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Structural enrichment in commercial tree plantations is a potential tool to increase snag numbers but relatively little information is available about how species, size, and spatial distribution of created snags are associated with longevity of these structures. We created 1197 snags in 31 harvest units from 1997 to 1999 in the Cascade and Coast Ranges, Oregon, USA, by topping live trees with harvesting equipment. We used an experimental design to distribute created snags at three densities and as either single or clumped created snags. We fit Weibull and log-logistic Accelerated Failure Time models and found that the median failure time was insensitive to the choice of distribution. We found a small positive effect of diameter at breast height (DBH) and a slight negative effect of increasing distance between created snags on survival. Assuming Weibull and log-logistic distributions at mean observed values of DBH and distance between snags, median survival times for Douglas-fir (Pseudotsuga menziesii) were 21.0 (95% confidence interval: 19.3, 22.8) years and 21.2 (19.7, 22.8) years, respectively. For western hemlock (Tsuga heterophylla), median survival times were 13.0 (11.9, 14.2) years and 12.5 (11.4, 13.7) years, respectively. Although the two failure distributions had similar median failure times, the log-logistic implies a higher survival probability over time for snags that remained standing at the end of the study period. Created snags can be a useful supplement for harvest units rotated at ∼45 years and Douglas-fir will be available for longer as standing structures. For example, under the log-logistic model, a predicted 5% of Douglas-fir snags are retained to rotation age, so that 40 snags per hectare would be required at harvest to maintain 2 snags per hectare through stand rotation. Snags created from western hemlock will provide an early rotation pulse but are unlikely to last longer than 20 years. Our results suggest that longevity can be increased by maximizing the snag size within the safety constraints of harvesting equipment. Scattering of snags may have a slightly negative effect on snag survival but this outcome should be weighed against potential ecological benefits of variation in snag distributions.

Hunting is an integral part of North American cultures, providing a powerful connection to the outdoors for millions of people and generating billions of dollars to local and national economies. Socially, hunting has been part of hominid cultures since very early in the fossil record; a tradition that contemporary North American hunters tend to pass down to subsequent generations through family and community networks. The 13.7 million American hunters and 2.1 million Canadian nature-recreationists spend more than $38.3 billion and $1.8 billion, respectively, on non-commercial hunting-related expenses each year. Hunting activities also yield hundreds of thousands of jobs and billions of dollars in tax and other revenues in both countries. The contributions of hunters serve as the fundamental foundation for a social and economic support system for conserving wildlife and habitats for future generations.

Mitigating impacts of wind energy development on wildlife is important for conservation and public acceptance of this energy source. We provide an overview of approaches to mitigate impacts of onshore wind energy development on wildlife, following steps in the mitigation hierarchy, including avoidance, minimization, and compensatory mitigation. Planning and avoiding predicted high-risk areas is fundamental to reduce impacts on birds and bats. Contrary to avoidance, once facilities are built, options to minimize impacts need to be tailored to species at the specifc site, and can be limited especially for bats. Curtailing wind turbine operations is the only approach proven effective at reducing bat mortality. While curtailment may in part also be effective for birds, micro-siting and repowering also are likely to reduce mortality. Compensation should be considered only as part of the mitigation hierarchy when unforeseen or unavoidable impacts remain. Offsite habitat-based compensatory measures may provide the best offsets for incidental bird and bat mortality. While the conceptual framework and predictive modelling for compensatory measures are well-established, empirical evidence demonstrating effectiveness and achievement of no-net loss for wildlife populations is lacking. Similarly, few studies have evaluated effectiveness of minimization measures and other forms of mitigation. Evaluating effectiveness of preconstruction wildlife assessments and habitat modeling in predicting wildlife mortality at wind facilities remains a research need. Additionally, lack of population data for many species of wildlife hinders knowledge of population-level impacts and effectiveness of mitigation measures. Policy revisions and regulation may be necessary, especially when wildlife agencies have little or no authority in decision-making or no protection for wildlife beyond voluntary measures.

