Artificial night lighting (or ecological light pollution) is only now gaining attention as a source of long-term effects on the ecology of both diurnal and nocturnal animals. The limited data available clearly indicate that artificial light can affect physiology and behaviour of animals, leading to ecological consequences at the population, community, and ecosystem levels. Aquatic ecosystems may be particularly vulnerable to such effects, and nocturnally breeding animals such as frogs may be especially affected. To address this potential, we quantify the effects of artificial light on calling and movement behaviour in a rural population of male green frogs ( Rana clamitans melanota (Rafinesque, 1820)) during the breeding season. When exposed to artificial light, frogs produced fewer advertisement calls and moved more frequently than under ambient light conditions. Results clearly demonstrate that male green frog behaviour is affected by the presence of artificial light in a manner that has the potential to reduce recruitment rates and thus affect population dynamics.

Road mortality is a widely recognized but rarely quantified threat to the viability of amphibian populations. The global extent of the problem is substantial and factors affecting the number of animals killed on highways include life-history traits and landscape features. Secondary effects include genetic isolation due to roads acting as barriers to migration. Long-term effects of roads on population dynamics are often severe and mitigation methods include volunteer rescues and under-road tunnels. Despite the development of methods that reduce road kill in specific locations, especially under-road tunnels and culverts, there is scant evidence that such measures will protect populations over the long term. There also seems little likelihood that funding will be forthcoming to ameliorate the problem at the scale necessary to prevent further population declines.© 2013 Society for Conservation Biology.

Numerous factors are contributing to the loss of biodiversity. These include complex effects of multiple abiotic and biotic stressors that may drive population losses. These losses are especially illustrated by amphibians, whose populations are declining worldwide. The causes of amphibian population declines are multifaceted and context-dependent. One major factor affecting amphibian populations is emerging infectious disease. Several pathogens and their associated diseases are especially significant contributors to amphibian population declines. These include the fungi Batrachochytrium dendrobatidis and B. salamandrivorans, and ranaviruses. In this review, we assess the effects of these three pathogens on amphibian hosts as found through experimental studies. Such studies offer valuable insights to the causal factors underpinning broad patterns reported through observational studies. We summarize key findings from experimental studies in the laboratory, in mesocosms, and from the field. We also summarize experiments that explore the interactive effects of these pathogens with other contributors of amphibian population declines. Though well-designed experimental studies are critical for understanding the impacts of disease, inconsistencies in experimental methodologies limit our ability to form comparisons and conclusions. Studies of the three pathogens we focus on show that host susceptibility varies with such factors as species, host age, life history stage, population and biotic (e.g., presence of competitors, predators) and abiotic conditions (e.g., temperature, presence of contaminants), as well as the strain and dose of the pathogen, to which hosts are exposed. Our findings suggest the importance of implementing standard protocols and reporting for experimental studies of amphibian disease.

Although possessing novel replicative and structural features, the family Iridoviridae has not been as extensively studied as other families of large, DNA-containing viruses (e.g., poxviridae and herpesviridae). This oversight most likely reflects the inability of iridoviruses to infect mammals and birds, and their heretofore low pathogenicity among cold-blooded animals and invertebrates. In fact, the original frog virus isolates (e.g., frog viruses 1-3) would likely have been considered orphan viruses since they were isolated from apparently healthy frogs. However, recent disease outbreaks among commercially and recreationally important fish, cultured and wild frogs, and endangered salamanders has challenged this benign view and have implicated several members of the genus Ranavirus as pathogens. This review explores three facets of ranavirus biology. In the first the salient features of ranavirus replication are summarized using frog virus 3 as a model. Secondly, criteria for characterizing new ranavirus isolates, based on biochemical (viral protein profiles, DNA restriction fragment length polymorphisms, and nucleotide sequence analysis), ecological (host range, tissue tropism), and clinical considerations, are detailed. Lastly, the principal agents of ranavirus-mediated disease and immune responses to these viruses are discussed. In light of the above, it is clear that ranaviruses are no longer orphan viruses, and that they have a significant impact on diverse populations of ectothermic animals.

