We examined how variation in food availability and temperature influences patterns of energy allocation to growth, storage, metamorphosis, and reproduction in larval Ambystoma maculatum and A. tigrinum. In each species, an allocation vector consisting of metamorphic size, duration of larval period, fat body mass, and gonad mass was influenced by both food and temperature. Larvae grew rapidly at high food levels and high temperature, and delayed metamorphosis when grown at low temperature. High food levels resulted in larger fat bodies and decreased time to metamorphosis in A. tigrinum, and larger gonads in both species. The allocation vector collectively representing growth rate, storage, reproduction and metamorphosis differed between species: in A. maculatum, only the correlation between metamorphic size and fat body mass was significant, whereas all four variables were influenced in A. tigrinum. An interaction of food and temperature on the allocation vector was only detected for A. tigrinum. Our results indicate that interaction among allocation variables is stronger in some species than others and that these associations might be important in understanding life history variation between these species.

Spatial capture–recapture (SCR) is a relatively recent development in ecological statistics that provides a spatial context for estimating abundance and space use patterns, and improves inference about absolute population density. SCR has been applied to individual encounter data collected noninvasively using methods such as camera traps, hair snares, and scat surveys. Despite the widespread use of capture-based surveys to monitor amphibians and reptiles, there are few applications of SCR in the herpetological literature. We demonstrate the utility of the application of SCR for studies of reptiles and amphibians by analyzing capture–recapture data from Red-Backed Salamanders, Plethodon cinereus, collected using artificial cover boards. Using SCR to analyze spatial encounter histories of marked individuals, we found evidence that density differed little among four sites within the same forest (on average, 1.59 salamanders/m²) and that salamander detection probability peaked in early October (Julian day 278) reflecting expected surface activity patterns of the species. The spatial scale of detectability, a measure of space use, indicates that the home range size for this population of Red-Backed Salamanders in autumn was 16.89 m². Surveying reptiles and amphibians using artificial cover boards regularly generates spatial encounter history data of known individuals, which can readily be analyzed using SCR methods, providing estimates of absolute density and inference about the spatial scale of habitat use.

Natural history and behavioral information for species of the genus Pristimantis is scarce. We conducted an extensive study of Pristimantis eremitus, a vulnerable species for which there is scant biological information. We monitored 17 individuals for movements and intraspecific interactions for 13 mo. We describe the species’ variation in dorsal color and pattern, which we used to uniquely identify individuals during the study. We also present results on the habitat utilization and home range of this species, providing evidence that this species shows a preference toward the bromeliad microhabitat when compared with other microhabitat types. We also describe the advertisement call and associated behaviors of the species. We update the known distribution of the species. Our data provide a baseline for future researchers to survey and identify individuals of P. eremitus, and which could be applied comparatively to other species where little of their natural history is known. We also show how an in-depth in situ study can provide useful information for species conservation.

Climate change is considered a serious threat to biodiversity. If populations no longer have physiological, morphological, or behavioral adaptations to withstand novel climatic conditions, or if they are unable to change the timing of crucial life-history events to avoid the months with unfavorable climates, the only alternative might be to track appropriate conditions in space and follow them. This study explores the latter scenario and evaluates the potential spatial effects that climate change might exert on four wide-ranging generalist anurans from South America. Using six methods to model ecological niches and different climate change scenarios for 2050, we found that these treefrog species are predicted to experience a contraction in their geographical ranges at magnitudes varying from 13.90% (Dendropsophus nanus) to 52.06% (D. minutus) because of the loss of climatically suitable areas. These areas are mainly located in the northern perimeter of the current species distribution. Conversely, only minor gains in new climatically suitable areas are predicted for these species (except for D. minutus). Finally, all species are predicted to be found almost exclusively within the Brazilian Atlantic Forest and to be absent from the lowlands of the Pantanal floodplains by 2050.

Jumping is one of the most common modes of locomotion for animals, and animals in the wild often jump off a range of substrates. We tested the effects of varying surface diameter (1 and 5 cm) on jumping performance and kinematics in two species of arboreal geckos (Rhacodactylus auriculatus and Correlophus ciliatus). Both are medium-sized (~10–15 g) geckos that readily jump off a range of diameters. We filmed maximal jumps with a Photron high-speed camera at 500 frames · s⁻¹. We found that diameter had little impact on either jumping performance (distance) or kinematics (takeoff angle and speed, landing angle, jump duration), but mass had a positive effect on both jump distance and takeoff speed in C. ciliatus. Further, C. ciliatus exhibited higher takeoff velocities and tended to have greater jump distances compared to R. auriculatus. The factors causing this among-species difference are unclear, but differences in both tail morphology and how these species use their tails could partly explain this difference. Our study confirms other studies, which show that lizards are scarcely affected by diameter in terms of jumping, and we discuss some of the reasons for why lizards are able to effectively overcome this environmental challenge.

