Amphibian Movement Research Articles

Movement of amphibians in a habitat mosaic of agriculture landscape

Movement of amphibians in a habitat mosaic of agriculture landscape

Integrating fine-scale habitat suitability and hydrological structures to assess population connectivity for the Kaiser's mountain newt (Neurergus kaiseri) in southwest of Iran

The unique life cycle of amphibians, encompassing both aquatic and terrestrial stages, poses challenges for examining landscape connectivity within meta-populations. Their heavy reliance on water and limited mobility exacerbate these challenges. Fine-scale investigations of environmental factors contribute to understanding the distribution range and landscape connectivity of amphibian meta-populations. The present study examines the habitat suitability and connectivity among population cores of the Luristan newt (Neurergus kaiseri), a vulnerable (VU) species in southwest Iran. Using the Digital Elevation Model (DEM) and hydrological tools, the boundary of the study area was defined based on drainage basins and Maximum Entropy (MaxEnt), incorporating eight habitat variables to investigate the distribution range. Given that amphibians rely on moisture to move, DEM was used to calculate the Sediment Transport Index (STI) as a surrogate for suitable movement contexts. Using this index, the potential movement of sediment within streams across the landscape will be assessed. A high STI value can limit amphibian movement and shelter and therefore threaten the survival of larvae. Here, the STI was fuzzified based on the presence points using the s-shaped method and the symmetric membership function. The fuzzy overlay technique was employed using the habitat suitability map and OR logic, and finally, the inverse of the fuzzy map was used as landscape resistance. Sub-basins with at least two population cores in the drainage basin were identified and their linkage was established using the Linkage Mapper. Also, the depth and number of sinks along the linkage path of the population cores in each sub-basin were identified. The MaxEnt analysis highlighted the variables of elevation, distance from streams, and proximity to the forest as the most important factors influencing N. kaiseri. All Iranian populations of N. kaiseri were located within a single drainage basin. In this drainage basin, there were five sub-basins with more than two populations. Sub-basin 4 encompassed the largest population and exhibited the highest connectivity quality (29 flow rate). The maximum depth of the links between the population cores in this sub-basin reached 100 m from the surface, and a large segment of the population was located in the upper part of the sub-basin. 432 sinks were located between the population cores that helped conserve water, create microclimates, and supply moisture.The arrangement of the populations within the sub-basin, along with the presence of sinks and variations in linkage path depths created distinct conditions for population cores. These conditions significantly influenced the quality of the linkages. The results of the present study can serve as a valuable tool to identify and prioritize population cores and sub-basins for targeted conservation efforts.

Movements of the Glandirana Frogs in Japan and South Korea: A Strategy for Defining Geographical Movements of Amphibians

The Japanese islands were originally included in the Eurasian Continent as part of the southern and northern landmasses. The two landmasses were detached from the continent 18 million years ago. After that, the former was repeatedly connected to the Korean peninsula during glacial periods, but most of the latter was under seawater. Thus, all Japanese amphibians are undoubtedly derived from this nearby continent. However, it is unclear where the amphibians moved during the formation of the Japanese islands. To address the issue, we selected Glandirana rugosa as a representative of Japanese amphibians because this frog is the only species among amphibians in which nucleotide sequences of the mitochondrial genes and sex chromosome evolution have been deeply investigated. Then, we constructed time‐calibrated and RAxML phylogenetic trees based on nucleotide sequences of the mitochondrial genes of the Glandirana frogs in Japan and South Korea. Various sites were used to select SNP data from the Glandirana species and their sex chromosome evolution, and the cladograms we obtained suggest that ancient Glandirana frogs except for one group moved along with the southern landmass, when it was separated from the continent. The movements of the Glandirana frogs in Japan and South Korea obtained as results of this study will help scientists to understand the geographical changes that took place during the formation of the Japanese islands. This strategy is applicable to studying and understanding the movements of other amphibian species of the Eurasian and other continents.