Mortality from road-kills may figure among the important causes of decline in amphibian populations and species extinctions worldwide. Evaluation of the magnitude, composition, and temporal and spatial distributions of amphibian road-kills is a key step for mitigation planning, especially in peri-urban reserves. Once a month for 16 months, we surveyed, on foot, a 4.4 km section of state road ERS-389 bordering the Itapeva reserve in the southern Atlantic Forest. We recorded 1433 anuran road-kills and estimated a mortality rate of 9002 road-kills/km/year. The species most often recorded were the largest ones: Leptodactylus latrans, Rhinella icterica, Leptodactylus gracilis and Hypsiboas faber; 54.5% of the carcasses could not be identified. Anuran mortality was concentrated in summer, and was associated with temperature, rainfall and photoperiod. Leptodactylus road-kills were strongly influenced by vehicle traffic, probably because of its high abundance during the entire study period. Road-kill hotspots differed for anurans as a group and for single species, and we found an association among spatial patterns of mortality and types of land cover, distance from the nearest waterbody, roadside ditches, and artificial light. Traffic should be banned temporarily during periods of high mortality, which can be forecasted based on meteorological data. A comprehensive mitigation approach should take into account hotspots of all anuran records, and also of target species for selecting locations for amphibian passages and fencing. Roadside ditches, artificial waterbodies, and conventional street lights should be reduced as much as possible, since they may represent ecological traps for anuran populations.Copyright © 2012 Elsevier Ltd. All rights reserved.

Habituation is a term commonly used to explain a decrement in response intensity to a repeated stimulus or set of stimuli. In the stress literature, hormonal habituation is often used to describe a situation where an individual has learned to perceive a repeated stressor as innocuous, and thus the intensity of the release of hormonal stress mediators reduces over time. Consequently, a habituated individual is not considered stressed. There are, however, situations where an individual may be chronically stressed despite a reduction in the response intensity of hormonal stress mediators to a repeated stimulus. These alternative explanations are rarely considered in field studies even though a false conclusion that an individual has habituated (i.e., is not stressed) may lead to false conclusions regarding the animal's overall physiology and health. The present paper provides four alternative explanations for an observed attenuation in the response of hormonal stress mediators to a repeated stimulus or set of stimuli which lead to six criteria that define habituation in a field context. Furthermore, we propose four diagnostic tests to help distinguish hormonal habituation from these alternative explanations in field studies. These tests will help identify hormonal habituation in free-living animals and prevent potential problems of falsely describing an individual or population of individuals as habituated.

Global warming, light pollution and noise are common human-induced environmental problems that are escalating at a high rate. Their consequences on wildlife have mostly been overlooked, with the exception of a few species with respect to climate change. The problems often occur simultaneously and exert their negative effects together at the same time. In other words, their impacts are combined. Studies have never focused on more than one problem, and so, such combined effects have never been understood properly. The review addresses this lacuna in the case of amphibians, which are a highly vulnerable group. It divides the overall impacts of the problems into seven categories (behaviour, health, movement, distribution, phenology, development and reproductive success) and then assesses their combined impact through statistical analyses. It revealed that amphibian calling is the most vulnerable aspect to the combined impacts. This could provide important input for conservation of amphibians.

Research is necessary to identify patterns in nature, to understand how a system functions, and to make predictions about the future state of an ecosystem. Applied research in conservation biology can identify effective strategies to maintain biodiversity, though many papers end with the conclusion that more research is needed. However, more research does not necessarily lead to solutions. We use the ongoing global decline of amphibians as a salient example to highlight limitations in current conservation research, and to focus on finding solutions which are directly relevant for conservation. While research has been conducted since declines were first detected in the 1990s, outside a few specific examples, little progress in conservation has been achieved. We suggest that the case of amphibian declines is relevant to conservation science in general, as the current paradigm for conservation is that management is planned after research is completed; research and management are not effectively (and not directly) connected. This disconnect illustrates the knowledge-action divide which has been identified as a serious deficiency in conservation. Accordingly, we use this introductory paper to the Special Issue (Amphibian conservation in the Anthropocene: Progress and challenges) to describe amphibians as a conservation dilemma, and to make the case for a different, more pragmatic, and more solutions-focused view of conservation research.