Managers of landscapes dedicated to commodity production require information about how alternative practices can promote retention of native biological diversity. Retaining or creating structural features (e.g., snags or downed logs) needed to fulfill life history requirements may benefit populations and communities. However, demographic responses of species to alternative practices have received little research attention. We tested nest survival of cavity-dependent birds in response to experimental structural enrichment by creating snags on 28 plots, Oregon, USA, 2008–2010. Each plot represented one of six combinations of created snag density (0.5, 1, and 2 snags/ha) and spatial dispersion (clumps of 5–7 snags or dispersed individual snags). We monitored 506 nests built by 10 species; three species nested in sufficient numbers for analysis. Chestnut-backed chickadee Poecile rufescens nest success was highest in the medium density clumped created snag treatment (average proportion of successful nests = 0.76; 95% CI = 0.61–0.87) and lowest in the low density clumped treatment (average proportion of successful nests = 0.39; 95% CI = 0.20–0.62). We did not find a response of either house wren Troglodytes aedon or northern flicker Colaptes auratus nest success to the experimental treatments. Period survival rates were 0.57 (95% CL: 0.39–0.72) for CBCH; 0.71 (95% CL: 0.51–0.84) for HOWR; and 0.59 (95% CL: 0.34–0.77) for NOFL. Our study suggests that creating snags in commercial harvest units is an effective practice for increasing structural complexity and supporting nesting communities of cavity-dependent birds. While leaving either clumped or dispersed created snags at a density of ∼1 ha should support nest survival rates that are similar to those reported from unmanaged forests, we emphasize that this type of structural enrichment is not a panacea for species that require very large snags or snags that occur under complex forest canopies. Retention of existing structural features in reserve areas may be an appropriate practice for conserving species with nesting requirements that differ from those we evaluated in our study.

Landscape composition may have a substantial influence on species use of habitat at local scales and effectiveness of structural enrichment practices (e.g., augmenting existing amounts of snags or downed logs). If sufficient mature (i.e., cavity containing) habitat exists at the landscape scale, cavity nester demand for nest sites could be reduced due to the surplus of existing sites ( habitat surplus hypothesis ). Alternatively, if mature forest acts as source habitat for cavity nesters, increased amounts of mature forest in the landscape will inflate the demand for snags in clearcuts ( habitat source hypothesis ). In Oregon, USA, we evaluated cavity nesting bird colonization of experimentally created snags distributed across a gradient in amount of mature forest at the landscape scale. We sampled 28 plots, each of which represented one of six combinations of created snag density (∼0.5, 1, and 2 snags/ha) and spatial dispersion (clumps of 5–7 snags or dispersed individual snags). We tested whether early successional and mature forest species groups responded differently to plot-level treatments and if the percentage of mature forest (>40 years old) within a 1000 m radius surrounding each experimental plot influenced this response. Mature forest species more readily colonized created snags as the percentage of mature forest declined in the landscape, supporting the habitat surplus hypothesis . Estimated use by mature forest species increased from 7% to 17% as percent mature forest in the landscape declined from 58% to 13% (estimated for average levels of created snag density, 0.4 snags/ha, and a spatial distribution of 45 m). Colonization of snags by early seral species also increased with decreasing mature forest (from 3% to 9%), which may support the habitat source hypothesis . Our study suggests that creating snags in commercial harvest units is an effective practice for increasing structural complexity and maintaining nesting communities of cavity-dependent birds. At the local level, created snags should be spaced as widely as possible within individual harvest units. However, our results indicate that effectiveness of snag creation will be highest in the most intensively managed landscapes where the amount of structurally diverse habitat is limited.

