Distribution Of Salamanders Research Articles

Spatial segregation among age classes in cave salamanders: habitat selection or social interactions?

AbstractWithin species, individuals with different sexes, morphs and age classes often show spatial segregation. Both habitat selection and social processes have been proposed to explain intraspecific spatial segregation, but their relative importance is difficult to assess. We investigated spatial segregation between age classes in the cave salamanderHydromantes(Speleomantes)strinatii, and used a hypothetico‐deductive approach to evaluate whether social or ecological processes explain segregation pattern. We recorded the location and age class of salamanders along multiple caves; we measured multiple microhabitat features of different sectors of caves that may determine salamander distribution. We assessed age‐class segregation, and used generalized mixed models and an information‐theoretic framework, to test if segregation is explained by social processes or by differences in habitat selection. We found significant age‐class segregation, juveniles living in more external cave sectors than adults. Multiple environmental features varied along caves. Juveniles and adults showed contrasting habitat selection patterns: juveniles were associated with sectors having high invertebrate abundance, while adults were associated with scarce invertebrates and low temperature. When the effect of environmental features was taken into account, the relationship between juveniles and adults was non negative. This suggests that different habitat preferences, related to distinct risk‐taking strategies of age classes, can explain the spatial segregation. Juveniles require more food and select more external sectors, even if they may be risky. Conversely, adults may trade off food availability in favour of safe areas with stable micro‐climate.

Do cave salamanders occur randomly in cavities? An analysis with Hydromantes strinatii

Underground environments are increasingly recognised as important habitats for the distribution of certain amphibians. However, very few analyses tested whether amphibians occur randomly in underground environments, or they select cavities with specific environmental features. We assessed the distribution of the cave salamanderHydromantes(Speleomantes)strinatiiin an area of NW Italy during summer, and analysed relationships between salamander distribution and multiple cave features, considering parameters describing both the biotic and the abiotic environment. Using visual encounter surveys, species’ detection probability was high, indicating that this technique provides reliable information on distribution. Salamanders were associated to caves with cold and humid microclimate, presence of wet walls, and hosting large numbers ofMetaspiders. The association with less luminous caves was close to significance. Distribution data were not affected by spatial autocorrelation, suggesting that cave features are more important than the proximity to other occupied caves in determining the pattern of occupancy. Caves are heterogeneous environments: cave salamanders are strongly related to the features of underground environments. Food availability and abiotic features are major determinants of suitability for cave salamanders. Inter-correlation among biotic and abiotic cave features makes it complex identifying the role of factors determining species distribution, but quantitative analyses and PCA help to unravel the cave habitat requirements for amphibians.

An Assessment of Distribution Patterns of Terrestrial Salamanders in the Central Appalachians Using Two Landscape Models

Abstract Conservation of terrestrial salamanders requires consideration for landscape-level features and processes; and, therefore, tools are needed to support planning at large spatial scales. We assessed terrestrial salamander distribution patterns using an existing salamander data set and two previously developed landscape-level spatial tools, a landscape classification (LC) model and flow accumulation (FLOW) model, both based on 100-m2 pixels. The LC model assigned each pixel to one of eight categories defined by slope, aspect and landform. The FLOW model assigned each pixel to one of five categories based on the number of 100-m2 cells that drained into a given cell. Salamander data had been collected in the Allegheny Mountains of West Virginia during 2001–2003 on 543 100-m2 plots located along random transects. Using area-constrained searches we collected 1879 individuals of eleven species. Plethodon cinereus, Desmognathus ochrophaeus, D. monticola and D. fuscus represented 92.8% of all captures. All...

Substrate preference of eastern red-backed salamanders, Plethodon cinereus: A comparison of deciduous and coniferous substrates

AbstractForest tree composition can affect the distribution and abundance of terrestrial salamanders. We examined the effect of leaf litter type (deciduous or coniferous) and soil type (deciduous and coniferous) on red-backed salamander (Plethodon cinereus) substrate choice using a series of laboratory experiments. Salamanders preferred deciduous leaves over coniferous pine needles and the deciduous soil/deciduous leaf litter combination over all others. In addition, our results suggest that leaf litter type may be more important than soil type in influencing salamander substrate preference in our study. Our results suggest that behavioural avoidance may partially explain differences in P. cinereus abundances in deciduous and coniferous forest habitats.