When conserving or protecting rare or endangered species, current general guidelines for reducing light pollution might not suffice to ensure long-term threatened species’ survival. Many protected areas are exposed to artificial light at levels with the potential to induce ecological impacts with unknown implications for the ecosystems they are designated to protect. Consequently, it is recommended that precautionary methods for the avoidance and mitigation of light pollution in protected areas be integrated into their management plans. This paper’s aims are to present an overview of best practices in precautionary methods to avoid and mitigate light pollution in protected areas and to identify and discuss what ecosystems should be considered light-sensitive and how to prioritise species and habitats that need protection from artificial light, including examples of legislation covering ecological light pollution in the European Union and in Sweden. The important aspects to include when considering light pollution at a landscape level are listed, and a proposal for prioritisation among species and habitats is suggested. Sensitive and conservation areas and important habitats for particularly vulnerable species could be prioritised for measures to minimise artificial lighting’s negative effects on biodiversity. This may be done by classifying protected natural environments into different zones and applying more constrained principles to limit lighting. The light pollution sensitivity of various environments and ecosystems suggests that different mitigation strategies and adaptations should be used depending on landscape characteristics, species sensitivity and other factors that may determine whether artificial light may be detrimental. Issues of the currently used measurement methods for artificial light at night are reviewed. We also propose and discuss the principles and benefits of using standardized measurement methods and appropriate instrumentation for field measurements of artificial light concerning the environmental impact of light pollution.

In order to clarify the threat status of Chinese amphibians and the conditions threatening these species, we compiled a red list of amphibians in China based on the IUCN Red List Categories and Criteria (Version 3.1), and Guidelines for Application of IUCN Red List Criteria at Regional and National Levels (Version 4.0). This red list, which includes details on population and habitat status, rates of population decline, and projected population trends, will facilitate development of protective management agreements for Chinese administrative departments, the Chinese public, and international organizations. We evaluated 408 amphibian species and discovered that 43.1% of the evaluated species, i.e., 176 species, were threatened, which exceeds the net percentage of threatened amphibian species throughout the entire world. One species was classified as “Extinct” and another species was classified as “Regionally Extinct”. There are 272 amphibian species endemic to China, and 48.9% of them were threatened. The tailed amphibian order (Urodela) possessed the highest ratios of threatened species, followed by the tailless amphibian order (Anura). The families with the highest percentages of threatened species were Cryptobranchidae (100% threatened), Hynobiidae (86.7% threatened), and Dicroglossidae (78.1% threatened). In eleven provinces, more than 30% of the local amphibian species were classified as threatened species, with the provinces Sichuan (40.8%), Guangxi (39.2%), and Yunnan (37.0%) having the highest percentage of threatened amphibians. Most of China’s amphibians are distributed in southwestern and southern China and below 2,000 m altitude. Habitat degeneration and loss, human capture, and pollution were the three leading threats to amphibians in China. In order to restore endangered amphibian populations and conserve amphibian diversity in China, more population surveys and monitoring projects as well as scientific research on Chinese amphibians are necessary.

为了了解我国两栖动物受威胁现状和致危因素, 进而制定相关的保护措施和开展国际合作, 本文依据中国两栖动物野生种群与生境现状, 利用《IUCN物种红色名录濒危等级和标准》(3.1版)和《IUCN物种红色名录标准在国家或地区的应用指南》(4.0版), 对中国已知的408种两栖动物的濒危状况进行了评估, 并编制了《中国两栖动物红色名录》。评估结果表明: 中国两栖动物有1种灭绝, 1种区域灭绝, 受威胁的两栖动物共计176种, 占评估物种总数的43.1%, 明显高于《IUCN濒危物种红色名录》(2015)的物种受威胁率(30.8%)。中国两栖动物特有种272种, 其中48.9%属于受威胁物种。中国两栖动物受威胁比例最高的目是有尾目(63.4%), 明显高于无尾目(39.0%); 受威胁比例最高的科是隐鳃鲵科(Cryptobranchidae) (仅有1种, 100%受威胁), 小鲵科(Hynobiidae) (86.7%)和叉舌蛙科(Dicroglossidae) (78.1%)。有11个省区的受威胁物种数占本省区两栖动物物种总数的30%及以上, 前3位分别是四川(40.8%)、广西(39.2%)和云南(37%)。中国大多数两栖动物物种分布在西南山地和华南地区, 以海拔2,000 m以下区域为主。栖息地退化或丧失、捕捉、环境污染列受威胁两栖动物致危因子的前3位。鉴于中国两栖动物区系的复杂性和独特性, 进一步加强两栖动物资源调查、种群和生境监测及相关科学研究, 仍是今后一段时期开展两栖动物多样性保护和濒危物种拯救行动的关键性基础工作。

