Number Of Salamanders Research Articles

Local and landscape drivers of the number of individuals and genetic diversity of a microendemic and critically endangered salamander

Conversion of forest ecosystems to human-modified landscapes threatens the persistence of forest-specialist species. However, the local and landscape drivers of population abundance and genetic diversity of these species are largely unknown, especially for elusive and critically endangered species, such as the salamander Pseudoeurycea robertsi—a species microendemic to the Nevado de Toluca volcano, Mexico. We assessed the relative influence of local- and landscape-scale habitat amount and habitat spatial configuration on the number of individuals and genetic diversity of P. robertsi. Given its low vagility, we expected stronger responses to local habitat amount than to landscape variables, with habitat configuration showing the weakest effects on all responses. Using multiscale and multimodel inference approaches, we tested the relative effect of local habitat amount (fallen logs volume), landscape habitat amount (forest cover) and landscape configuration (forest edge density and forest fragmentation per se) on the number of salamanders and its genetic diversity. The number of individuals was more strongly related to local and landscape variables than genetic diversity. As predicted, local habitat amount showed stronger positive effects on number of individuals and number of alleles than forest cover. In addition, all response variables increased in landscapes with lower edge density. Fragmentation per se showed weak influence on all responses. Fallen logs volume is a major driver of this forest-specialist salamander. Yet, edge density also shapes salamander populations, especially the number of individuals. Retaining fallen logs in forests and increasing forest core areas are critical for salamander conservation.

Time of Day Does Not Affect Detection in Visual-Encounter Surveys of a Spring-Dwelling Salamander,Eurycea naufragia

Abstract During 10-weeks, visual-encounter surveys were conducted on the Georgetown salamander Eurycea naufragia at a spring pool in Williamson County, Texas. There was no significant difference in number of salamanders observed or percentage of objects used as cover between surveys in mornings and afternoons. Number of salamanders detected and percentage of objects used as cover were not correlated significantly with any environmental variable that was assessed. These results suggest that visual-encounter surveys conducted during daylight hours are not biased by time of day.

Ovulated female salamander (Hynobius leechii) respond to water currents

To determine whether or not the female Korean salamander, Hynobius leechii , responds to water currents and, if so, whether those responses depend on their reproductive conditions, we evaluated the responses of ovulated and ovipos- ited females to 1-Hz water currents generated by a model salamander with and without the placement of a transpar- ent water current blocker between the model and the test females. The ovulated females responded to water currents by turning their heads toward, approaching, and/or making physical contact with the model. When the water current blocker was in place, the number of salamanders that approached the model was reduced significantly. The approaching and touching responses of ovulated females were greater than those of oviposited females, whereas the other measure- ments evidenced no differences. None of the responses of the oviposited females to water currents was affected by the presence of the blocker. Our results indicate that female H. leechii responds to water currents via a mechanosensory system.

Ecology of Georgetown Salamanders (Eurycea naufragia) Within the Flow of a Spring

Abstract The Georgetown salamander, Eurycea naufragia, is a permanently neotenic salamander known only from about a dozen surface springs and caves in Williamson County, Texas. Rapid urbanization places all known populations at risk and conservation strategies are hindered by a lack of information on the ecology of the species. To better understand requirements of microhabitat and spatial distribution of E. naufragia within flows of surface springs, we conducted counts of salamanders on the surface at one locality over a 12-month period. Numbers of salamanders and percentage of cover objects occupied by salamanders varied among months, with a general trend of higher abundance in spring and summer. Few juveniles were observed, and there was no strong seasonal trend in distribution of size of salamanders. Within the flow of the spring, abundance of salamanders decreased linearly with distance from origin of the spring. Salamanders were more likely to be under rocks than under other types of cover objects an...

The phenology of a rare salamander ( Salamandra infraimmaculata ) in a population breeding under unpredictable ambient conditions: a 25 year study

This is a long-term study (1974-1999) on the phenology of the rare, xeric- inhabiting salamander Salamandra infraimmaculata in a small isolated population during the breeding season near the breeding ponds on Mt. Carmel. This is a fringe area of the genus’ south-easternmost Palaearctic distribution. Salamanders were captured during the 25 year long study. The first years up to the 1980s the total number of salamanders increased but during the last years there seems to have been a decline. Although this could be a phase in normal population cyclic oscillations nevertheless when compared with long-term data on a European Salamandra it does not seem so. The interpretation of the species’ status is dependent on numbers of salamanders captured as well as on the duration of the study. These subjects are reviewed and discussed in this paper.