Jumping between narrow banks: social spacing of the stream-dwelling montane frog, Crossodactylus trachystomus (Hylodidae)

Spacing patterns among individuals can reveal many ecological and behavioral features, such as responses to resource availability and social organization. The study of the amphibian movements still constitutes a gap in the knowledge of the animal ecology, and the general issues of the patterns of home range are poorly known to date. Herein, we evaluated the social spacing of a small stream-dwelling frog (Crossodactylus trachystomus), an endemic species from the Espinhaço mountain range in southeastern Brazil. We found that C. trachystomus shows one of the smallest home ranges among anurans, indicating a high philopatry level. We also showed that the home range size did not differ between females and males, neither was influenced by individual body size, which reveals a possible limitation for the use of larger home ranges in riparian systems. The distribution of home ranges showed high overlap among adult males, suggesting a weak territorial behavior or a possible “dear enemy effect” for this species. Beyond expanding the knowledge about the spatial ecology and behavior of the genus Crossodactylus, our outcomes contributed to the understanding of space use and the social organization of frogs, revealing spatial patterns that can be expected for other stream-dwelling frog species.

Evaluating fence-end treatments for migratory amphibians

Migratory amphibians require movements to complete their biphasic life cycle, often across altered landscapes fragmented by roadways, which can have severe consequences on their populations. To manage this threat, transportation agencies have begun to implement exclusion fencing to separate natural areas from the roadway to prevent wildlife-vehicle collisions. Although fences are an effective conservation tool, the tendency of animals to access the road by circumventing the fence ends, known as the fence-end effect, threatens to jeopardize management efforts to reduce road associated mortality. One strategy to lessen the impacts of the fence-end effect is to construct fence-end treatments to block amphibian movement and guide the animals to safe crossing locations. By using experimental fence arenas, we examined how nine amphibian species responded to two alternative fence-end structures: horizontal v-shape and perpendicular fence-end treatments. Using a generalized linear model framework, we found both fence-end treatments to be an effective strategy to reduce the impacts of the fence-end effect, with our predictor variable, fence-end treatment, explaining most of the variation in amphibian response. Structure effectiveness also started to improve by 20% with each 7°C increase in temperature, however, this was not significant. Despite these promising findings, we also found for each additional 312 s an amphibians spent attempting to navigate around the experimental fence resulted in a 25% decline in structure effectiveness, suggesting longer fences are not an adequate protection measure to combat the fence-end effect for amphibians. In addition, Anaxyrus americanus was not found to differ in their response, performing equally well to both experimental fence-end treatments. In contrast, Rana spp., Pseudacris crucifer, and Notopthalmus viridescens showed a greater response to the horizontal v-shape fence-end treatment compared to the perpendicular fence-end treatment. Variation in response for Ambystoma spp. could not be detected due to a small sample size; however, no individuals responded positively to the perpendicular fence-end treatment. Guidelines for amphibian fences should continue to incorporate fence-end treatments into the design and implementation to mitigate for the fence-end effect, and preferably angle the fence-ends inward in the horizontal v-shape pattern with the fence ends diagonal to the road for migratory amphibians.

Using Behavioral Characteristics to Design Amphibian Ladders for Concrete-Lined Irrigation Channels

Human-dominated landscapes have become a serious threat to amphibian populations worldwide. In such landscapes, concrete structures act as barriers to migration, fragmenting habitat and causing mortality. In China, concrete irrigation channels, which play an important role in agriculture, impede the movement of anuran amphibians. To promote the sustainable development of irrigated agriculture, we performed behavioral experiments to examine the ability of a common Chinese frog species (Pelophylax nigromaculatus) of four different body sizes to use corridors along a gradient of six different slopes to escape from irrigation channels. We found that body size was positively related with frogs’ ability to climb the ladders. Most frogs could not escape if the slope was ≥65 degrees, but all frogs could successfully navigate a ladder with a slope of 45 degrees. Based on our experimental results, we propose a simple improved design for amphibian ladders that would greatly improve the success of frogs in escaping from irrigation channels. This research is expected to provide scientific reference data and technical support for frog conservation in the study area, as well as the development of ecological restoration of irrigation districts throughout the world.