Many organisms depend on acoustic communication for myriad functions, and have evolved behaviours to minimize effects of naturally occurring acoustic interference. However, as habitats are subject to increased alteration, anthropogenic noise becomes unavoidable, and how animals overcome such interference is not well understood. In most ecosystems, only a subset of frog species is associated with disturbed habitats; the ability of these species to overcome exogenous noise suggests that habitat associations may be related to species' response to noise. We tested the hypothesis that frogs associated with largely undisturbed forest habitat would be less likely to increase call output in response to exogenous noise than would those associated with disturbed or open habitat. While this relationship was not significant, we found a slight trend supporting the hypothesis. We then asked whether anthropogenic noise affects chorus tenure at individual- or at chorus-levels. Male frogs exposed to anthropogenic noise decreased both the number of days present at the chorus and the nightly chorus duration relative to controls. Because females generally join choruses late at night to breed, the effects of noise shown here are likely to substantially decrease frog reproductive success; thus, the acoustic environment may play an important role in shaping population dynamics and in amphibian declines.

<p id="p00015"><strong>Background &#x00026; Aim:</strong> Nesting behavior is important for birds because this stage is critical for breeding success. Since urbanization is expanding worldwide, birds living in cities face huge challenges but the urban environment can also provide living opportunities. This review summarizes bird nesting behaviors in cities, analyzing the influence of factors such as climate, food resources, nest site availability, predation pressure, pollution, and anthropogenic disturbance on bird nesting based on publications in Biblioshiny programme. <br><strong>Summary: </strong>This study demonstrates that urbanization influences bird nesting period, nest site and nest material selection significantly, and that spatio-temporal nesting ranges and nesting materials differ between urban and rural birds. We highlight the need to evaluate whether city birds are well adapted or negatively affected by urbanization, which would require specific analysis of target populations and habitat conditions. <br><strong> Perspectives: </strong>We should propose effective and specific suggestions to protect city birds during urbanization based on our research results, instead of simply providing general guidelines. Developing citizen science to solve practical issues in urban animal ecology is a promising direction for the future.</p>

繁殖期筑巢是鸟类生活史的重要阶段, 是鸟类繁殖成功的关键保障。全球范围的城市化加速推进, 使城市中筑巢繁殖的鸟类面临挑战的同时又为其提供了特殊机遇。本文通过搜索现有文献, 利用Biblioshiny程序提取并整合关键词, 得到城市鸟类生态研究的热点领域, 分析了城市气候、食物资源、巢址资源、捕食压力、污染和人为干扰对鸟类筑巢的影响, 并对今后城市化对鸟类筑巢影响研究中亟需解决的问题进行了展望。城市化对鸟类筑巢期、巢址选择及巢材选择产生显著影响, 与栖息在村镇生境的鸟类相比, 在城市中繁殖的鸟类在筑巢时间、空间和巢材使用上出现变化。在城市中筑巢的鸟类到底是通过调整行为策略作出积极适应, 还是被动接受城市环境中的诸多负面干扰, 需要针对研究对象和特定的城市栖息生境进行及时评估, 而非泛泛之谈。要在研究结论基础上, 深入思考并提出城市化建设过程中有利于鸟类种群和群落保护的具体措施, 高效发挥公民科学作用以解决城市中的鸟类保护实践问题。

Amphibians and reptiles are important indicator species of ecosystem health, and they are sensitive to environmental changes and are often regarded as critical “early warning systems”. Many of their populations are undergoing rapid decline and therefore a long-term monitoring system is imperative to identify immediate threats to the animals. Monitoring program on Chinese amphibians began in the Zoige wetlands in 1997. Since 2000, a great number of monitoring studies of amphibians and reptiles have been carried out in mountains of Southwest China, Taiwan, and other regions with rich biodiversity. In 2011, the Ministry of Environmental Protection officially launched the “Amphibian Observation Initiative of China” program, which expanded regional programs to country-wide using both qualitative and quantitative methods to collect amphibian biodiversity data across long-term temporal scales. From an ecosystem viewpoint, long-term monitoring studies should include not only species distribution, richness, and population structure, but also population growth, key life-history traits, species interactions (e.g., predation, competition, and mutualism), community structure, and other dynamic factors. The program “Monitoring and Research of Amphibians and Reptiles in Key Areas of China” will cover 22 key areas with rich biodiversity and high habitat heterogeneity across China. As part of the Chinese Biodiversity Monitoring and Research Network (Sino BON), this program aims to combine intensive field surveys and ecological modeling techniques to evaluate population dynamics and community structures of amphibian and reptile species in the study areas.