Stream salamanders as indicators of stream quality in Maryland, USA

Biological indicators are critical to the protection of small, headwater streams and the ecological values they provide. Maryland and other state monitoring programs have determined that fish indicators are ineffective in small streams, where stream salamanders may replace fish as top predators. Because of their life history, physiology, abundance, and ubiquity, stream salamanders are likely representative of biological integrity in these streams. The goal of this study was to determine whether stream salamanders are effective indicators of ecological conditions across biogeographic regions and gradients of human disturbance. During the summers of 2001 and 2002, we intensively surveyed for stream salamanders at 76 stream sites located west of the Maryland Coastal Plain, sites also monitored by the Maryland Biological Stream Survey (MBSS) and City of Gaithersburg. We found 1,584 stream salamanders, including all eight species known in Maryland, using two 15 × 2 m transects and two 4 m2 quadrats that spanned both stream bank and channel. We performed removal sampling on transects to estimate salamander species detection probabilities, which ranged from 0.67-0.85. Stepwise regressions identified 15 of 52 non-salamander variables, representing water quality, physical habitat, land use, and biological conditions, which best predicted salamander metrics. Indicator development involved (1) identifying reference (non-degraded) and degraded sites (using percent forest, shading, riparian buffer width, aesthetic rating, and benthic macroinvertebrate and fish indices of biotic integrity); (2) testing 12 candidate salamander metrics (representing species richness and composition, abundance, species tolerance, and reproductive function) for their ability to distinguish reference from degraded sites; and (3) combining metrics into an index that effectively discriminated sites according to known stream conditions. Final indices for Highlands, Piedmont, and Non-Coastal Plain regions comprised four metrics: number of species, number of salamanders, number of intolerant salamanders, and number of adult salamanders, producing classification efficiencies between 87% and 90%. Partial validation of these indices was obtained when a test of the number of salamanders metric produced an 82% correct classification of 618 MBSS sites surveyed in 1995-97. This study supports the use of stream salamander monitoring and a composite stream salamander index of biotic integrity (SS-IBI) to determine stream quality in Maryland.

Streamside Salamanders in Valley Fill and Reference Streams in Southern West Virginia

We sampled stream salamanders in southern West Virginia during 2001 in streams below head-of-hollow valley fills and in reference streams to determine if there were differing trends in relative abundance between these treatments. Head-of-hollow valley fill construction can cover headwaters, first- order, second-order, and higher order reaches with excess spoil materials; valley fills in southern West Virginia are often hundreds of hectares in size. Total salamander captures were higher in 3 reference streams (RS; N=389) than in 4 valley fill streams (VFS; N=289) and mean abundance was significantly greater in reference streams. Number of salamanders captured was positively related to number of rocks in the stream substrate. We suggest that alterations in water chemistry, substrate composition (greater silt cover), and fewer rocks below valley fills all may have contributed to reduced salamander densities in VFS.

Leaf litterbags: Factors affecting capture of stream-dwelling salamanders

Many standardized techniques are used to monitor terrestrial salamanders, but fewer protocols have been tested for inventorying stream-dwelling salamanders, especially larvae. One new method uses artificial refugia (leaf litterbags) placed in shallow streams. Totest the utility of litterbags, we sampled three transects of 6 litterbags each (2 large, 2 medium, and 2 small) placed in five small, medium, and large streams in Great Smoky Mountains National Park, an area of high aquatic salamander diversity. We captured 690 larval, juvenile, and adult stream-dwelling salamanders of 11 different species from June to November 2000 in the 90 litterbags. Large and medium-sized litterbags were most effective at sampling salamanders in small streams, but all bag sizes worked equally well in medium and large streams. The number of salamanders captured varied seasonally,with most captures in June and July. The depth of bag submergence significantly influenced litterbag use by adult and larval salamanders, but had no effect on juvenile salamanders. Although the technique was effective for determining the presence of many salamander larvae, variation in the numbers of individuals captured and the inability to relate captures to overall abundance make it impossible to monitor trends without considerable additional effort. The ease of deployment and non-destructive methodology suggest that litterbags could be useful in determining salamander presence during inventory programs, especially when the time to sample a large number of sites is limited.

