses of Columbian white-tailed deer (Odocoileus virginianus leucurus) to cattle and sheep in western Oregon because of viability concerns. We used radio-telemetry, observations from horseback, and searches with a trained dog to determine fawning habitat, dam home ranges, and habitat use by fawns. Dams (n = 12) shifted ( = 366 m, P < 0.05) their center of activity by establishing disjunct areas of use prior to fawning. Ten dams exhibited their largest Euclidian movement during May—July; 7 females undertook extended ( = 1445 m) forays during spring. Three natal sites averaged 1926 m from the center of the dam's annual home-range. Dams avoided (P < 0.05) areas with livestock during fawning; 3 fawns were encountered during 243 h of searching (1 fawn/91.4 h) in areas with livestock stocking levels of ≥2.5 animal use month/ha (AUM), whereas 39 fawns were encountered during 275 h of searching (1 fawn/7.1 h) in areas with

We studied den use and den-habitat selection by the Prince of Wales Island flying squirrel (Glaucomys sabrinus griseifrons) at multiple spatial scales in fragmented temperate rain-forest habitats because of the role dens play in the distribution, reproduction, and population density of this endemic subspecies. We observed differences in spatial patterns associated with den use between juveniles and adults: juvenile core denning areas were almost an order of magnitude larger than those of adults, and juveniles used about one-half the number of dens per month as adults. Female juveniles exhibited both the largest mean and maximum movements between consecutive dens among all age and sex classes. At the microhabitat scale of den selection snags were not selected over live trees, but flying squirrels primarily used cavities in snags and live trees. Flying squirrels also selected dens in the largest diameter live trees and snags, in snags with intermediate levels of decay, in live trees with more conks and visible bole entries, and in western hemlock (Tsuga heterophylla). At the broader scale of den selection flying squirrels chose den locations in neighborhoods with higher-volume forests and lower levels of fragmentation, although not lower absolute amounts of edge, than was available across the landscape. Our results suggest that extensive modification of landscapes from clear-cut logging and the creation of an early-seral matrix appeared to influence spatial patterns of den use in flying squirrels and den selection at the broader scale. When compared to patterns in a more-intact landscape, den selection at the microhabitat scale did not relate to differences in landscape context, suggesting additional factors might play an important role in den use across the region.

Where dispersal is energetically expensive, feeding and food availability can influence dispersal success. The endemic Prince of Wales northern flying squirrel (Glaucomys sabrinus griseifrons) inhabits a landscape mosaic of old-growth, 2nd-growth, and clear-cut stands, with the latter 2 representing energetically expensive habitats. We estimated the diet of flying squirrels using stable isotope and fecal analyses, determined whether food availability varies among forest stands, and assessed the likelihood of foraging across a managed landscape given the distribution of foods on Prince of Wales Island (POW), Alaska. Both stable isotope and fecal analyses revealed that conifer seeds, lichens, and fungi were the main dietary items consumed and assimilated by flying squirrels. Similarly, soil macroinvertebrates were consumed by squirrels, whereas berries were not. Nonetheless, although examination of stable isotope data suggested that squirrels assimilated few nutrients from truffles, this food source was among the most frequent diet items in feces, probably because flying squirrels assimilate elements other than nitrogen from fungi. Our surveys showed that conifer seeds, truffles, and lichens were more prevalent in old-growth than 2nd-growth and clear-cut habitats. Thus, our results indicate that diet and availability of food items on POW may influence foraging success and dispersal movements of G. sabrinus across fragmented landscapes because of limited availability of food resources in the managed habitats. DOI: 10.1644/09-MAMM-A-014R.1.

Although dispersal is an important attribute of animal population ecology, knowledge of dispersal rates or distances for many wide-ranging species is lacking. Current methods require capturing and restraining animals, which can be costprohibitive, fail to collect sufficient samples or change animal ranging behaviors. Herein, we describe a novel, cost-effective and non-invasive method, using bait enriched with stable isotopes to mark the hair of American martens Martes americana. Captive martens that consumed isotopically labeled glycine exhibited significant and progressive enrichment in the isotopic signature of 13 C, 15 N and 2 H in both whole blood and hair. A distinct mark in hair, 42 standard deviations above natural abundance, occurred within 14 days of the second dose. The rate of isotopic labeling of hair was higher in spring, possibly because labeled amino acids became diluted among the many hairs growing during the autumn. Because hair and feathers can be collected non-invasively from large geographic areas without capturing animals, this labeling method can be used to mark and study the movement and dispersal rates of animals across landscapes efficiently.