Update on the Range and Distribution of Blue-Spotted Salamanders in Manitoba

Update on the Range and Distribution of Blue-Spotted Salamanders in Manitoba

IDENTIFICATION OF EURYHELMIS COSTARICENSIS METACERCARIAE IN THE SKIN OF TOHOKU HYNOBIID SALAMANDERS (HYNOBIUS LICHENATUS), NORTHEASTERN HONSHU, JAPAN

Since 2000, cutaneous nodular lesions were observed in Tohoku hynobiid salamanders (Hynobius lichenatus) in the northern Abukuma Mountains, northeastern Honshu, Japan. The distribution of diseased salamanders has expanded, along with the increasing severity of the disease. Samples (foreleg, hindleg, and tail) from five diseased salamanders caught in the spring of 2009 contained 11 to 383 metacercarial cysts (0.43-0.48 mm in diameter) per individual. Experimental inoculations of the metacercariae into rats (Rattus norvegicus) resulted in the development of pentagonal adults with intrauterine eggs that were collected at 3 days, 2 wk, and 5 wk postinoculation. Although adults obtained from rats were smaller, the flukes were morphologically similar to Euryhelmis costaricensis, recorded from Japanese martens (Martes melampus) in northeastern Honshu. The ribosomal RNA gene sequences of the metacercariae collected from salamanders and the E. costaricensis collected from a Japanese marten were identical, confirming the morphology-based species identification. Environmental changes responsible for the increased frequency of diseased salamanders and the increased parasite load are unknown, although increases in feral populations of introduced raccoons (Procyon lotor) and American minks (Neovison vison) may be associated.

Effects of predaceous and nonpredaceous introduced fish on the survival, growth, and antipredation behaviours of long-toed salamanders

Simultaneous introduction of complex suites of exotic organisms into indigenous populations have poorly known magnitudes and consequences. We compared the effects of introduced piscivorous rainbow trout ( Oncorhynchus mykiss (Walbaum, 1792)) and nonpiscivorous fathead minnows ( Pimephales promelas Rafinesque, 1820) on growth, survival, susceptibility to predation, and antipredator behaviours of naïve long-toed salamanders ( Ambystoma macrodactylum Baird, 1850). Trout reduced salamander hatchling and larvae survival to nearly zero in predation trials and caused a 39% reduction in salamander survival within outdoor mesocosms. Salamander larvae did not increase their refuge use or alter activity patterns in the presence of trout. These results imply that allotopic distributions of trout and salamanders observed in several field surveys likely result from the inability of larvae to recognize introduced predators as a threat. Minnows also caused significant reductions in salamander survival (41%) and growth (37%) in mesocosms, and exposure to minnow cues caused larvae to spend more time within a refuge. Reduced salamander survivorship and growth in the mesocosms was likely due to competition for limiting zooplankton and (or) cannibalism. These results indicate that introductions of small-bodied, nonpiscivorous fishes can reduce amphibian survival and growth to at least the same extent as introduced trout.