Activity Patterns of Red Hills Salamanders (Phaeognathus hubrichti) at Their Burrow Entrances

The Red Hills salamander (Phaeognathus hubrichti), a large fossorial plethodontid endemic to south-central Alabama, was listed as federally threatened in 1976. To determine the seasonal and daily activity patterns of this species, I counted the number of salamanders present at burrow entrances, recorded the amount of time individual salamanders spent at entrances, and measured five abiotic variables to determine how they correlated with the number of salamanders at burrow entrances. Red Hills salamanders were present at burrow entrances all months of the year, displayed a unimodal daily activity pattern, and spent a mean of 12.3 continuous hours at an entrance each day. Regardless of season, time spent at an entrance remained relatively constant. Air temperature had the highest correlation with the number of salamanders present at entrances. Burrow entrances play a prominent role in the lives of these salamanders. When estimating population size for conservation efforts, surveys should be conducted at night and at multiple times and dates during the warmer months of the year because not all salamanders are present at entrances at any one time.

Disappearance and Return of Plethodontid Salamanders to Clearcut Plots in the Southern Blue Ridge Mountains

The disappearance and return of plethodontid salamanders on clearcuts has been monitored since 1979 in the southern Blue Ridge Mountains at three sites near Highlands, North Carolina. Salamander abundance on 225 m2 plots located on clearcuts and in nearby forest was determined by nightly non‐destructive searches. Abundances on clearcut and forest plots at a given site were compared for each year in which sampling occurred. Numbers of salamanders on clearcut plots decreased to 30–50% of forested plots in the first year after logging and were almost zero by the second year. Decreases in standing crop and moisture content of leaf litter seem responsible for salamander disappearance. Salamanders returned to clearcuts 4–6 years after cutting, and their numbers increased rapidly. Linear regressions estimate that salamander numbers on clearcut plots will equal or exceed numbers on forested plots by 20–24 years after cutting. The pattern of salamander return to clearcuts appears closely correlated with the timing of litter layer reformation. All sex and age classes of the most common species, Plethodon jordani, disappear from clearcuts at equal rates, whereas the earliest colonizers are predominantly large adults. Plethodon oconaluftee, a desiccation‐resistant species, exists on regenerating clearcuts in disproportionately large numbers. Large adults of all species, including Plethodon oconaluftee, may be better able to withstand the drier, sparse litter cover of young, regenerating stands. Adults might move to clearcuts to avoid competition from smaller and immature salamanders restricted to mature forests with abundant, moist litter.

Experimental studies on direct and indirect interactions in a three trophic-level stream system.

We used a complete block design to experimentally study direct and indirect interactions in a three trophic-level freshwater system consisting of a top predator, the green sunfish, Lepomis cyanellus, an intermediate predator, small-mouthed salamander larvae, Ambystoma barbouri, and prey, hatchling isopods, Lirceus fontinalis. This system occurs naturally in small stream pools in central Kentucky; experiments were done in laboratory pools. Salamander larvae ate isopods and thus had a direct, negative effect on isopod survival. Accordingly, isopods responded to the presence of salamander larvae by increasing their tendency to bury themselves in the sand substrate. Fish ate salamanders and thus had a direct, negative effect on salamander survival. Salamanders responded to fish presence by increasing their time spent under plexiglass plates that simulate refuge rocks. The overall effect of fish on isopods depended on the presence of salamanders. In the absence of salamanders, fish predation on isopods had a direct, negative effect on isopod survival; isopods thus responded to the presence of fish by burying themselves in the sand. With salamanders present, fish had a positive overall effect on isopod survival; i.e., direct, negative effects of fish on isopods were outweighed by indirect, positive effects. Indirect positive effects of fish on isopods came through a reduction in salamander predation rates on isopods in the presence of fish. The mechanism involved both a decrease in the number of salamanders (a trophic-linkage indirect effect; cf. Miller and Kerfoot 1987) and a reduction in the feeding rate of individual salamanders on isopods (a behavioral indirect effect). The decrease in individual salamander feeding rates on isopods was due to reductions in both salamander activity and in spatial overlap between salamanders and isopods in the presence of fish. The latter effect reflected the fact that salamanders and isopods used different refuges from fish; salamanders went under refuge plates, whereas isopods primarily buried themselves in sand. Estimates of the relative importance of various direct and indirect effects of sunfish on isopods suggested that positive, behavioral indirect effects were of roughly the same magnitude as direct, negative effects, both of which were more important than were trophic-linkage indirect effects. Contrary to expectations, the presence of isopods did not affect the refuge use or survival of salamanders in the presence of fish.