Keen's myotis (Myotis keenii) has one of the most limited geographic distributions of any species of bat in North America. Because there is little knowledge of its roosting ecology, we examined selection of day-roosts in trees by male and female Keen's myotis at 3 spatial scales (tree, tree plot, and landscape) on Prince of Wales Island, southeastern Alaska, from May to September 2006. We selected variables known to influence roost selection by other tree-roosting bats for logistic regression models. We used Akaike's information criterion to rank all models within and between scales according to their ability to differentiate between characteristics of used and available roosts and we determined the effect of each variable with model-averaged coefficient estimates and associated odds ratios. We tracked 13 females and 6 males to 62 and 24 roosts in trees, respectively. Selection of day-roosts by males and females was most strongly influenced by characteristics of trees. The odds a tree was used for roosting by female Keen's myotis increased with the presence of defects, increasing diameter, and decreasing bark; increasing quadratic mean diameter in the tree plot; and decreasing distance to the nearest stream and increasing proportion of old growth in the landscape. Male Keen's myotis exhibited flexibility in types of roosts chosen, but the odds of a tree being used increased with decreasing bark, the presence of defects, and increasing slope-height. The odds a tree was used as a roost by males also increased with the increasing proportion of trees in early to late decay stages in the tree plot. Some habitat features differed between males and females at each spatial scale and differences are likely a reflection of the energetic demands associated with reproduction. We suggest that maintaining structural components characteristic of old-growth rain forest will promote conservation of Keen's myotis in southeastern Alaska.

Successful dispersal in many species may be a function of the distance at which animals can perceive a particular landscape feature (i.e., perceptual range), as well as energetic costs associated with traversing the distance towards that feature. We used a model, relating perceptual range to body size of mammals, to predict the perceptual range of the northern flying squirrel ( Glaucomys sabrinus (Shaw, 1801)) in fragmented forests of Southeast Alaska. We hypothesized that the perceptual range of flying squirrels would be 325.5–356.5 m in clearcuts and 159.7–174.9 m in second-growth stands. The distance advantage in clearcuts may, however, be lost if the cost of transport in that habitat is higher. Our results suggest that as heuristically predicted by the model, the perceptual range of flying squirrels was greater in clearcut habitats than in second-growth stands. Nonetheless, for both habitats the actual perceptual range was significantly shorter than predicted by the model. We found that precipitation, and associated cloud cover and illumination, and wind speed, which affect olfaction capabilities, influenced orientation success. Although squirrels more often oriented towards the forest edge in clearcuts, they paused more often during their movements, which may lead to higher costs of dispersing through this habitat. The application of the mass-based model to nonagricultural landscapes should be done with caution, and variables such as wind and illumination be measured concurrently. Our data illustrate that dispersing squirrels likely will not venture into managed habitats because logging creates clearcuts larger than the perceptual range of these mammals.

A common arboreal rodent of boreal and montane coniferous forests, the northern flying squirrel (Glaucomys sabrinus) has several life-history traits typical of K-selected species. Density varies among forest types, with core areas of use centering on food patches. Density is largely limited by food, and to a lesser extent, suitable natal dens, but also is influenced by potential competitors and predators. Local abundance of G. sabrinus frequently is correlated with density of large trees and snags, shrub and canopy cover, prevalence of old-forest features (e.g., coarse woody debris), and abundance of hypogeous mycorrhizal fungi (truffles). Diet varies seasonally and among habitats, but truffles (spring and autumn) and lichens (winter) are most often reported. In some parts of its geographic range, G. sabrinus has a more diverse diet and lower reliance on truffles in forests with a depauperate arboreal small mammal community. G. sabrinus is a keystone species in the Pacific Northwest, because its diet facilitates an obligate mutualistic relationship between mycorrhizal fungi and some trees and shrubs and because it is essential prey for mesocarnivores and avian predators. G. sabrinus achieves its highest densities in old growth, but also occurs in secondary forests. Disturbance that reduces structural complexity, canopy cover, or the availability of large, decadent trees typically results in smaller populations through effects on food, den sites, or risk of predation. The fundamental niche of G. sabrinus may be broader than suggested by early research in the Pacific Northwest. Sustaining viable and well-distributed populations in heavily modified landscapes will depend on the capability of remaining forest habitat to sustain breeding populations without immigration, or functional connectivity among fragmented populations such that viable metapopulations will persist. Future research should focus on identifying habitat conditions that sustain breeding populations in modified habitats and determining whether G. sabrinus can migrate freely through a matrix of unsuitable habitat.