Factors Influencing Occupancy Patterns of Eastern Newts across Vermont

Of the threats facing amphibian populations today, habitat transformation resulting from land use is among the most pressing. Although conservation of pond-breeding salamanders clearly requires protection of breeding ponds and their surrounding habitat, little is known about the effects of land use and other factors on the occurrence of salamanders in the dispersal/terrestrial phase of their life cycle. To determine these effects, we surveyed populations of Eastern Newts (Notophthalmus viridescens) at 551 stations across Vermont and modeled salamander distribution as a function of environmental variables hypothesized to influence site occupancy. We developed a set of 12 models based on seven a priori hypotheses of site occupancy. We hypothesized that occupancy was influenced by (1) amounts of available habitat types, (2) arrangement of these habitat types, (3) geographic position, (4) housing density, (5) road density, (6) short-term changes in habitat distribution, or (7) habitat structure at the stand level. We used a single-season occupancy model to rank and compare the 12 models. A total of 232 Eastern Newts was detected at 82 of 551 stations. Of the 12 models, amount of habitat within 0.5 km of the survey station best represented the field data. Strong effects were indicated for developed land (−), open water ( ), and forest ( ) cover. Given a survey station with average forest and open water characteristics, stations with >5% developed land classes within a 0.5-km buffer had a very low probability of occupancy. Further research is needed to determine the direct role of development on occupancy patterns.

Distribution of long-toed salamanders and introduced trout in high- and low-elevation wetlands in southwestern Alberta, Canada

Several species of trout have been introduced into most wetlands within the mountain and foothill regions of southwestern Alberta, Canada. In this study, we used standard survey methods to evaluate the distribution of long-toed salamander (Ambystoma macrodactylum) larvae relative to introduced trout within 27 low-elevation wetlands and 30 high-elevation wetlands in Waterton Lakes National Park and the adjacent Castle Special Management Area. Results provided indirect evidence of salamander displacement by trout. At high elevations, salamander larvae were not detected in any of the sites that contained trout. The complete allotopy between trout and long-toed salamanders within high-elevation sites supports previous studies completed within the core of this species' range, further documenting the widespread negative impacts of introduced trout on native amphibians in upper basins. Similarly, salamander larvae were present in each of the low-elevation wetlands that lacked trout; they co-occurred in only 4 of 27 low-elevation wetlands. Allotopy within lower elevation sites is particularly important from a conservation perspective because, relative to populations in high-elevation wetlands, these populations tend to contain individuals with rapid growth and high dispersal rates.

INTERGENERIC SALAMANDER INTERACTIONS ACROSS AN ECOTONE

Although many field experiments have examined interactions among terrestrial salamanders or among semi-aquatic salamanders, virtually no research has examined potential interactions among salamander species across ecotones. Past research has indicated that numerous factors may influence salamander distributions, including competition, predation, and abiotic factors. We conducted a field removal experiment to investigate potential interactions among salamanders across the steam-woodland ecotone and to determine the effects of such interactions on community structure. We used removals of a terrestrial salamander, Plethodon cinereus, and/or several species of semi-aquatic salamanders of the genus Desmognathus to investigate potential interactions between these genera and the semi-aquatic salamander Eurycea cirrigera. Although removals did not significantly decrease numbers of P. cinereus or Desmognathus on plots, distribution of E. cirrigera shifted unexpectedly closer to streams in response to removals of P...

Dusky salamanders ( Desmognathus, Plethodontidae) from the Coastal Plain: Multiple independent lineages and their bearing on the molecular phylogeny of the genus

Recent phylogenetic reassessment of the lungless salamanders (Plethodontidae) confirmed a major life-history reversal—from direct development to an aquatic larval stage—in the dusky salamanders ( Desmognathus) of eastern North America. This reversal initiated high rates of lineage accumulation, reputedly generating the species richness and ecological breath that now characterize Desmognathus. Certain important aspects of the radiation, e.g., ecomorphological evolution, have been identified through intense sampling effort of Appalachian Highland lineages. However, the research preoccupation on montane species has left overlooked a significant component of dusky salamander distribution—the Coastal Plain. We present the first molecular phylogeny for Desmognathus to incorporate extensive coverage from the Atlantic and Gulf coastal plains. We examined 38 Coastal Plain populations in conjunction with 45 additional populations, representing 16 of the 19 nominal species. Bayesian analysis of 88 mitochondrial cox1 haplotypes diagnosed eight independent population lineages within the Coastal Plain, a number at odds with the region’s three currently recognized species. Desmognathus has apparently experienced a complex biogeographic history in this physiographic region, one involving multiple invasions and several ecological transitions from lotic to lentic habitats.