The abundance of salamanders in forest stands with different histories of disturbance

Because of the importance of salamanders in forest food chains, the effects of forest management practices on populations of these animals warrant consideration. We compared the numbers and activity patterns of salamanders in areas of a deciduous forest in central New York State that had been cut selectively for firewood, or clearcut, or planted with conifers. Numbers of salamanders were lower in three recently distrurbed habitats than in adjacent old-growth control stands. The frequency of above-ground activity by both species of salamanders was positively correlated with the density of understory vegetation and the depth of leaf litter. Small-scale habitat disruption associated with harvesting firewood increased the numbers of the terrestrial eft stage of the red-spotted newt ( Notophthalmus viridescens) but had no effect on numbers of red-backed salamanders ( Plethodon cinereus). A recently clearcut area had fewer red-backed salamanders than adjacent old-growth forest had, but the numbers of salamanders in a 60-year-old second-growth forest were indistinguishable from those in the adjacent old-growth forest. Populations of salamanders in a conifer plantation were low. Thus, salamanders seem to be resilient to limited disturbance of forests, but major changes are likely to affect populations of salamanders and, consequently, of birds and mammals that depend on salamanders for food.

The Effects of Variation in Streamside Habitats on the Composition of Mountain Salamander Communities

this salamander community. The semi-aquatic Desmognathus monticola was found farther from water in streams with the larger semi-aquatic D. quadramaculatus than in streams without it. At a densely populated site, streambank burrows were monopolized by large desmognathines. These burrows were regularly spaced as expected if equal-sized desmognathines avoid occupied burrows. The addition of rocky or woody streambank cover to small streams increased the numbers of salamanders found in

Unmodifiability of Locomotor Coordination in Amphibia, Demonstrated by the Reverse Functioning of Mutually Exchanged Right and Left Limbs

According to the so-called resonance principle, a spinal limb center produces motor impulses specific for each individual muscle, to which the motor nerves, specified appropriately by their muscles, respond selectively. A reflex pattern is an orderly timed (coordinated) sequence of such specific impulses. Left and right half of a spinal center act separately. Corresponding left and right muscles are of identical specificity. A supernumerary muscle, through its specified nerve, picks up the messages emitted for the normal muscle of the same name in the district; therefore, a supernumerary limb grafted into the district of a normal limb acts always simultaneously and identically with the latter. If the supernumerary and the nearby normal limb are of opposite laterality (e. g., a right leg grafted near a left leg), their movements are mirror images of each other, and if the supernumerary limb can reach the ground, its movements necessarily counteract the effects of the normal limb. The animals never “learn” to remedy this impediment, at least not in the cases where the normal limb remains functional. There the question arose as to whether, if the normal limbs were removed and limbs of opposite laterality were grafted in their places, the function of the latter would still be reversed as it is in the presence of the normal limbs, or whether some adjustment in the emission pattern of the reflex might not make the grafts serviceable to the body. In a number of salamanders (Amblystoma punctatum larv.), fully developed right and left fore limbs, including the shoulder girdles, were exchanged by dorso-dorsal transplantation, i. e., palms down-ward and fore arms pointing caudad. After reinnervation had taken place, the grafts moved in perfect coordination, but always in exactly the reverse sense from what the animal obviously intended.

A Structural Feature Connected with the Mating of Diemyctylus viridescens

THERE seems to be very little doubt at present that the fertilization of Urodela is internal. Since Spallanzi in I785 proved internal fertilization must take place with Triton, many investigators have shown conclusively that such is the case in other species. The mating habits of a number of salamanders have been observed, but very much is yet to be learned about many forms concerning which we now know little more than the mere fact that fertilization is internal ; however, it seems very probable that in all Urodela fertilization is accomplished by a similar method. In most cases the courtship is more or less complicated and terminates with the female following the male, who emits a spermatophore containing zobsperms, which is received by the cloaca of the female as she passes over it. There are many variations in the mating habits of different forms described, but unfortunately few species are easy to observe. Of American forms practically nothing is known of the more terrestrial species. Dieiyctylus v'I zdcsccOns and D. lorosits of the aquatic species are about the only ones in which a satisfactory idea of the matinghas been obtained. A number of observations have been made upon European salamanders by Robin ('74), Gasco ('80), and Ze]ler ('90), who have given good accounts of their habits. With Triton, for instance, Zeller has carefully described the antics of the male before the female ; these may extend over a period of hours; he rubs against her and rushes before her. At length she is attracted by him, and as he moves off she follows and receives 643