Habitat reserves are a common strategy used to ensure viability of wildlife populations and communities. The efficacy of reserves, however, is rarely empirically evaluated. We examined the likelihood that small (650 ha), isolated habitat reserves composed of old-growth Sitka spruce ( Picea sitchensis )–western hemlock ( Tsuga heterophylla ) rain forest (upland-OG) and mixed-conifer peatlands (peatland-MC) would sustain populations of northern flying squirrels ( Glaucomys sabrinus ) in the absence of immigration or emigration within the Tongass National Forest in Southeast Alaska. We used demographic data obtained from a study of flying squirrels on Prince of Wales Island in Southeast Alaska and litter size from flying squirrels in similar habitat to estimate per capita rate of increase ( r ) of flying squirrels in upland-OG ( r = 0.14, SD = 0.42) and peatland-MC habitats ( r = 0.01, SD = 0.39). Our results indicated that peatland-MC habitat was unlikely to sustain populations and that viability of flying squirrel populations in small habitat reserves largely depended on the upland-OG forest component. We subsequently estimated time to extinction ( T N ) based on r , its variance ( v ), and the potential population ceiling ( K ). We used T N to calculate the probabilities ( P t ) that squirrel populations would persist in small reserves containing 100%, 50%, and 25% upland-OG habitat for 25, 50, and 100 years. In each scenario, we calculated T N and P t for 2 levels of v . For the best-case scenario (100% upland-OG forest, lowest variance, t = 25 years), T N was 507 years and P t was 0.95. For the worst-case scenario (25% upland-OG forest, highest variance, t = 100 years), T N was 237 years and P t was 0.66. Minimum patch size of upland-OG forest required for a high probability ( P t = 0.95) of sustaining a flying squirrel population in isolation with relatively low demographic variability ( v = 0.34) for 25, 50, or 100 years was 578, 5077, and 78,935 ha, respectively. We concluded that it was unlikely that small isolated habitat reserves could sustain populations of flying squirrels for >25 years in the absence of immigration. Consequently, dispersal among small reserves is critical to ensure that they function to support metapopulations of northern flying squirrels.

We assess locomotor performance by northern flying squirrelsGlaucomys sabrinus Shaw, 1801 and test the hypothesis that gliding locomotion is energetically cheaper than quadrupedal locomotion. We measured 168 glides by 82 northern flying squirrels in Alaska. Mean glide distances varied from 12.46 m to 14.39 m, with a maximum observed glide distance of 65 m. Mean glide angles varied from 41.31° to 36.31°, and mean air speed ranged from 6.26 m/s to 8.11 m/s. There were no differences in the performance of male and female flying squirrels. We used models of transport cost to provide an initial assessment of the hypothesis that gliding locomotion is energetically less expensive than quadrupedal locomotion. For glides of average length, cost of gliding was less than cost of quadrupedal locomotion except when the animals climbed to the launch point very slowly or ran quickly. Thus the hypothesis that gliding is less expensive than quadrupedal locomotion is supported.

Whether land management planning provides for sufficient habitat to sustain viable populations of indigenous wildlife is one of the greatest challenges confronting resource managers. Analyses of the effects of land management on natural resources often rely on qualitative assessments that focus on single species to reflect the risk of wildlife extinction across a planning area. We propose a conceptual framework for sustainable management of wildlife habitat that explicitly acknowledges the greater risk of an extinction event when considering the viability of multiple species, e.g., an indigenous vertebrate fauna. This concept is based on the principle that the likelihood of at least one event (i.e., species extinction) is the joint probability of the extinction probabilities of individual species, assuming independence among species` responses to disturbance. We present an ecological rationale to support the view that, at a spatial scale of 104-106 ha (i.e., planning area) and a temporal scale of 102 years (i.e., planning horizon), wildlife species operating at varying ecological scales respond relatively independently to disturbances typically associated with land management. We use a hypothetical scenario of a wildlife viability assessment and Monte Carlo simulation to demonstrate that the probability of `any extinction` is consistently higher than the probability of the `single most likely` extinction, and that the difference between these values increases as more disturbance-sensitive species (i.e., species at risk) are analyzed. We conclude that risk assessments that rely upon the most sensitive single species may substantially underestimate the risk of wildlife extinction across a planning area. Furthermore, the selection of a planning alternative based on relative threat of local extinction of wildlife populations can vary depending on which paradigm is used to estimate risk to viability across the planning area.