两栖爬行动物是良好的环境指示物种, 是环境变化的早期预警系统之一, 目前正经历着全球范围的种群快速下降和物种灭绝。为了观测和研究物种及种群下降或灭绝的态势和机制, 亟需对我国两栖爬行动物多样性开展长期监测和研究。在中国, 对两栖爬行动物的监测研究始于1997年对若尔盖湿地两栖动物的监测。此后, 两栖爬行动物监测率先在西南山地、台湾等生物多样性丰富地区开展起来。2011年, 在借鉴美国和英国的两栖爬行动物监测计划的基础上, 环境保护部启动了&#x0201c;两栖类示范观测项目&#x0201d;, 初步实现了由点到面、由定性到定量、由静态向动态的突破。因为单一类群的监测仅代表生态系统的基本组成, 而从生态系统角度考量, 必须深入研究生态系统的结构(食物网中各类群的捕食、竞争、共生等种间关系)和动态(各类群的生长、繁殖、种群波动和致危因素等)。因此, 作为中国生物多样性监测与研究网络(Sino BON)的重要组成部分, &#x0201c;中国关键地区两栖爬行动物监测与研究专项网&#x0201d;项目将在22个生物多样性关键地区对典型生态系统中的两栖爬行动物组成、种群动态和结构进行长期监测与研究, 构建生态模型, 探讨两栖爬行动物的种群现状、群落结构及其动态趋势和相关机制, 制定和不断完善我国两栖爬行动物应对未来环境变化的保护和管理对策。

<p id="p00005"><strong>Background &#x00026; Aim:</strong> Habitat loss and fragmentation, driven by expansion of global transport infrastructure networks, has become one of the significant factors contributing to the decline of biodiversity. Many studies on the impact of roads on wildlife have been conducted abroad, yet only a modest number of studies have been conducted in China.</p> <p id="p00010"><strong>Summary: </strong>This review summarizes 144 case studies conducted in China by the year 2021 and 210 posts relating to roadkill from Sina Microblog. The impacts of roads on wildlife in China were divided into seven types: habitat loss, habitat fragmentation, avoid or gather at the roadside, hinder or promote migration, population isolation, wildlife crossing structures and roadkill. Recent, relevant studies in China are mainly concentrated in Hoh Xil, Changbai Mountains, and Qinling Mountains. The main species studied are ungulates on Tibetan Plateau, the giant panda (<i>Ailuropoda melanoleuca</i>) and Asian elephant (<i>Elephas maximus</i>).</p> <p id="p00015"><strong>Perspectives: </strong>Collecting data on the impacts of roads on wildlife, is critical to inform interdisciplinary and multi-departmental management and conservation solutions of road-wildlife conflicts in China. Social media platforms can be important sources of data on roadkill occurrences.</p>

全球交通基础设施网络的不断扩张导致的栖息地丧失和破碎化已成为生物多样性下降的主要影响因素之一。国外开展了大量的道路对野生动物生存影响的研究, 相对而言, 我国在该领域的研究刚刚起步。本文通过总结截止于2021年国内的144篇案例研究文献以及新浪微博中210条道路交通伤害信息, 将我国道路对野生动物的影响分为栖息地丧失、栖息地破碎化、回避或聚集路边、阻碍或促进迁移、种群隔离、野生动物通道和道路交通伤害等方面, 从研究方法、研究地点、研究物种和研究结果等不同角度进行梳理和总结。近年来, 我国的相关研究呈现不断增长的趋势, 研究地点主要集中在可可西里、长白山和秦岭地区; 研究物种主要为青藏高原有蹄类、大熊猫(Ailuropoda melanoleuca)和亚洲象(Elephas maximus)。未来重点发展方向应包括: (1)道路野生动物基础数据采集平台建设; (2)我国不同动物地理分区的道路野生动物相关研究; (3)深入开展学科交叉与部门合作以及国际交流合作。公众在社交媒体发布的相关信息表明近年来公众对道路交通伤害问题越来越关注, 未来开展基于公民科学收集道路交通伤害数据具有迫切性和可行性。

