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Studies examining how wildlife populations perceive and respond to habitat are common, and many attempt to understand how the quality of available habitats influences population processes such as survival and recruitment. Traditional methods to estimate habitat quality (e.g. population density) have not led to great advancement in our understanding of relationships between habitat and fitness in recent years. Metrics from the discipline of conservation physiology could help researchers to address these difficulties and to meet the challenges that habitat alteration poses to biodiversity. Incorporating physiological metrics that relate energetics or environmental stress to habitats may be powerful measures of habitat quality. By quantifying field metabolic rates, body condition, or concentrations of stress hormones in individual organisms, researchers may identify mechanisms associated with habitat that underlie observed patterns in vital rates (survival and fecundity). Physiological metrics offer useful tools that may identify mechanisms of habitat quality and detect the causes of declines in biodiversity. However, integration among physiologists, ecologists and conservation biologists will require new partnerships and approaches to respond to complex ecological issues.

Environmental temperatures affect nearly all aspects of ectotherm physiology, including terrestrial salamanders. Therefore, habitat disturbances that alter temperature regimes may interact with physiological processes to affect energy budgets of salamanders or constrain surface activity and possibly lead to changes in population-level parameters. We hypothesized that warmer surface temperatures following harvesting of canopy trees could cause surface-active salamanders to expend more energy for metabolism, potentially leaving a smaller proportion of the energy budget available for reproduction or storage. From 2006 to 2008, we quantified temperature regimes of salamander refugia in a field experiment replicated at 4 sites that included plots subjected to a timber harvest and plots not manipulated during this time period. At each site, we quantified temperature regimes in regenerating forest stands which, approximately 10 years earlier, experienced a range of harvest intensity from shelterwood to silvicultural clearcut. Further, we compared energetic parameters including 1) calories required to maintain homeostasis across an active season, 2) abundance of available potential energy (i.e., invertebrate prey), and 3) a measure of growth and storage (i.e., body condition index) among silvicultural treatments for surface-active salamanders. For surface-active eastern red-backed salamanders (Plethodon cinereus), mean calories required for maintenance were approximately 33% greater in recently harvested forest compared to unharvested controls, but body condition was inconsistent among treatments, and invertebrate abundances were similar among treatments but differed by study site. In contrast, we did not detect a treatment effect in any energetic metric 8-14 growing seasons after harvesting. Given that surface-active salamanders in recently harvested forest may be forced to restrain behaviors associated with foraging and mating or trade-off growth or reproduction for increased basic maintenance costs, energetics may be an important but overlooked short-term contributor to observed changes in abundances, reproductive demography, or surface activities after timber harvesting. Managing for both the rapid recovery of understory vegetation and retention of large stumps and logs may help mitigate warming of microclimate for salamanders and should be considered further. ß 2011 The Wildlife Society.

Snowshoe hares (Lepus americanus) are an important prey species and a dominant herbivore across much of their North American range, and researchers have questioned the influences of forestry practices that alter habitat for hares and the potential community‐level effects on carnivores. We examined the effects of precommercial thinning (PCT) from 1 to 11 years posttreatment on snowshoe hares. In the commercial forests of northern Maine, USA, we counted and cleared hare pellets twice a year during 2001 and 2002 on >46 km of pellet transects across 30 regenerating conifer stands (17 treated with PCT) previously treated with an aerial application of herbicide. We compared densities of snowshoe hare pellets among 3 development classes with (1 yr after thinning, 6 yr after thinning, and 11 yr after thinning) and without thinning (stands with a similar history of clearcut and herbicide treatment but no thinning). During both years, densities of hares were lower in stands treated with PCT than in similar unthinned stands across the 3 development classes and during both leaf‐off and leaf‐on seasons (P < 0.001). Within both thinned and unthinned stands, hare density was greatest in stands in the 1‐year development class when compared to the 6‐year and 11‐year development classes, but a statistical difference (P = 0.048) among classes was evident only during leaf‐off seasons. Precommercial thinning was associated with densities of snowshoe hares that were approximately half of those in similar unthinned stands up to at least 11 years posttreatment; however, thinned stands may retain densities of hares greater than stands managed using other forest harvesting regimes. Our results apply to core portions of stands with crop trees spaced at 1.8–2.4‐m intervals following complete overstory removal and herbicide treatment. We advocate caution when applying our results to other thinning regimes or across broader spatial scales.

Population densities are costly and logistically infeasible to measure directly across the broad geographic ranges of many wildlife species. For snowshoe hares (Lepus americanus), a keystone species in northern boreal forest, indirect approaches for estimating population densities based on fecal pellet densities have been developed for boreal forest in northwestern Canada and in conifer-dominated montane forest in Idaho. Previous authors cautioned against applying these estimates across the geographic range of hares without further testing, but no published relationships for estimating densities from pellet counts are available for the mixed conifer-deciduous forests of the southeastern portion of the hare's range in North America. Thus, we estimated pellet and hare densities in 12 forested stands, 4 sampled twice during 1981-1983 and 8 sampled once during 2000-2002. Mark-recapture estimated densities of snowshoe hares from eastern and western Maine during 1981Maine during -1983 were linearly related to pellet densities to 15,000 pellets/ha/month (1.5 hares/ha) (Adj. r 2 ¼ 0.87, n ¼ 8, P , 0.001) and accurately predicted densities of hares ( x ¼ 7 % greater) estimates than actually observed at higher pellet densities sampled in northern Maine

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Forests are potential sources for a wide range of alternative fuels, which could reduce dependency on fossil fuels and carbon emissions, but sustainability of producing biofuels from forests has not been well‐studied. Therefore, we investigated effects of woody biomass harvest, intercropping perennial grasses, and combinations of these treatments on herpetofauna in loblolly pine (Pinus taeda) plantations in a randomized and replicated field experiment in eastern North Carolina, USA. We sampled amphibians and small reptiles with drift fence arrays from April to July during 1 and 2 years after treatment establishment. We had 425 captures of 15 species of herpetofauna across the 2 sampling seasons, but did not observe large general effects of biomass removal or planting of switchgrass (Panicum virgatum) in pine plantations on detection, diversity, or relative abundance. However, planned contrasts indicated Simpson's index of diversity was greater in plots managed for switchgrass only compared with pine plantations during year 2, and that captures of southern toads (Anaxyrus terrestris) were less common in switchgrass plots than in pine plantations intercropped with switchgrass. Neither intercropping switchgrass with pine nor removal of harvest residuals caused herpetofauna diversity or abundance of common species to differ from traditional plantation management during the first 2 years following treatment establishment. With the exception of switchgrass‐only plots, which had lower herpetofauna species evenness, the potential practices we considered for biofuels production are unlikely to have short‐term effects on herpetofauna relative to traditional pine management. Future research should monitor herpetofauna through succession and consider landscape‐scale effects and other potential feedstock sources. © 2013 The Wildlife Society.