Management indicator species (MIS) often are selected because their life history and demographics are thought to reflect a suite of ecosystem conditions that are too difficult or costly to measure directly. The northern flying squirrel (Glaucomys sabrinus) has been proposed as an MIS of temperate rain forest of southeastern Alaska based on previous studies in the Pacific Northwest that demonstrated its habitat is multi-factorial, i.e., an emergent property of old-growth forest. We evaluated the suitability of flying squirrels as MIS in temperate rain forests of Alaska by modeling seasonal (spring, autumn) microhabitat use with stepwise logistic regression (SLR) using either individual habitat variables (n = 26) or multivariate habitat "factors," which were linear combinations of individual habitat variables generated from factor analysis. We compared the efficacy of single variable vs. multivariate factor models in explaining variation in microhabitat use to test the hypothesis that the habitat of flying squirrels in southeastern Alaska was an emergent property of old-growth rain forest. The underlying premise was that if factors were more thorough in explaining microhabitat use, the habitat of flying squirrels was multifactorial; that is, it consisted of multiple late-seral forest attributes occurring coin- cidentally at usable spatial scales (e.g., home range). SLR models with multivariate factors performed poorer in predicting capture sites than models of individual habitat variables. Two variables, density of large (>74 cm dbh) trees and understory cover of Vaccinium, explained much of the variation in microhabitat use. We conclude that the habitat of G. sabrinus in southeastern Alaska does not reflect emergent properties of old-growth forest in southeastern Alaska and hypothesize that this pattern may be related to regional ecological differences that facilitate a more general lifestyle than populations in the Pacific Northwest. Furthermore, the effectiveness of Glaucomys sabrinus as an MIS in north temperate rain forest is suspect, illusstrating that regional differences in ecology of a species warrant caution when considering the suitability of MIS among geographic areas.

We review results and implications from recent wildlife studies that followed from the 1997 Tongass Land Management Plan (TLMP) and identify information needs and directions for research, development, and application. Sustained population viability of wildlife species was identified as a major issue in the TLMP planning process. Several species were identified as management indicator species, and research was conducted to determine their potential sensitivity to forest management. Southeastern Alaska was found to be a region with an especially high degree of endemism in its small mammal fauna, principally because of the combination of its archipelago geography combined with highly dynamic glacial history. Two species of endemic small mammals selected for demographic study, however, appeared to be less dependent on old-growth forests than had been suspected at the time TLMP was written: the northern flying squirrel ( Glaucomys sabrinus ) because of relatively high suitability of noncommercial, low-volume, mixed-conifer forest; and the southern red-backed vole ( Clethrionomys gapperi ) because of relatively high suitability of precommercially thinned young-growth forest. The northern goshawk ( Accipiter gentilis ) was found to be problematic for “management indicator” status because of logistical difficulties involved in monitoring this relatively rare, highly mobile species that frequently changes nest sites. Sampling protocols were developed for marbled murrelet ( Brachyramphus marmoratus ), although murrelet populations do not appear to be in trouble on the Tongass. The conservation strategy of TLMP for American marten ( Martes americana ) appeared to be sound on Chichagof Island where marten have been studied intensively, but implications for the rest of southeastern Alaska were unclear without further work. Studies of the Alexander Archipelago wolf ( Canis lupus ligoni ) indicated that population density of black-tailed deer ( Odocoileus hemionus ) and road access (to wolf hunters) were the predominant factors affecting wolf productivity and mortality, respectively. Finally, studies of bird community response to timber-harvest alternatives to clearcutting indicated that although creation of forest “edge” may increase nest predation rates, the actual response depends on a broad array of factors and is highly variable. We suggest that research, development, and application focus on plant and animal communities and management of vegetation to achieve specific objectives for wildlife habitat. We suggest that such efforts emphasize silviculture of second-growth forests, understanding old-growth reserves, distribution of endemic small mammals, and alternatives to clearcutting. Models for evaluating black-tailed deer habitat and populations are needed for subsistence-hunting management, and some work needs to be directed at interactions between tourism and selected wildlife species.