Evolution of seasonal land surface temperature trend in pond-breeding newt (Neurergus derjugini) in western Iran and eastern Iraq

BackgroundTemperature, as one of the effective environmental stimuli in many aspects of species life and ecosystems, can affect amphibians in many ways. Knowing and predicting temperature change and its possible effects on the habitat suitability and movements of amphibians have led many researchers to use climate change scenarios and species distribution models (SDMs). One of the important remote-sensing products that received less attention of conservation biologists is the land surface temperature (LST). Due to the small difference between LST and air temperature, this component can be used to investigate and monitor the daily and seasonal changes of habitats. This study aims to investigate the seasonal trend of LST in the habitat suitability and connectivity of the critically endangered newt (Neurergus derjugini) in its small distribution range, using the MODIS LST time series (2003 to 2021) and with the help of SDMs, Mann–Kendall (MK) and Pettitt non-parametric tests.ResultsIn the last decade, the increasing trend of LST versus its decreasing trends is obvious. Based on MK and Pettitt tests, in the winter and spring, with the decrease in latitude of 35.45° and increase in longitude of 46.14°, the core populations which are located in the southeast have experienced an increase in temperature. Considering the period time of breeding and overwintering, the continuity of winter and spring can be effective on the survival of adult newts as well as larvae in the microclimate. Linkages with the highest current flow between core populations in the winter and summer are the most likely to be vulnerable. At the level of habitat, the increase in LST is proportional to the trend of thermal landscape changes, and all seasons have had an increase in LST, but in winter and summer, the largest area of the habitat has been involved. By continuing the current trend, many high-altitude southern habitats in Iran will be endangered, and the species will be at risk of local extinction.ConclusionThe increasing trend of temperature in all seasons such as winter will affect many adaptations of the species and these effects are mostly evident in the southern parts of its distribution range therefore, captive breeding and reintroduction are recommended for the populations of these areas.

The effects of irrigation canals and roads as barriers to gene flow between Japanese brown frog (Rana japonica) breeding sites at a fine scale in a Satoyama landscape

Paddy fields in the agricultural landscape have become alternative habitats for natural wetland species. Habitat degradation, including habitat loss and fragmentation, is a major threat to members of Amphibia, which is a good indicator species for the Satoyama landscape. Recently, linear artificial structures, such as roads and railways, were recognized as factors inhibiting amphibian population persistence. Thus, irrigation canals and cement-walled streams may also affect amphibian movement and dispersal in the rural agricultural landscape termed Satoyama, which is now the main habitat for lowland wetland amphibians. However, there is limited information on such effects. Here, we focused on the Japanese brown frog (Rana japonica), which is an indicator species of the ecosystem health of the Satoyama landscape, to investigate the effects of irrigation canals on population structure. The barrier effects of roads and irrigation canals on gene flow between breeding sites were evaluated. We constructed a resistance map of the limiting factors to gene flow based on land use and frog movement and tested for correlations between cost and genetic distances. The habitat resistance values alone were insufficient to explain the genetic distances among breeding sites. Thus, we hypothesize that irrigation canals and roads have barrier effects on gene flow among amphibians in the Japanese Satoyama landscape.

Efficacy of permanent wildlife fences as barriers to amphibian movement

To mitigate habitat fragmentation and roadkill, roads are increasingly equipped with wildlife fences and underpasses. However, the effectiveness of such fences in preventing road access for amphibians has not been tested under controlled conditions. In 2019 and 2020, we tested the efficacy of full panel fences of differing material, height, and shape (presence/absence of an overhang), to prevent road access for adult and juvenile amphibians. We selected five species according to locomotion mode: Natterjack toads (runners), European green toads (short-distance jumpers), agile frogs (proficient jumpers), American tree frogs (proficient climbers) and smooth newts (climbers). We found that Natterjack and green toads were unable to cross a concrete fence with a height of 13 and 24 cm, respectively. Addition of a 10 cm overhang reduced the height required to prevent crossing further to 10 and 17 cm, respectively. The ability of these less agile species to cross a certain fence height depended on body length. By contrast, jumping agile frogs and climbing tree frogs were not stopped by the greatest fence height tested (40 cm). However, addition of the overhang stopped the climbing tree frogs at a concrete fence height of 35 cm. An alternative metal fence (with overhang) was tested with some species and performed similar to the concrete fence (with overhang). Finally, the greatest concrete fence height passed by climbing juveniles was 20 cm (smooth newts). Hence, to stop amphibians from road crossing, we recommend the construction of durable (concrete or galvanized metal) and well-maintained fences with a minimum height of 40 cm with a 10 cm overhang.