Walking Trails in a Nature Preserve Alter Terrestrial Salamander Distributions

Humans are increasingly altering forested habitats, in part by forestry practices, but also in more subtle ways such as creation of recreational trailways through forested areas, especially in nature preserves and parks. The effect of these trails on wildlife has only recently begun to be addressed. In this paper, I hypothesize that trails alter the distribution of terrestrial salamanders in forested habitats. The routine clearing of fallen trees from trailways may act to increase microhabitat availability for salamanders around trails, and thus move salamanders closer to the trails, or salamanders may simply stay away from trails in general to avoid disturbance associated with humans. To address this issue, I conducted a 3-month study in a nature preserve in northeast Georgia, using standardized, paired surveys of cover objects (logs and stones) in 78 m2 plots along trails and in similar plots 25 m away from trails. I found significantly more logs in along-trail plots versus off, but there was no difference in stone abundance. There were more salamanders under logs in along-trail plots versus off-trail, but on a per-log basis, there was no significant difference between along-versus off-trails, suggesting that trails result in more microhabitats for salamanders around them, not that salamanders move closer to trails per se.

Influence of Headwater Site Conditions and Riparian Buffers on Terrestrial Salamander Response to Forest Thinning

Abstract Although thinning of young, even-aged forests may accelerate the development of characteristics associated with mature forests, in the short term it may negatively affect some taxa, including terrestrial salamanders. Preexisting site conditions, including down wood, and forest management measures, such as riparian buffers, may moderate these effects, but these relationships are poorly understood. To explore whether down wood and riparian buffer widths might influence short-term responses to thinning, we sampled salamanders using ground searches before and during the first 2 years after experimental thinning at two 45- to 65-year-old headwater forest sites in western Oregon that differed in down wood volume. Prethinning distributions of terrestrial salamanders overlapped one- and two-tree height riparian buffers, and except for red-backed salamanders, overlapped very little with narrower streamside or variable-width buffers. At the site where down wood volume was low, captures of ensatina (Ensatina eschscholtzii Gray) and western red-backed salamanders (Plethodon vehiculum Cooper) both declined by 40% in thinned areas. In contrast, captures of ensatina and Oregon slender salamanders (Batrachoseps wrighti Bishop) were not significantly affected by thinning at the site where down wood volume was high. Our results suggest that site conditions, such as down wood volume, and riparian buffers may influence the effect of thinning on terrestrial salamanders, and demonstrate the tight linkage among management of aquatic, riparian, and upslope resources in headwater forests.

Illustrating catchment-reach coupling: the effect of discharge type on the distribution of larval fire salamanders

The role of stream discharge regime in the distribution of larval fire salamanders was investigated in Lower Austria. To define the types of discharge we used the database provided by the Hydrographical Annual and for salamander distribution the Atlas zur Verbreitung und Okologie der Amphibien und Reptilien in Osterreich (CABELA et al. 2001), supplemented'by our own observations. Based on 62 (sub-)catchments, Spearman's rank correlation coefficients (SRCs) between monthly Parde coefficients and monthly larval records were low ( 0.05 -P 0.86), P-levels and SRCs indicated a high degree of synchronization between monthly Parde coefficients and monthly larval records. The percentage of catchments inhabited by salamanders was highest within WIP and PLN discharge types, intermediate in NIP and virtually zero in WIN, GEN and SOP types. In PLN and WIP, the times of high discharge occur early in the year, and baseflow is reached again during larval abundance peaks. This pattern also ensures that temporary waterbodies have been re-filled by the preceding floods. In NIP catchments, high discharge and larval abundance peaks coincide, whereas in SOP catchments the discharge peak starts after the larval abundance has peaked.

An assemblage of salamanders in the southern Appalachian Mountains revisited: Competitive and predatory behavior?