Evaluating spatial and temporal variation in abundance due to anthropogenic and environmental disturbances is a central aspect of wildlife ecology and management. We conducted an experiment to evaluate the effects of salvage logging on the abundance of 22 avian species and 6 foraging guilds in lodgepole pine (Pinus contorta) forests affected by beetle outbreaks, south-central Oregon, USA, 1996–1998. Treatments consisted of the removal of lodgepole pine snags only; live trees and ponderosa pine snags were not harvested. Our hierarchical model requires replicated count data from multiple sample units across several time periods, during which the population is closed, to estimate abundance as a function of logging treatment and management district while accounting for imperfect and variable detection probability. We fit the model to point counts from 12 control and 12 treatment plots with 3 surveys during each breeding season, 1996–1998. We found evidence for a large, but imprecise, effect of salvage logging in all 3 years for only 1 species, the gray flycatcher (Empidonax wrightii). The abundance of the remaining species either did not change or displayed weak positive responses to the treatment. Although 3 foraging guilds increased in total abundance, 2 guilds did not change and the response of 1 guild changed direction in different years. Our results suggest that, unlike most postfire salvage logging prescriptions, selective harvesting after beetle outbreaks may meet multiple management objectives, including the maintenance of avian population sizes comparable to those found in unharvested stands. Future research should consider different sampling programs for those species with large home ranges (e.g., woodpeckers) that may not be sampled adequately using commonly employed programs (e.g., point count stations). © 2012 The Wildlife Society.

Wind energy continues to be one of the fastest growing renewable energy sources under development, and while representing a clean energy source, it is not environmentally neutral. Large numbers of bats are being killed at utility-scale wind energy facilities worldwide, raising concern about cumulative impacts of wind energy development on bat populations. We discuss our current state of knowledge on patterns of bat fatalities at wind facilities, estimates of fatalities, mitigation efforts, and policy and conservation implications. Given the magnitude and extent of fatalities of bats worldwide, the conservation implications of understanding and mitigating bat fatalities at wind energy facilities are critically important and should be proactive and based on science rather than being reactive and arbitrary.

Wind-turbine operations are associated with bat mortality worldwide; minimizing these fatalities is critically important to both bat conservation and public acceptance of wind-energy development. We tested the effectiveness of raising wind-turbine cut-in speed – defined as the lowest wind speed at which turbines generate power to the utility system, thereby reducing turbine operation during periods of low wind speeds – to decrease bat mortality at the Casselman Wind Project in Somerset County, Pennsylvania, over a 2-year period. Observed bat mortality at fully operational turbines was, on average, 5.4 and 3.6 times greater than mortality associated with curtailed (ie non-operating) turbines in 2008 and 2009, respectively. Relatively small changes to wind-turbine operation resulted in nightly reductions in bat mortality, ranging from 44% to 93%, with marginal annual power loss (≤ 1% of total annual output). Our findings suggest that increasing turbine cut-in speeds at wind facilities in areas of conservati...

Snags are critical structural features for managing biological diversity in forests of the Pacific Northwest, USA. However, commercial forests in this region often contain reduced numbers of snags compared to unmanaged forests and managers require effective methods to augment snag numbers in harvest units. Therefore, we created snags by topping live trees with a mechanical harvester and studied foraging and nesting use by cavity-nesting birds of these snags in clearcuts in Douglas-fir ( Pseudotsuga mensezii ) forests along the west slope of the Cascade Mountain Range and east slope of the Coast Range in Oregon, USA. We used a completely randomized design to assign 6 different treatments (single or scattered distribution by 3 different densities) to 31 different harvest units. We created 1111 snags from February 1997 through April 1999 and monitored them from 2–5 years after harvest (1999–2002). Fraction of created snags with nest cavities in harvest units was generally low across all treatments and years of the study, although some individual stands demonstrated increased nesting use with snag age. While the highest fractions of snags with nest cavities were found in units with low density and scattered snags, the mean fraction of snags used for nesting did not differ among treatments. Treatment type, distribution of snags (i.e., scattered or clumped), and associated interactions did not influence fraction of snags used for foraging. However, fraction of created snags used for foraging in all harvest units increased with snag age. Fraction of snags used for foraging was greatest in the low density treatments. While this technique provides managers with a relatively economical option for creating snags, mechanical harvesters cannot be used to create tall, large snags upon which several cavity-dependent species rely and provides only a partial solution to a critical forest management issue.