The dynamic geological history and naturally fragmented landscapes of southeastern Alaska create an environment with a high potential for endemism. The temperate rainforest of the region regenerates and develops slowly, and old-forest characteristics do not appear until ≥300 years following disturbance. The challenges of managing forest resources are intensified in island archipelagos because of the increased sensitivity of indigenous biota to disturbance and higher rates of extinction, especially among endemic organisms. Early expeditions of the large islands of the Alexander Archipelago (≈1% of all named islands) documented 27 endemic mammalian taxa. More recent studies with modern techniques found that some reputed endemics showed nominal levels of genetic divergence from other conspecific populations, but more divergence existed among several taxa than was reflected in the current taxonomy. Furthermore, the mammal fauna of southeastern Alaska has a nested structure with complex phylogeographic patterns suggesting multiple colonization events. Of eight taxa examined through phylogeographic analyses, five species showed acute genetic variation and divergence in mitochondrial sequences. Four species were comprised of coastal and continental clades (i.e. populations of recent common descent), whereas the fifth species showed a third clade. Conversely, the northern flying squirrel (Glaucomys sabrinus) and southern red-backed vole (Clethrionomys gapperi) were represented by relatively shallow divergent lineages. Still, G. sabrinus showed a distinct mitochondrial lineage on 11 islands (Prince of Wales Island complex), which exhibited severely reduced genetic variation. Moreover, flying squirrels in southeastern Alaska are genetically distinct from populations in the Pacific Northwest; as different as each is from the southern flying squirrel (G. volans). Recent ecological studies of endemic populations of the northern flying squirrel and the southern red-backed vole (reputed old-growth associates) suggest that risk of extirpation in managed landscapes is likely less than was presumed during recent land management planning in the region because: (1) abundant noncommercial forests apparently contribute to breeding populations of northern flying squirrels, which appear to have a more general lifestyle than populations in the Pacific Northwest; and (2) red-backed vole populations may be able to exist in managed young-growth stands that originated from clearcut logging. Still, there are essential questions for both species regarding the influence of annual population fluctuations on habitat distribution and population demography, stand and landscape features that restrict dispersal, and vegetative and structural characteristics of second-growth stands that will sustain breeding populations of both species.

We studied habitat relations of the Prince of Wales flying squirrel (Glaucomys sabrinus griseifrons), an endemic of the temperate, coniferous rainforest of southeastern Alaska, because of concerns over population viability from extensive clear-cut logging in the region. We used stepwise logistic regression to examine relationships between microhabitat use (i.e., captures among traps spaced at 40-m intervals) and 26 vegetative and structural habitat features measured in plots centered on trap stations. Seasonal (spring, autumn) models were created for two oldgrowth forest types: upland, western hemlock (Tsuga heterophylla)‐Sitka spruce (Picea sitchensis) forests (upland-OG); and peatland-scrub‐mixed-conifer forests (peatland-MC). Density of trees with diameter at breast height (dbh) .74 cm and abundance of Vaccinium were positively correlated with microhabitat use in peatlandMC during both seasons. During spring and autumn, the odds of capturing a flying squirrel increased by factors of 2.7 and 16.9, respectively, with an increase in mean density of 10 large trees/ha. Microhabitat use of uplandOG during autumn was positively correlated with density of snags with a dbh of 50‐74 cm and negatively correlated with percentage cover of understory herbaceous vegetation; microhabitat use during spring was inversely correlated with percentage surface cover of water. At the macrohabitat (13-ha replicate of forest type) scale, large (.74-cm dbh) trees explained 65% of the variation in density between forest types; percent cover of moss and volume of down wood in decay classes I‐IV explained 70% and 63‐77% of the variation, respectively. Our findings corroborate general patterns reported for western coniferous forests, but suggest that G. sabrinus in temperate rainforests of southeastern Alaska differ ecologically from populations in the Pacific Northwest in important ways.