Multistate model to estimate sex‐specific dispersal rates and distances for a wetland‐breeding amphibian population

AbstractHow animals move across space and time in heterogeneous landscapes has important implications for the conservation of imperiled and dispersal‐limited taxa, such as amphibians. Wetland‐breeding amphibians are thought to exhibit strong site fidelity, but there is growing evidence that many species are more vagile than previously assumed. Few studies have quantified breeding dispersal probabilities or distances while also accounting for observational uncertainty, which means that resultant estimates could be biased or confounded with sampling intensity and other demographic rates (e.g., site‐ and time‐specific detection and survival probabilities). Here, we analyze data from a 6‐year capture–mark–recapture study on adult spotted salamanders (Ambystoma maculatum) conducted at 12 wetlands in central Pennsylvania to estimate population dynamics and population structure at multiple scales. We used a multistate, hidden Markov estimator to quantify sex‐specific site fidelity and breeding dispersal as a function of Euclidean distance between wetlands while accounting for imperfect detection. We estimated short‐timescale movements (i.e., those that occur within a single breeding season) and longer timescale movements (i.e., those that occur among breeding seasons) to determine if dispersal rates and distances differed. We found that interannual site fidelity of males varied among wetlands and was positively associated with population density. Females exhibited higher interannual site fidelity and dispersed further than males between breeding seasons. Within breeding seasons, we found that up to 6% of males dispersed to a new wetland each day. Our study is the first to directly compare amphibian breeding dispersal probabilities and distances at multiple scales and provides a robust framework for improving inference on the spatial and temporal patterns of amphibian movement.

Does Exposure to Predator Cues Influence Movement Behavior of Postmetamorphic Juvenile Rana aurora?

Exposure to predators during early life stages can alter behavioral and physical traits during ontogeny. This is important for biphasic amphibian species because juvenile movement behavior can be shaped by carry-over effects of the larval environment and direct effects of abiotic conditions in terrestrial habitats. We explored the interaction of aquatic predator cue exposure, juvenile morphology, and abiotic terrestrial conditions on the movement behavior of postmetamorphic Northern Red-legged Frogs (Rana aurora). We quantified carry-over effects of aquatic predator cues and direct effects of substrate conditions on individual movement behavior using a combination of seminatural enclosed runways and powder tracking assays. We found a latent effect of aquatic condition, such that crayfish-exposed individuals had greater relative body condition at metamorphosis, and all predator-exposed individuals had larger body lengths relative to controls. Terrestrial conditions were the dominant factor shaping movement behavior. During runway movement assays, individual conditional movement displacement was likely greater in dry soil and low humidity conditions than in moist conditions with high humidity. For nocturnal powder tracking assays, individuals were more likely to have greater path distances during warmer temperatures, whereas paths were less meandering in cooler, dry conditions. Morphologically larger individuals moved greater distances only during the powder tracking assays. We observed latent effects of aquatic predator exposure on juvenile morphology; however, the relationship between these changes and the relative importance of direct environmental conditions in shaping movement behavior is unclear. Our results demonstrate the interconnected nature of aquatic and terrestrial environments in shaping the movement of juvenile amphibians.

Verification of the Detection Performance of Drone Radio Telemetry for Tracking the Movement of Frogs

Elucidating the various behavioral and ecological uses of animal habitats is the basis for the conservation and management of animal species. Therefore, tracking the movement of animals is necessary. Biotelemetry is used for tracking the movement of animals. By mounting a radio telemetry receiver and antenna on a drone, the time and labor required for surveying animals can be reduced. In addition, it is easy to track difficult-to-reach areas such as rice paddies and forests, and the environment is not invaded by the survey. We think that this drone radio telemetry will be the best method for tracking the movement of small amphibians, such as frogs. However, in order to put the method to practical use, the accuracy of the system needs to be verified. Approximately 26 ha of area in Sogabe, Kameoka City, Kyoto Prefecture, Japan was investigated in this study. We selected and validated the location where frogs are likely to enter farmlands. The location where the detection of movement is expected to be stable are 5 cm deep areas in the soil, gaps in masonry, and under plastic bags, whereas areas in which the detection is likely to be unstable are areas deeper than 5 cm in the soil, covered concrete channels, and grass. By calculating the geographic center, the location of the nanotag could be estimated with an accuracy of less than 16 m. We successfully showed that the drone radio telemetry system used in this study is capable of detecting and tracking the movement of animals with high spatial and temporal resolutions. However, we suggest that the detection of movement may be interrupted depending on the location of the target animal and more than three detections are needed to guarantee the accuracy of the estimation.