Changing light conditions due to human activities represents an important emerging environmental concern. Although changes to natural light conditions can be independently detrimental, in nature, organisms commonly face multiple stressors. To understand the consequences of altered light conditions, we exposed a model amphibian (wood frog; Lithobates sylvaticus) to a control and two anthropogenic light conditions: intensified daytime illuminance and artificial light at night - ALAN (intensified daytime illuminance + extended photoperiod). We measured (1) metrics of fitness (hatching success as well as survival to, size at, and time to metamorphosis) (2) susceptibility (time to death) to a commonly co-occurring anthropogenic stressor, road salt (NaCl) and (3) susceptibility (infection load) to a common parasite (trematode). We also explored behavioral (swimming activity) and physiological (baseline corticosterone (CORT) release rates) changes induced by these light conditions, which may mediate changes in the other measured parameters. We found that both intensified daytime illuminance and ALAN reduced hatching success. In contrast, for amphibians that successfully hatched, neither treatment affected amphibian survival or time to metamorphosis but individuals exposed to ALAN were larger at metamorphosis. The light treatments also had marginal effects; individuals in ALAN treatments were more susceptible to NaCl and trematodes. Finally, tadpoles exposed to ALAN moved significantly less than tadpoles in the control and intensified daytime illuminance treatments, while light had no effect on CORT release rate. Overall, changes in light conditions, in particular ALAN, significantly impacted an amphibian model in laboratory conditions. This work underscores the importance of considering not only the direct effects of light on fitness metrics but also the indirect effects of light with other abiotic and biotic stressors. Anthropogenic-induced changes to light conditions are expected to continue increasing over time so understanding the diverse consequences of shifting light conditions will be paramount to protecting wildlife populations.Copyright © 2019 Elsevier Ltd. All rights reserved.

Loss of acoustic habitat due to anthropogenic noise is a key environmental stressor for vocal amphibian species, a taxonomic group that is experiencing global population declines. The Pacific chorus frog () is the most common vocal species of the Pacific Northwest and can occupy human-dominated habitat types, including agricultural and urban wetlands. This species is exposed to anthropogenic noise, which can interfere with vocalizations during the breeding season. We hypothesized that Pacific chorus frogs would alter the spatial and temporal structure of their breeding vocalizations in response to road noise, a widespread anthropogenic stressor. We compared Pacific chorus frog call structure and ambient road noise levels along a gradient of road noise exposures in the Willamette Valley, Oregon, USA. We used both passive acoustic monitoring and directional recordings to determine source level (i.e., amplitude or volume), dominant frequency (i.e., pitch), call duration, and call rate of individual frogs and to quantify ambient road noise levels. Pacific chorus frogs were unable to change their vocalizations to compensate for road noise. A model of the active space and time ("spatiotemporal communication") over which a Pacific chorus frog vocalization could be heard revealed that in high-noise habitats, spatiotemporal communication was drastically reduced for an individual. This may have implications for the reproductive success of this species, which relies on specific call repertoires to portray relative fitness and attract mates. Using the acoustic call parameters defined by this study (frequency, source level, call rate, and call duration), we developed a simplified model of acoustic communication space-time for this species. This model can be used in combination with models that determine the insertion loss for various acoustic barriers to define the impact of anthropogenic noise on the radius of communication in threatened species. Additionally, this model can be applied to other vocal taxonomic groups provided the necessary acoustic parameters are determined, including the frequency parameters and perception thresholds. Reduction in acoustic habitat by anthropogenic noise may emerge as a compounding environmental stressor for an already sensitive taxonomic group.