We studied demography of the Keen’s mouse (Peromyscus keenimacrorhinus) and the Wrangell Island red-backed vole (Clethrionomys gapperi wrangeli) in the Alexander Archipelago during 1998–2000 because of concerns over population viability from extensive clear-cut logging of temperate rain forest in the region. We trapped 1-ha grids and assessment lines with live traps during spring and autumn to compare populations among gap-phase oldgrowth, multicohort old-growth, peatland mixed-conifer, and thinned young-growth (23-year-old) forests. Generally, gap-phase old growth and peatland mixed conifer supported the highest and lowest populations of voles, respectively. One notable exception was during autumn 1998, when vole population levels were highest and density was higher (P , 0.02) in young growth than gap-phase old growth. Mean body mass, minimum summer and overwinter survival, age and sex composition, and percentage reproductive females did not differ among habitats. For Keen’s mouse, density was highest in 1998; overall, populations were highest in young growth and lowest in peatland mixed conifer. Mean body mass and minimum summer and overwinter survival did not differ among habitats, but fewer reproductive females were recorded in multicohort than in gap-phase old growth, peatland mixed conifer, or young growth. Our results suggest that C. gapperi populations in southeastern Alaska are not as sensitive to canopy removal as has been indicated elsewhere in western coniferous forests and that P. keeni populations in southeastern Alaska flourish in a variety of habitats. If the results of our study can be generalized across southeastern Alaska, peatland mixed conifer likely contributes little to breeding populations of C. gapperi and thus is unlikely to mitigate any effects of broad-scale clear-cut logging of old-growth forests.

We studied the Prince of Wales flying squirrel (Glaucomys sabrinus griseifrons) in temperate rain forest of southeastern Alaska to provide the 1st quantitative estimates of demography from southeastern Alaska and test predictions of the hypothesis that Sitka spruce (Picea sitchensis)–western hemlock (Tsuga heterophylla) forest is primary habitat for G. sabrinus in southeastern Alaska. We expected that abundance, body condition, productivity, and summer and overwinter survival of G. sabrinus would be higher in spruce–hemlock forest (which typically are the old-growth forests of upland sites [upland-OG]) than in peatland-scrub–mixed-conifer (peatland-MC) forest. Mean values of minimum number of animals known alive and density during autumn were higher in upland-OG than in peatland-MC, and both were about 2 times higher than corresponding spring values. Age and sex composition of the population was similar among years, between seasons, and between habitats. Males comprised a larger portion of the po...

American black bear (Ursus americanus) populations were significantly reduced throughout their range, particularly in southeastern North America. Currently, populations in this region are very fragmented, resulting in concern over possible barrier effects of rivers to normal bear movements and dispersal. This is particularly true for Mississippi, where black bear dispersal into the state is critical if populations are to be recovered. Thus, we studied the relative effects of rivercourses on bear movements and dispersal patterns in southeastern Arkansas, 1992–1996. We captured, radiocollared, and uniquely tagged 40 bears and used radiotelemetry to determine their movements. The Mississippi River (width ≈1600 m) deflected bear movements, whereas the White River (width ≈200 m) was not a barrier to bear movements or dispersal patterns. Frequency of river crossing differed by gender (P=0.007) and season (P

We examined the effects of white-tailed deer (Odocoileus virginianus) browsing and canopy opening size on relative abundance and diversity of woody and herbaceous regeneration in various sized forest openings in a southern bottomland hardwood forest over three growing seasons (1995–1997). We created 36 canopy openings (gaps), ranging from 7 to 40 m in radius, by group selection timber harvest in December 1994. Fenced exclosures were constructed in the center of each gap and vegetation was sampled monthly from April to September. Plant species richness, diversity, evenness, relative abundance, and a browsing index were calculated for each gap size and for each exclosure type. Herbaceous richness, diversity, or evenness did not differ among exclosure types in any year of the study. Browsing index was higher in the controls in 1996 and 1997. Browsing index for woody species was highest in the controls in 1995 and 1997. Relative abundance of herbaceous species was highest in the 29 m gap size in 1997. Richness and diversity of woody species were lowest in the 29 m gap size in 1995 and 1996. Overall browsing rates on both woody and herbaceous vegetation were low throughout all the 3 years of the study. Low browsing rates reflect seasonal changes in habitat use by deer. Because of the low rates of browsing, vegetative differences among exclosure treatments and gap sizes likely are not attributable to deer herbivory. Other factors, such as soil disturbance, may have influenced the initial vegetative response more than herbivory or gap size.

We radiotagged seven female and two male Marbled Murrelets (Brachyramphus marmoratus) of undetermined breeding status and followed their movements through the inner passages of northern southeast Alaska during the breeding season (May–July) in 1998. Six of the nine murrelets were detected inland in the early morning hours from 24 June to 17 July. Inland visits for each individual were consistent to a particular location, but short in duration, which precluded locating nest sites. We recorded 46 locations at sea up to 124 km (x̄ = 78 ± 27 km) from inland sites during the period 19 June to 16 July. We detected murrelets at inland sites and at sea on the same day on 20 occasions with a mean distance between these locations of 75 ± 42 km. The majority of murrelets were located at sea in western Icy Strait, a productive feeding area at the mouth of Glacier Bay, Alaska. This study provides the first direct evidence that Marbled Murrelets in southeast Alaska are consistently traveling considerable distances between potential nesting and foraging areas. These findings have important implications for murrelet conservation and management efforts in southeast Alaska.