Salamander communities have been excellent model systems for investigating the effects of competition and predation on community structure. Researchers have frequently examined the roles of competition and predation in terrestrial or semi-aquatic communities of salamanders, but have rarely examined the influence of these factors between these communities. We conducted mesocosm and laboratory behavioral experiments (1) to test hypotheses, derived from by a previous laboratory study, in a semi-natural setting and (2) to formulate new hypotheses regarding novel species-pair combinations. Our mesocosm experiments did not support a previous hypothesis of predation by Desmognathus fuscus (a semi-aquatic species) on Plethodon cinereus (a terrestrial species), but did support a prediction that P. cinereus would avoid D. fuscus. We predicted that behavioral experiments between pairs of semi-aquatic species would demonstrate predatory behavior by D. fuscus toward E. cirrigera and aggressive behavior by D. ochrophaeus toward Eurycea cirrigera; we did not find strong evidence for either predation or aggression. This finding was surprising given the similar activity patterns and dietary habits of these species. Although we predicted that Desmognathus might influence local distributions of heterogeneric salamanders through interspecific aggression in a manner similar to that seen within this genera, we found that both D. fuscus and D. ochrophaeus displayed much less aggression than expected. However, D. fuscus, in particular, appears to induce avoidance behavior in both P. cinereus and E. cirrigera without evidence of predation or excessive aggression, indicating that interference competition may be an important factor in structuring plethodontid communities.

Evaluating biotic and abiotic influences on torrent salamanders in managed forests of western Oregon

To better understand the distribution and abundance of headwater-stream salamanders in managed conifer forests, we examined relationships between Cascade torrent salamanders (Rhyacotriton cascadae) and biotic and abiotic habitat attributes at landscape and within-stream levels in western Oregon, USA. In 2001 we found 145 torrent salamanders in 25% of 59 headwater (first-order) streams from randomly selected 2.58-km2 sections of the study area. Landscape-level variation in torrent salamander distribution and relative abundance were related to the age of adjacent riparian forests and to the landform features parent geology and stream aspect. In 2002 we conducted a more detailed study of salamander occurrence and abundance within 49 10-m stream reaches, stratified by gradient, that were randomly selected from 15 streams known to contain salamanders. We recorded 475 salamanders from 33 (67%) of the stream reaches. Akaike's Information Criterion (AIC) model selection indicated that a streambed substrate model best explained salamander occupancy in stream reaches, but a model containing only the parameter distance to stream origin and another model containing abiotic landform features also received strong empirical support. In contrast, the distance to stream origin model was the best candidate model explaining reach-level salamander abundance. However, 2 additional models explaining abundance, including one that discriminated between the northern and southern portions of our study area and another that reflected stream reach habitat parameters, also received strong empirical support. Physical features of stream habitats appear to have an important influence on the distribution and abundance of torrent salamanders at multiple spatial scales, and these parameters should be addressed when designing management strategies (e.g., riparian buffers) to conserve these species.

Altered drying regime controls distribution of endangered salamanders and introduced predators

Introduction of invasive species has been implicated in the decline of many native species. However, the mechanisms that underlie successful invasion and species replacement are often poorly understood. We tested the hypothesis that disruption of the natural disturbance regime can facilitate invasion of habitats, resulting in the exclusion of native species. In Arizona’s San Rafael Valley, cattle ponds designed to hold water year-round have replaced seasonal marshes, and this altered drying regime has facilitated invasion by disturbance-intolerant fish and bullfrogs that negatively affect native Sonoran tiger salamanders. We investigated the relationships among pond drying regime, presence of introduced fish and bullfrogs, and presence of tiger salamander populations in 42 ponds. Both fish and breeding bullfrog populations disappeared following pond drying. Pond drying in cattle ponds negatively affected salamanders, but not to the same extent that it affected fish and bullfrogs. Metamorphosed bullfrogs ate salamander larvae in laboratory and field experiments, and the risk of local extinction among salamander populations was increased by introduced fish. Once fish eliminated salamanders from an aquatic habitat, salamanders seldom reappeared unless fish were killed by drying. Simple models were developed to predict change in salamander, fish, and bullfrog distributions with changes in cattle pond drying frequency. The models show that decreases in pond drying frequency could negatively affect salamanders by leading to a community dominated by disturbance-intolerant fish and bullfrogs, but increased drying frequency could negatively affect salamander populations by preventing salamander breeding. These results suggest that manipulation or restoration of disturbance regimes may be a powerful tool in managing for native species threatened by biotic invasions.