Road networks are central drivers of biodiversity loss and their impacts are rapidly expanding. Pond-breeding amphibians are highly vulnerable to road impacts because they typically travel from terrestrial to aquatic habitats to breed and leave the aquatic habitat for the terrestrial as newly emerged juveniles. If amphibians must cross roads during migrations, mass mortalities and local extirpation can result. While mortality at any life stage is concerning, juveniles should be of special interest when assessing road mortality and mitigation (e.g., tunnels to facilitate safe seasonal migrations) because their fate can have a disproportionate impact on population dynamics. We highlight a pervasive lack of information about juveniles which contributes to an inability to demonstrate the effect of road mitigation actions at the population level. This limits our capacity to implement conservation strategies and improve outcomes for vulnerable amphibian populations. We examine this knowledge gap using published mathematical models of amphibian populations and studies on efforts to mitigate road impacts. We further discuss the successful use of volunteers (i.e., citizen science) and identify how these efforts might be more broadly applied to address the dearth of data on juveniles and to mitigate the levels of mortality caused by roads. There are discrepancies between theoretical population models and conservation practice and we evaluate the potential causes and implications for the effectiveness of conservation projects in improving population persistence. Road mortality is a common and increasingly important challenge for amphibian conservation. Understanding juvenile demographics, movement ecology and response to mitigation structures is critical for expanding beyond short-term road mortality prevention to long-term mitigation (population persistence).

A 19-year study of a common toad population in south Dorset, UK, was carried out between 1980 and 1998. The daily arrival of sexually mature male and female toads at a breeding pond was recorded each year. The timing of the main arrival of toads at the breeding pond was highly correlated with the mean daily temperatures over the 40 days immediately preceding the main arrival. When the temperatures were higher than average, breeding occurred significantly earlier in the year than if they were either average or lower than average. During the study, the toad breeding seasons were early (2-13 February) in 5 years (1989, 1990, 1993, 1995, 1998), late (16-23 March) in 2 years (1986, 1996) and average (25 February-8 March) during the remaining 12 years. Evidence was found suggesting that common toads have a daylength threshold of about 9 h, below which the migration to the breeding pond does not occur. Evidence was also found indicating that common toads in southern England have a threshold temperature for activity of about 6°C and that the onset of breeding activity is highly correlated with the number of days during the 40 days prior to the main arrival at the breeding pond that were at or above this temperature. Predicting the start of the main breeding migration to a pond in any year may be possible by comparing the pattern of the 40-day running mean daily temperatures from 21 December the preceding year with those from previous years when the start of breeding activity is known. Although all five of the earliest recorded toad breeding years occurred during the last 10 years, and were associated with the occurrence of particularly mild winters, a significant trend towards earlier breeding in recent years compared with previous years was not found.

The secretion of glucocorticoids (GCs) is a classic endocrine response to stress. Despite that, it remains controversial as to what purpose GCs serve at such times. One view, stretching back to the time of Hans Selye, posits that GCs help mediate the ongoing or pending stress response, either via basal levels of GCs permitting other facets of the stress response to emerge efficaciously, and/or by stress levels of GCs actively stimulating the stress response. In contrast, a revisionist viewpoint posits that GCs suppress the stress response, preventing it from being pathologically overactivated. In this review, we consider recent findings regarding GC action and, based on them, generate criteria for determining whether a particular GC action permits, stimulates, or suppresses an ongoing stress-response or, as an additional category, is preparative for a subsequent stressor. We apply these GC actions to the realms of cardiovascular function, fluid volume and hemorrhage, immunity and inflammation, metabolism, neurobiology, and reproductive physiology. We find that GC actions fall into markedly different categories, depending on the physiological endpoint in question, with evidence for mediating effects in some cases, and suppressive or preparative in others. We then attempt to assimilate these heterogeneous GC actions into a physiological whole.