Information about the immediate and potentially prolonged impacts of salvage logging is needed to develop prescriptions that maintain forest productivity, reduce the risk of catastrophic fires, and conserve biological communities. Most salvage logging studies have investigated post-fire salvage, often clearcutting, and impacts documented in these studies may be more severe than selective logging prescriptions applied to forests affected by beetle outbreaks. We evaluated the effects of selective salvage logging on avian nest survival in beetle-killed lodgepole pine ( Pinus contorta ) forests on the Fremont and Winema National Forests, south-central Oregon, USA, 1997–1999. Using logistic-exposure models, we found that nest survival for weak (period nest survival: 0.64; 95% CL: 0.50, 0.75) and strong (period nest survival: 0.71; 95% CL: 0.46, 0.87) cavity nesters was significantly higher than for ground nesters (period nest survival: 0.31; 95% CL: 0.18, 0.46), while nest survival for open cup nesting birds (period nest survival: 0.57; 95% CL: 0.47, 0.66) was intermediate. We did not find significant differences in nest survival for American robin ( Turdus migratorius ), chipping sparrow ( Spizella passerine ), dark-eyed junco ( Junco hyemalis ), dusky flycatcher ( Empidonax oberholseri ), mountain chickadee ( Poecile gambeli ), or yellow-rumped warbler ( Dendroica coronata ) (these six species comprised ∼80% of the sample). Our results suggest that, unlike post-fire salvage logging, selective harvesting prescriptions after beetle outbreaks may be suitable for meeting multiple management objectives, including generating a flow of commodities and maintaining avian nest survival rates.

Forest management activities influence habitat suitability for bats, and knowledge of the roosting ecology of bats is fundamental to developing strategies for conserving bats in managed forests. Information on use of roosts by multiple species of bats in a given area may provide insight into interspecific ecological patterns and could improve management prescriptions to provide habitat for bats through time across diverse ownerships and over multiple spatial scales. We investigated use of conifer snags as roosts by females of 3 species of forest-dwelling bats in Douglas-fir (Pseudotsuga menzesii) forests in the western Oregon Cascade Range. We radiotagged 29 female big brown bats (Eptesicus fuscus), 55 long-legged myotis (Myotis volans), and 27 long-eared myotis (Myotis evotis) and located 42, 105, and 24 snag roosts for the 3 species, respectively. All 3 species most frequently used Douglas-fir snags and in similar proportions to their availability. Big brown bats and long-legged myotis rarely roosted in stands

Wind power is one of the fastest growing sectors of the energy industry. Recent studies have reported large numbers of migratory tree-roosting bats being killed at utility-scale wind power facilities, especially in the eastern United States. We used thermal infrared (TIR) cameras to assess the flight behavior of bats at wind turbines because this technology makes it possible to observe the nocturnal behavior of bats and birds independently of supplemental light sources. We conducted this study at the Mountaineer Wind Energy Center in Tucker County, West Virginia, USA, where hundreds of migratory tree bats have been found injured or dead beneath wind turbines. We recorded nightly 9-hour sessions of TIR video of operating turbines from which we assessed altitude, direction, and types of flight maneuvers of bats, birds, and insects. We observed bats actively foraging near operating turbines, rather than simply passing through turbine sites. Our results indicate that bats 1) approached both rotating and nonrotating blades, 2) followed or were trapped in blade-tip vortices, 3) investigated the various parts of the turbine with repeated fly-bys, and 4) were struck directly by rotating blades. Blade rotational speed was a significant negative predictor of collisions with turbine blades, suggesting that bats may be at higher risk of fatality on nights with low wind speeds.