Home range size of six swamp rabbits in south-central Arkansas was estimated by radio-telemetry from February 1991 through March 1992. The average home range size was significantly larger than previously reported estimates. This difference is partly attributable to the large number of observations per rabbit in our study, but may also be explained by our inclusion of numerous locations of swamp rabbits during periods of deep inundation. All of the individual rabbits tracked used different areas when the study site was flooded. These results provide the first quantitative description of the response of swamp rabbits to flooding.

We examined spring and summer use of woody browse by white-tailed deer (Odocoileus virginianus) in forest gaps created by group selection timber harvest in a South Carolina bottomland hardwood forest during 1995 and 1996. Percent available twigs browsed, relative abundance, and relative use were calculated for each species with more than 50 twigs sampled. We used chi-square analysis to rate species as preferred, proportional, or low use. Total percent browsed was low in both years (2.5% in 1995; 3.0% in 1996). In 1995, 6 species were rated as high use, 4 species as proportional use, and 10 species as low use. In 1996, 6 species were rated as high use, 7 as proportional use, and 9 as low use. Species ratings generally were in agreement with other food habits studies in the Southeast. Preferred browse species included red maple (Acer rubrum), winged elm (Ulmus alata), greenbrier (Smilax spp.), and black willow (Salix nigra). The low rates of browsing probably were due to low use of the study area by deer during the growing season. Deer browsing likely had little impact on regeneration of most species in this bottomland hardwood forest. South. J. Appl. For. 23(2):78-82.

Papers in this Special Feature were presented at a symposium on the biology of Glaucomys sabrinus convened at the 86th Annual Meeting of the American Society of Mammalogists in June 2006. Because G. sabrinus is an arboreal species that relies on several attributes of older forests, it is an ideal model organism for studying impacts of broad-scale habitat loss and alteration from logging, clearing, and natural disturbances. The objective of the symposium was to integrate knowledge of mammalogists from multiple disciplines to achieve a more complete biological portrait to gain insights about how forest communities are being impacted by dramatic changes in forest composition and distribution following European settlement of North America, and to identify gaps in knowledge and information needs that can guide future research. The symposium included 5 papers that encompass a diversity of biological information, including the evolutionary origin and systematics of Glaucomys, the anatomy and evolution of G. sabrinus, its biogeography, genetic variation within and among regional populations, its ecology, functional morphology, kinetics, and issues and challenges of conservation.

The density of active nests of bald eagles Haliaeetus leucocephalus decreased with increasing proximity to clearcuts; nesting success (number of chicks/nest) did not vary with density and proximity to clearcuts. Our results indicate that buffer zones around eagle nests probably should be at least 300 m wide to maintain eagle nesting density. Still wider buffers might be needed to include adequate alternative nest sites and perch trees, but the optimal width of the buffer strip may vary with other locally important factors, such as food availability.

Three different types of forests (mature, mixed upland, and cut-over) in central Arkansas were surveyed in June and October 1991 and February and May 1992 for latrines of swamp rabbits ( Sylvilagus aquaticus ). Swamp rabbits deposited >91% of their fecal pellets on logs. A greater density of pellets were found in February 1992 compared to other months. Length, height, diameter, decay class, and percent cover of moss on logs used as latrines by swamp rabbits were recorded. Logistic regression was used to predict the likelihood that a log would be used as a latrine. Increasing decay class, percentage cover of moss, and diameter of logs were correlated with latrines of swamp rabbits. Height of logs did not distinguish between used and unused logs, but length and season were significant predictors of use of logs as latrines in forests of mature bottomland hardwood and cut-over bottomland. Spatial clumping of latrines and peak use during breeding were consistent with the hypothesis that latrines on logs serve as territorial markers. An alternative hypothesis that swamp rabbits elevated themselves on logs to increase their field of view and coincidentally deposited pellets on logs was tested experimentally with three obstruction treatments; visual + physical, only physical, and a control. Treatments were placed on 1-m sections of 54 logs that had been used as latrines in at least 2 of the 4 monthly surveys. Surveys conducted for 4 months after the installation of obstructions showed a significant interaction between use of a log as a latrine, treatment type, and month of survey.