Roadside amphibian citizen science (CS) programmes bring together volunteers focused on collecting scientific data while working to mitigate population declines by reducing road mortality of pond-breeding amphibians. Despite the international popularity of these movement-based, roadside conservation efforts (i.e. big nights, bucket brigades and toad patrols), direct benefits to conservation have rarely been quantified or evaluated. As a case study, we used a population simulation approach to evaluate how volunteer intensity, frequency and distribution influence three conservation outcomes (minimum population size, population growth rate and years to extinction) of the spotted salamander (Ambystoma maculatum), often a focal pond-breeding amphibian of CS and conservation programmes in the United States. Sensitivity analysis supported the expectation that spotted salamander populations were primarily recruitment-driven. Thus, conservation outcomes were highest when volunteers focused on metamorph outmigration as opposed to adult in-migrationcontrary to the typical timing of such volunteer events. Almost every volunteer strategy resulted in increased conservation outcomes compared to a no-volunteer strategy. Specifically, volunteer frequency during metamorph migration increased outcomes more than the same increases in volunteer effort during adult migration. Small population sizes resulted in a negligible effect of volunteer intensity. Volunteers during the first adult in-migration had a relatively small effect compared to most other strategies. Synthesis and applications. Although citizen science (CS)-focused conservation actions could directly benefit declining populations, additional conservation measures are needed to halt or reverse local amphibian declines. This study demonstrates a need to evaluate the effectiveness of focusing CS mitigation efforts on the metamorph stage, as opposed to the adult stage. This may be challenging, compared to other management actions such as road-crossing infrastructure. Current amphibian CS programmes will be challenged to balance implementing evidence-based conservation measures on the most limiting life stage, while retaining social and community benefits for volunteers. Although citizen science (CS)-focused conservation actions could directly benefit declining populations, additional conservation measures are needed to halt or reverse local amphibian declines. This study demonstrates a need to evaluate the effectiveness of focusing CS mitigation efforts on the metamorph stage, as opposed to the adult stage. This may be challenging, compared to other management actions such as road-crossing infrastructure. Current amphibian CS programmes will be challenged to balance implementing evidence-based conservation measures on the most limiting life stage, while retaining social and community benefits for volunteers.

Although amphibians have relatively high rates of road mortality in urban areas, the conditions under which traffic threatens the survival of local amphibian populations remain unclear. In the Sandhills region of North Carolina (U.S.A.), we counted living and dead amphibians along two transects (total length 165 km) established on roads in areas with varying degrees of urbanization. We found 2665 individuals of 15 species, and amphibian encounter rates declined sharply as traffic and urban development increased. Regression-tree models indicated that 35 amphibians/100 km occurred on roads with <535 vehicles/day, whereas the encounter rate decreased to only 2 amphibians/100 km on roads with >2048 vehicles/day. Although mortality rate peaked at higher traffic levels (47% dead on roads with >5200 vehicles/day), the number of dead amphibians was highest at low levels of traffic. This suggests that areas where amphibian mortality is concentrated may actually contain the largest populations remaining on a given road transect.© 2010 Society for Conservation Biology.

The Florida panther (Puma concolor coryi) is one of the most endangered mammals, with the entire population estimated to consist of only 30-50 adult animals. Between 1978 and 1999, 73 free-ranging Florida panther carcasses were submitted for postmortem evaluation, of which 47 (64%) were radiocollared and 26 (36%) were uncollared cats. Overall, mortality of panthers > 6-mo-old was due to vehicular trauma in 25 (35%), intraspecific aggression in 19 (26%), illegal kill in seven (10%), research activities in two (3%), infectious diseases in two (3%), esophageal tear in one (1%), pleuritis in one (1%), pyothorax in one (1%), aortic aneurysm in one (1%), atrial septal defect in one (1%), and causes of death were undetermined in 13 (18%) due to autolysis. Of the 25 panthers that were killed by vehicular trauma, 20 (80%) died between October and April. This coincides with increased number of winter visitors to south Florida. Among radiocollared panthers, intraspecific aggression was the primary cause of mortality for 19 (41%) dead cats. Of these cats, 16 (84%) were males and 14 (88%) were either less than 3 or more than 8-yr-old. These animals were probably fighting to establish or retain territory. Among the 26 uncollared panthers, vehicular trauma was the primary cause of mortality and was responsible for 16 (62%) deaths. This study documents the causes of mortality and the age, sex, and seasonal mortality trends for both radiocollared and uncollared free-ranging endangered Florida panthers over a 21-yr-period.

During annual spring migration in Western Europe many amphibians are killed by traffic when they cross roads moving to reproduction sites. Especially in urban settings these roads are often equipped with street lighting. The response of amphibians to this light during migration is however poorly known. Street lighting may attract migrating amphibians increasing the risk of being struck by traffic. Using experimental illumination we tested whether light affected the migration and if adjustment of the spectral composition could mitigate effects. Barriers used to catch toads and help them cross roads safely were divided in 25 meter long sections and these were illuminated with white, green or red light or kept dark. The number of toads caught in each section was counted. Common toads avoided sections of roads that were illuminated with white or green light but not red light. Street light thus affects migrating toads but not as expected and red light with low levels of short wavelength can be used to mitigate effects.