Human disturbance causes widespread disruption of animal movement.

Disturbance and habitat modification by humans can alter animal movement, leading to negative impacts on fitness, survival and population viability. However, the ubiquity and nature of these impacts across diverse taxa has not been quantified. We compiled 208 studies on 167 species from terrestrial and aquatic ecosystems across the globe to assess how human disturbance influences animal movement. We show that disturbance by humans has widespread impacts on the movements of birds, mammals, reptiles, amphibians, fish and arthropods. More than two-thirds of 719 cases represented a change in movement of 20% or more, with increases in movement averaging 70% and decreases -37%. Disturbance from human activities, such as recreation and hunting, had stronger impacts on animal movement than habitat modification, such as logging and agriculture. Our results point to a global restructuring of animal movement and emphasize the need to reduce the negative impacts of humans on animal movement.

Modeling habitat connectivity in support of multiobjective species movement: An application to amphibian habitat systems

Reasoning about the factors underlying habitat connectivity and the inter-habitat movement of species is essential to many areas of biological inquiry. In order to better describe and understand the ways in which the landscape may support species movement, an increasing amount of research has focused on identification of paths or corridors that may be important in providing connectivity among habitat. The least-cost path problem has proven to be an instrumental analytical tool in this sense. A complicating aspect of such path identification methods is how to best reconcile and integrate the array of criteria or objectives that species may consider in traversal of a landscape. In cases where habitat connectivity is thought to be influenced or guided by multiple objectives, numerous solutions to least-cost path problems can exist, representing tradeoffs between the objectives. In practice though, identification of these solutions can be very challenging and as such, only a small proportion of them are typically examined leading to a weak characterization of habitat connectivity. To address this computational challenge, a multiobjective optimization framework is proposed. A generalizable multiobjective least-cost path model is first detailed. A non-inferior set estimation (MONISE) algorithm for identifying supported efficient solutions to the multiobjective least-cost path model is then described. However, it is well known that unsupported efficient solutions (which are equally important) can also exist, but are typically ignored given that they are more difficult to identify. Thus, to enable the identification of the full set of efficient solutions (supported and unsupported) to the multiobjective model, a multi-criteria labeling algorithm is then proposed. The developed framework is applied to assess different conceptualizations of habitat connectivity supporting amphibian movement in a wetland system. The results highlight the range of tradeoffs in characterizations of connectivity that can exist when multiple objectives are thought to contribute to movement decisions and that the number of unsupported efficient solutions (which are typically ignored) can vastly outweigh that of the supported efficient solutions.

Методи трекінгу земноводних

ntroduction: In this article, we present a literature review of modern, most common, and useful methods of amphibian tracking. Amphibians are the most sensitive group of animals and near 41 % of species are under the risk of extinction. Therefore, the research of spatial movements of amphibians is one of the most topical tasks of modern herpeto­logy. The information about the use of space is needed for practical protection of sensitive species of amphibians, for planning of protected areas, estimation of the potential danger for some groups of animals when designing infrastructure objects, such as roads. The movement studies gained popularity and have been undertaken since the second part of the 20th century. Such growth in the number of studies is related to the recent advances in radio-electronic technology that contributed to the creation of a range of instruments for automatic or semi-automatic tracking of individual animals. Unfortunately, most of such methods are still too expensive for scientists from developing countries. Thus, classical methods are still widely used. Results: We describe six methods of amphibians tracking: radioisotope tracking, automated radio telemetry, harmonic direction finding, radio frequency identification, fluorescent powder, spool tracking. Each of these methods allows collecting detailed information about spatial movements of individuals. Many of these tracking methods require using of a special tag, which is attached to an animal and used for its further detection. Different types of tags have identical functions but are based on different principles of use. Two of the described methods do not require using of tags and are cheap. These are fluorescent powder and spool tracking. In the article, we provide many links to grant programs and places where special equipment can be found. Conclusions: As a result of literature review, we created a table with concise information about all the described methods. Using this table one can choose the best method for an experiment. Keywords: amphibians, radiotelemetry, fluorescent powder, radioisotope tracking, spool tracking