We tested the premise that rates of visitation by raccoons ( Procyon lotor ) to scent stations vary directly with population density by manipulating the density of an island population of this carnivore in middle Tennessee. Despite its widespread use, the scent-station index to population size has not been validated. General protocol for scent stations followed previous investigators; radiotelemetry was used to monitor individual behavior of raccoons. We determined minimum population size from the records of known captures and compared them with visits to scent stations recorded twice monthly during an initial period with no manipulation (May 1987–August 1988); similar procedures were used during an experimental period (September 1988–August 1989) when raccoons were removed and held on the mainland for ca. 1 month during each season and then returned to the island. Abundance of raccoons on the island ranged from 32 to 42 when estimated twice each month; computed indices of relative abundance varied from zero to 286. Rates of visitation by raccoons were highest in spring and summer during both the baseline and experimental period. Visits to scent stations were independent of density throughout the study. During the experimental period, both the largest and smallest observed indices of relative abundance occurred when an estimated 25% of the population had been removed and when all known animals ( n = 40) occurred on the island. Local fluctuations of populations may precipitate changes in behavior of raccoons that preclude the use of scent stations to index abundance, particularly in heterogeneous habitats.

Transportation corridors (notably roads) affect wildlife habitat, populations, and entire ecosystems. Considerable effort has been expended to quantify direct effects of roads on wildlife populations and ecological communities and processes. Much less effort has been expended toward quantifying indirect effects. In this report, the authors provide a comprehensive review of road/transportation corridor ecology; in particular, how this new field of ecology has advanced worldwide. Further, they discuss how research thus far has shaped the understanding and views of the ecological implications of transportation infrastructures, and, in turn, how this has led to the current guidance, policies, and management options. The authors learned that the impacts of transportation infrastructures are a global issue, with the potential to affect a wide variety of taxonomically diverse species and ecosystems. Because the majority of research to date has focused on the direct and more aesthetic and anthropocentric implications of transportation corridors, mainly wildlife-vehicle collisions, it is a fairly standard practice to incorporate underpasses, green bridges (i.e., overpasses), fencing, and barriers into road corridors to alleviate such impacts. Few studies, however, have been able to demonstrate the efficiency of these structures. Furthermore, it is becoming increasingly evident that the indirect implications of transportation infrastructures (i.e., behavioral responses of wildlife individuals to roads) may be more pervasive, at least from the standpoint of biological diversity. Understanding how road corridors influence the functional connectivity of landscapes is crucial if species of concern are to be effectively managed. With these issues in mind, the authors propose a program of study that addresses the indirect and cumulative implications of transportation infrastructure on species distributions, community structure and ecosystem function.

Gliding allows mammals to exploit canopy habitats of old-growth forests possibly as a means to save energy. To assess costs of quadrupedal locomotion for a gliding arboreal mammal, we used open-flow respirometry and a variable-speed treadmill to measure oxygen consumption and to calculate cost of transport, excess exercise oxygen consumption, and excess post-exercise oxygen consumption for nine northern flying squirrels (Glaucomys sabrinus) and four fox squirrels (Sciurus niger). Our results indicate that oxygen consumption during exercise by flying squirrels was 1.26-1.65 times higher than predicted based on body mass, and exponentially increased with velocity (from 0.84 ± 0.03 ml O(2) kg(-1) s(-1) at 0.40 m s(-1) to 1.55 ± 0.03 ml O(2) kg(-1) s(-1) at 0.67 m s(-1)). Also, cost of transport in flying squirrels increased with velocity, although excess exercise oxygen consumption and excess post-exercise oxygen consumption did not. In contrast, oxygen consumption during exercise for fox squirrels was similar to predicted, varying from 0.51 (±0.02) ml O(2) kg(-1) s(-1) at 0.63 m s(-1) to 0.54 (±0.03) ml O(2) kg(-1) s(-1) at 1.25 m s(-1). In addition, the cost of transport for fox squirrels decreased with velocity, while excess exercise oxygen consumption and excess post-exercise oxygen consumption did not. Collectively, these observations suggest that unlike fox squirrels, flying squirrels are poorly adapted to prolonged bouts of quadrupedal locomotion. The evolution of skeletal adaptations to climbing, leaping, and landing and the development of a gliding membrane likely has increased the cost of quadrupedal locomotion by >50% while resulting in energy savings during gliding and reduction in travel time between foraging patches.