Forecasting Climate Change Effects on Salamander Distribution in the Highlands of Central Mexico1

ABSTRACTA generalized decline of amphibian populations is occurring worldwide. The causes for such a decline are not completely understood; however, climate change has been identified as a possible cause for amphibian extinction, among others. Ecological niche modeling has proven to be a useful tool to predict potential distribution of species in the context of climatic changes. In this paper, we used the Genetic Algorithm for Rule‐set Prediction (GARP) to model the potential distributions of two species of plethodontid salamanders: Pseudoeurycea cephalica and P. leprosa. We projected their potential distributions under climatic scenarios expected in 50 yr based on a conservative scenario of global climate change and assuming a moderate dispersal ability for both species. Our analyses suggest that climate change effects may pose an additional long‐term risk to both species of plethodontid salamanders, with a more dramatic scenario in the case of P. leprosa. By the year 2050, this species may lose almost 75 percent of its distributional area, and this projection is even worse when deforestation (in the way it is occurring at present) is considered within the predicted model. Our results concur with those obtained for species with limited dispersal capability because they do not track changing climates, but rather face a loss of distributional area. The survival of these species is not secure, even though their potential distributional area falls within a considerable number of natural protected areas.

DISTRIBUTION AND HABITAT OF COLUMBIA TORRENT SALAMANDERS AT MULTIPLE SPATIAL SCALES IN MANAGED FORESTS OF NORTHWESTERN OREGON

Abstract We examined relationships between Columbia torrent salamanders (Rhyacotriton kezeri) and biotic and abiotic habitat attributes at landscape and reach (within-stream) scales in managed forests of northwestern Oregon, USA. In 2000, we found 851 torrent salamanders in 58% of 119 headwater (first-order) streams from randomly selected 2.58-km2 sections of the study area. Landscape-level variation in torrent salamander distribution and relative abundance was related to abiotic landform features that included parent geology, elevation, and aspect, but variation was not related to age or composition of adjacent riparian forests. In 2001, we conducted a more detailed study of salamander occurrence and abundance within 179 10-m stream reaches stratified by geology and gradient. The stream reaches were randomly selected from 40 streams known to contain salamanders. We recorded 1,224 salamanders from 92 (51%) of the stream reaches. Akaike's Information Criterion (AIC) model selection indicated that the globa...

Influence of abundance of small-mammal burrows and conspecifics on the density and distribution of spotted salamanders (Ambystoma maculatum) in terrestrial habitats

Spotted salamander (Ambystoma maculatum) distributions were studied within eighteen 272-m2 field enclosures in upland deciduous forest adjacent to two breeding ponds. The enclosures were subsequently used in experiments involving (i) removal of small-mammal burrows to determine if burrow abundance influenced salamander density and (ii) manipulation of salamander densities to determine if increased density was associated with decreased growth, fecundity, or probability of re-emerging to breed. Mean density of salamanders wintering in enclosures <65 m from the breeding ponds was 1.0/100 m2 (SD = 1.1/100 m2, n = 17, range = 0–4.0/100 m2). Density declined as distance to the nearest breeding pond increased, and the sex ratio was skewed sharply toward males (8:1) wintering close (<65 m) to the pond but not farther from the pond (1:1). Males residing within the enclosures weighed more than males wintering farther from the breeding ponds. Migrating salamanders were over 3 times more likely to leave burrow-removal plots than control plots prior to the summer inactive period. Salamanders housed at high density (15/enclosure) were less likely to re-emerge to breed than were salamanders housed at low density (5/enclosure), but we observed no effects on growth or fecundity. Results suggest that conspecific distribution and burrow availability might affect the density of spotted salamanders within terrestrial habitats.