Modelling the contribution of ephemeral wetlands to landscape connectivity

Habitat loss and fragmentation continue to drive declines of amphibian populations. Maintaining connectivity between aquatic and terrestrial habitats and across wetlands is critical to amphibian conservation, particularly in regions where climate change may exacerbate habitat loss. Our objective was to study the impact of climate- and human-driven losses in ephemeral wetlands on functional connectivity for amphibians, using the endangered western tiger salamander (Ambystoma mavortium) in British Columbia, Canada as a case study. Land use data and dispersal characteristics for the western tiger salamander were used to develop a spatially-explicit individual-based model of amphibian movement. The model was configured to explore connectivity under three climate scenarios (a wet, average, and dry year), and a land management scenario in which only known breeding sites are conserved. We used a spatial network analysis to identify key ephemeral wetlands that connect otherwise isolated sub-networks across the landscape and probable movement paths between wetlands and the upland terrestrial habitat. Our results illustrate the importance of conserving ephemeral wetlands as stepping stones. We argue that a landscape approach to wetland conservation, rather than just conserving known breeding sites, is essential for retaining viable amphibian populations in a context of human induced habitat loss and climate change.

AMPHIBIAN MOVEMENT ACROSS A NEW RESIDENTIAL ROAD IN WESTERN WASHINGTON STATE

In this exploratory study, we investigated amphibian movement across a new 1.4-km residential road system adjacent to a wetland complex in Thurston County, Washington. We implemented this study prior to home construction, and before traffic levels associated with occupancy occurred. Our purpose was to document pond-breeding amphibian movement patterns to identify safe-crossing recommendations. One 24-h walking survey was conducted per month from October to December 2008, and in February 2009. We observed 7 native amphibian species and tallied 225 amphibian observations. The data showed differences in autumn to winter migration timing and direction relative to the wetland complex among species, sexes, and life stages. Most adults were moving toward the wetlands, whereas most juveniles were moving away. The highest number of observations occurred during the 00:00 to 03:59 h dark interval, corresponding with lowest local traffic volume. Nearly all observations for Northern Red-legged Frog (Rana aurora), Pacific Treefrog (Hyliola regilla), Long-toed Salamander (Ambystoma macrodactylum), and Northwestern Salamander (Ambystoma gracile) occurred after dark. However, Rough-skinned Newt (Taricha granulosa) peak movement occurred during daylight, corresponding with the highest traffic volume. We documented diffuse movement throughout the road system. Spatial analyses highlighted 2 significant crossing hot spots, including a 1.8-m diameter culvert. This study illustrates the importance of understanding the spatial and temporal patterns in pond-breeding amphibian migrations to effectively plan and implement measures to reduce amphibian road mortality. Prior to new development, we encourage proactive planning, such as connectivity, traffic, and traffic calming analyses to identify amphibian migration locations and reduce mortality. In areas with existing roads, such as the study site, we suggest implementation of mitigation measures paired with effectiveness monitoring.

The integrative effects of behavior and morphology on amphibian movement.