Wind has become one of the fastest growing sources of renewable energy worldwide, but widespread and often extensive fatalities of bats have increased concern regarding the impacts of wind energy development on bats and other wildlife. We synthesized available information on patterns of bat fatalities from a review of 21 postconstruction fatality studies conducted at 19 facilities in 5 United States regions and one Canadian province. Dominance of migratory, foliage- and tree-roosting lasiurine species (e.g., hoary bat [Lasiurus cinereus]) killed by turbines was consistent among studies. Bat fatalities, although highly variable and periodic, consistently peaked in late summer and fall, coinciding with migration of lasiurines and other species. A notable exception was documented fatalities of pregnant female Brazilian free-tailed bats (Tadarida brasiliensis) in May and June at a facility in Oklahoma, USA, and female silver-haired bats (Lasionycteris noctivagans) during spring in Tennessee, USA, and...

Our purpose is to provide researchers, consultants, decision-makers, and other stakeholders with guidance to methods and metrics for investigating nocturnally active birds and bats in relation to utility-scale wind-energy development. The primary objectives of such studies are to 1) assess potential impacts on resident and migratory species, 2) quantify fatality rates on resident and migratory populations, 3) determine the causes of bird and bat fatalities, and 4) develop, assess, and implement methods for reducing risks to bird and bat populations and their habitats. We describe methods and tools and their uses, discuss limitations, assumptions, and data interpretation, present case studies and examples, and offer suggestions for improving studies on nocturnally active birds and bats in relation to wind-energy development. We suggest best practices for research and monitoring studies using selected methods and metrics, but this is not intended as cookbook. We caution that each proposed and execu...

At a time of growing concern over the rising costs and long-term environmental impacts of the use of fossil fuels and nuclear energy, wind energy has become an increasingly important sector of the electrical power industry, largely because it has been promoted as being emission-free and is supported by government subsidies and tax credits. However, large numbers of bats are killed at utility-scale wind energy facilities, especially along forested ridgetops in the eastern United States. These fatalities raise important concerns about cumulative impacts of proposed wind energy development on bat populations. This paper summarizes evidence of bat fatalities at wind energy facilities in the US, makes projections of cumulative fatalities of bats in the Mid-Atlantic Highlands, identifies research needs, and proposes hypotheses to better inform researchers, developers, decision makers, and other stakeholders, and to help minimize adverse effects of wind energy development.

I assessed the ability of dog–handler teams to recover dead bats (Chiroptera) during fatality searches typically performed at wind energy facilities to determine fatality rates for birds and bats. I conducted this study at the Mountaineer and Meyersdale Wind Energy Centers in West Virginia and Pennsylvania, USA, respectively. Dogs found 71% of bats used during searcher-efficiency trials at Mountaineer and 81% of those at Meyersdale, compared to 42% and 14% for human searchers, respectively. Dogs and humans both found a high proportion of trial bats within 10 m of the turbine, usually on open ground (88% and 75%, respectively). During a 6-day fatality search trial at 5 turbines at Meyersdale, the dog–handler teams found 45 bat carcasses, of which only 42% (n = 19) were found during the same period by humans. In both trials humans found fewer carcasses as vegetation height and density increased, while dog–handler teams search efficiency remained high. Recommendations for evaluating the biases and e...

Large numbers of bats are killed by wind turbines worldwide and minimizing fatalities is critically important to bat conservation and acceptance of wind energy development. We implemented a 2-year study testing the effectiveness of an ultrasonic acoustic deterrent for reducing bat fatalities at a wind energy facility in Pennsylvania. We randomly selected control and treatment turbines that were searched daily in summer and fall 2009 and 2010. Estimates of fatality, corrected for field biases, were compared between treatment and control turbines. In 2009, we estimated 21-51% fewer bats were killed per treatment turbine than per control turbine. In 2010, we determined an approximate 9% inherent difference between treatment and control turbines and when factored into our analysis, variation increased and between 2% more and 64% fewer bats were killed per treatment turbine relative to control turbines. We estimated twice as many hoary bats were killed per control turbine than treatment turbine, and nearly twice as many silver-haired bats in 2009. In 2010, although we estimated nearly twice as many hoary bats and nearly 4 times as many silver-haired bats killed per control turbine than at treatment turbines during the treatment period, these only represented an approximate 20% increase in fatality relative to the pre-treatment period for these species when accounting for inherent differences between turbine sets. Our findings suggest broadband ultrasound broadcasts may reduce bat fatalities by discouraging bats from approaching sound sources. However, effectiveness of ultrasonic deterrents is limited by distance and area ultrasound can be broadcast, in part due to rapid attenuation in humid conditions. We caution that an operational deterrent device is not yet available and further modifications and experimentation are needed. Future efforts must also evaluate cost-effectiveness of deterrents in relation to curtailment strategies to allow a cost-benefit analysis for mitigating bat fatalities.