Animal movement and dispersal are key factors in population dynamics and support complex ecosystem processes like cross‐boundary subsidies. Juvenile dispersal is an important mechanism for many species and often involves navigation in unfamiliar habitats. For species that metamorphose, such as amphibians, this transition from aquatic to terrestrial environments involves the growth and use of new morphological traits (e.g., legs). These traits strongly impact the fundamental ability of an organism to move in novel landscapes, but innate behaviors can regulate choices that result in the realized movements expressed. By assessing the integrative role of morphology and behavior, we can improve our understanding of juvenile movement, particularly in understudied organisms like amphibians. We assessed the roles of morphological (snout‐vent length and relative leg length) and performance (maximal jump distance) traits in shaping the free movement paths, measured through fluorescent powder tracking, in three anuran species, Pacific treefrog (Hyliola regilla), Western toad (Anaxyrus boreas), and Cascades frog (Rana cascadae). We standardized the measurement of these traits to compare the relative role of species' innate differences versus physical traits in shaping movement. Innate differences, captured by species identity, were the most significant factor influencing movement paths via total movement distance and path sinuosity. Relative leg length was an important contributor but significantly interacted with species identity. Maximal jump performance, which was significantly predicted by morphological traits, was not an important factor in movement behavior relative to species identity. The importance of species identity and associated behavioral differences in realized movement provide evidence for inherent species differences being central to the dispersal and movement of these species. This behavior may stem from niche partitioning of these sympatric species, yet it also calls into question assumptions generalizing anuran movement behavior. These species‐level effects are important in framing differences as past research is applied in management planning.

Mitigating the effects of a road on amphibian migrations: a Scottish case study of road tunnels

The ever-growing pace of road construction worldwide has become a serious concern for wildlife and natural habitats, resulting in habitat fragmentation and increasing wildlife road fatalities. For amphibians, which are undergoing population declines worldwide, mitigation measures such as road under-passages linked to amphibian-proof fencing may be an effective conservation tool, aiming to reconnect natural habitats and reduce wildlife fatalities. This study assessed the efficacy of road tunnels in a recently developed area by Frankfield Loch, Stepps, North Lanarkshire. Three amphibian tunnels, plus fencing, were put in place during 2010 following the construction of a road in 2006 which separated the loch from a substantial area of marshland, including ponds. In 2015 and 2016, we used custom-made time-lapse cameras within the tunnels to automatically monitor amphibian movements and conducted frog spawn surveys. Numbers of common frogs (Rana temporaria), common toads (Bufo bufo) and newts (Lissotriton spp.) using the tunnels were substantial in both years, though the number of toads decreased significantly between years. We found many frog spawn clumps in the marsh ponds, but rather fewer in the loch. A period of road repair in 2015 was linked with both road mortalities and a change in the pattern of tunnel usage. Additionally, amphibians showed a daily cycle of activity, with nocturnal movements most common. These results indicate important connectivity and usage of both the marsh and the loch, and suggest that this can be effectively sustained through the proper maintenance of tunnels and fencing, which also minimises road mortalities. It remains unknown, however, what proportion of the population crosses the road via the tunnels and how that compares with movements prior to road construction.

The influence of environmental factors on pond activity of aquatic red-spotted newts Notophthalmus viridescens

ABSTRACTMany important components of animal behavior, growth, and reproduction are tightly linked to environmental conditions, particularly for ectothermic freshwater organisms. For amphibian species, factors such as temperature and rainfall can be physiologically limiting and alter activity levels. The effects of environmental conditions on terrestrial amphibian movement have been well characterized, but less is known about the importance of these factors in aquatic habitats. Here we investigate the impact of temperature and rainfall on the activity of a pond-dwelling amphibian using capture patterns of aquatic adult red-spotted newts (Notophthalmus viridescens). Data on newt captures, air temperature, and rainfall were collected for 6 years (2009, 2011, 2013–2016) during the winter breeding season at a wetland in the Piedmont region of North Carolina, USA. In 2016, we collected more detailed data on the size and sex of captured newts, as well as recording water temperature. Overall, temperature played a significant role in determining newt activity, while rainfall had little effect. As expected, and consistent with findings on amphibian activity in terrestrial systems, newt captures increased with increasing air temperature. During the 2016 breeding season we found sex-based changes in activity in response to temperature, with a higher proportion of males captured during warmer temperatures and a reduction in the male capture bias during colder temperatures. We found no evidence of size-based shifts in activity in response to temperature. This study increases our knowledge of amphibian responses to temperature while in aquatic habitats. Although the duration of time spent in aquatic habitats can be highly variable between species, these breeding locations are critical for the persistence of populations and activity levels, and reproductive success in these wetlands can be highly impacted by future changes in environmental conditions.