At a time of growing concern over the rising costs and long-term environmental impacts from the use of fossil fuels, wind energy has become an increasingly important sector of the electrical power industry. However, large numbers of bats are being killed at utility-scale wind energy facilities, and these fatalities raise important concerns about cumulative impacts of proposed wind energy development on bat populations. We discuss our current state of knowledge on patterns of bat fatalities at wind facilities, present new information on cumulative fatalities in the USA and Canada, and present findings from mitigation studies. Given the magnitude and extent of fatalities of bats worldwide, the conservation implications of understanding and mitigating bat fatalities at wind energy facilities are critically important.

Sex- and age-specific fecal lungworm (Protostrongylus spp.) larvae concentrations in Rocky Mountain bighorn sheep (Ovis canadensis canadensis) from the Cinnabar Winter Range in southwestern Montana were determined. All 228 fecal samples collected from bighorn sheep of known sex and age class from November to April, 1984 to 1987 contained first-stage lungworm larvae. Fecal lungworm concentrations of ewes and rams declined significantly from late fall through early spring, whereas number of lungworms in lamb feces increased as winter progressed.

Roosts are a critical habitat component for bats and may influence their survival and fitness. We used radiotelemetry to investigate characteristics of day-roosts of female long-eared myotis (Myotis evotis) in watersheds characterized by different forest conditions and the spatial relationships between day-roosts and available water. We tracked 21 bats to 73 roosts (n = 102 occasions) from June to August 1996 and 1997 on the western slope of the Cascade Mountains, Oregon. Bats primarily used conifer stumps as day-roosts in watersheds dominated by younger forests and used conifer snags, and to a lesser extent conifer stumps, in watersheds with greater proportions of older forests. Individual long-eared myotis used different types of structures as day-roosts, and type of structure used did not differ with reproductive condition. Day-roosts were primarily located in upslope habitat and averaged 0.59 ± 0.03 km from available water and 0.66 ± 0.02 km from capture sites. Roosts were not located closer to available water than random points, but were closer than random points to captures sites. Conifer snags used as day-roosts averaged 34 ± 5 m in height and 93 ± 12 cm diameter at breast height (dbh); snags in intermediate stages of decay had highest use. Use of conifer snags was positively associated with the number of snags within 20 m and negatively associated with distance from stand edge. Conifer stumps used as day-roosts averaged 133 ± 9 cm in height and 59 ± 4 cm dbh. Western hemlock and Douglas-fir stumps were used more often than western redcedar stumps as day-roosts. Odds of a stump being used as a day-roost increased with increasing height of the stump (downhill side) and whether it was situated in a gap in vegetation. We contend that management of day-roosts for forest-dwelling bats should focus on maintaining large conifer snags across landscapes through space and time. In landscapes where there are relatively few large conifer snags, stumps appear to provide important, but ephemeral, roosts for long-eared myotis.

Fecal indicators of nutritional status of wild ungulates are less constrained than blood or urine analyses. Thus, we assessed the potential for fecal nitrogen concentration to predict winter dietary quality for Rocky Mountain bighorn sheep (Ovis canadensis) in Wyoming. Dietary nitrogen concentration and percent in vitro dry matter digestibility increased linearly with increases in fecal nitrogen concentration for hand-plucked diets of wild sheep on 4 winter ranges and for tannin-free diets fed to 3 penned adult female bighorn sheep (2 were 1/8 mouflon [O. orientalis]). A linear'regression developed from field samples gathered in 2 winters accurately predicted winter dietary nitrogen concentrations using fecal nitrogen levels from other winters