The conspicuous colors found in many lizards transfer information about their owner’s characteristics that are relevant to mating and social systems. Female European Green Lizards (Lacerta viridis) have been shown to prefer males with high ultraviolet (UV) throat reflectance. Additionally, components of throat patch color (such as UV chroma and brightness) have been shown to be condition-dependent and to signal relative head size and health status. In this study, we investigated whether or not different components of male nuptial color and other relevant traits were associated with characteristics of male space use during the reproductive season at two different locations. In Site 1, lizard density was two times higher, territory size was one third as large, and spatial overlap between territories was about half as large as in Site 2. Males at Site 1 showed movement patterns consistent with a mix of territorial and floater individuals, with floaters exhibiting greater throat brightness. Those males at Site 2 moved in a less predictable manner within the study plot, irrespective of their nuptial color. Among territorial males, those of larger head size occupied larger territories but maintained lower brightness and blue chroma. Our results indicate that (1) not all males are territorial; (2) being territorial might have a cost expressed in duller nuptial color; (3) components of nuptial color can signal territory size; and (4) the information content of a multiple signaling system may vary between populations according to the mating system structure present.

Discriminating between conspecific and heterospecific communication signals has important implications for evolution. The benefits of such discriminations are clear for sympatric congeners, but if conspecific display recognition (CDR) has a cost, it should be relaxed in species that have evolved in isolation. Of the nine lava lizard species (Microlophus spp.) endemic to the Galápagos Islands, all are thought to have evolved in allopatry and none overlap in geographic distribution. Although prior research failed to reveal CDR in male M. grayii on Floreana Island, male M. indefatigabilis on Santa Cruz Island showed a response bias toward conspecific displays under the same experimental conditions. In the present study we tested for CDR in two additional species: M. albemarlensis on Isabella Island and M. bivittatus on San Cristóbal Island. Subjects were presented with computer-controlled robots that either performed the conspecific display, a reversed-inverted conspecific display, or a display from an Anolis lizard species. Results revealed evidence of CDR in male M. albemarlensis, but no such evidence in male M. bivittatus. Interestingly, bathymetric data provide a potential explanation for CDR in M. indefatigabilis and M. albemarlensis: a land bridge between Santa Cruz and Isabella might have resulted in secondary contact and reinforcement in these two species during Pleistocene glacial maxima. Another possibility is that intraspecific selection for discrimination among males has caused heterospecific displays to be viewed as low-fidelity conspecific displays. Nevertheless, our findings are consistent with CDR being lost early in Galápagos Microlophus evolution, as predicted for allopatric speciation, and re-emerging later only where selection favored the discrimination of male displays.

Foraging is a key aspect of a species’ ecology and decisions made while foraging affect fitness in many ways. Although much research has focused on snake foraging, only a handful of detailed studies have been conducted on free-ranging individuals, all on Crotalus horridus. We used fixed videography to collect data on free-ranging Northern Pacific Rattlesnake (Crotalus oreganus) behavior to qualitatively test predictions regarding interspecific differences in rattlesnake foraging behavior. We analyzed foraging behaviors based on encounter rates with prey and strike rates on prey, distances moved between consecutive ambush sites, residency time at each site, and poststrike behaviors. Snakes encountered approximately 4 prey/d, with California Ground Squirrels (Otospermophilus beecheyi) being encountered at much higher rates than other prey types. Crotalus oreganus typically did not remain at hunting sites for long durations compared with other species, and generally exhibited short distance movements (<10 m) to new sites. Snakes initiated strikes during 21% of all prey encounters, and 49% of these strikes were successful. Snakes were more likely to hold on to nonsquirrel prey than squirrels after a strike. When snakes struck and released prey, the distance prey fled after a strike was positively related to the time snakes spent locating the envenomated prey. Our findings indicate that variation in rattlesnake foraging behavior both within and between species might be driven largely by differences in habitat features, including prey abundance.

An animal’s decision to stay in a protective refuge or venture from it will depend on the exigencies of other necessary functions (e.g., feeding, breeding, thermoregulation), which often will interact themselves. In this study, we determined broad patterns of use of cover objects in five species of diurnal natricine snakes at two locations in Canada and one location in the UK. In particular, we focused on the influence of body size (larger snakes should incur less risk away from cover) and reproductive state (gravid snakes thermoregulate precisely and therefore should often bask) on the probability that a snake will be found in the open. As we predicted, body size influenced the likelihood of being in the open, both within and between species (one small species was almost always found under cover), even when we took time of day, season, or both into account. Such relationships are unlikely to be solely caused by the thermoregulatory role of cover, and we argue that small snakes sometimes sacrifice basking opportunities to take advantage of the protective qualities of cover. However, small snakes might use cover to avoid dehydration as well as predators. As we also predicted, gravid females were more likely to be in the open at a given body size than other snakes, but only in the three largest viviparous species; the smallest species and one oviparous species showed no such effect. In general, body size and reproductive state both determine cover-use behavior. Studies of use of other kinds of cover or refuges by snakes (e.g., vegetation, underground burrows), and of time spent under cover vs. in the open, would help test the generality of our conclusions.

The dipsadid snake genus Tropidodryas consists of two species that occur in the Atlantic Forest along Brazil’s eastern coast, a conservation hot spot. Life-history information on pairs of sister species might allow insights into the evolutionary transitions that have occurred since the cladogenesis that putatively gave rise to them. We provide information on distribution, morphology, diet, reproduction, and seasonal activity of these species based on the examination of 624 specimens. The genus Tropidodryas occurs along a large extent of the Atlantic Forest of eastern Brazil, with T. striaticeps occurring at higher elevations, on average, than T. serra. These snakes forage by day either on the ground or in vegetation, consuming a wide variety of vertebrates, mainly mammals. Higher proportions of birds in the diet of T. serra and certain mammals in the diet of T. striaticeps probably reflect elevational differences in prey availability. An ontogenetic diet shift occurs in both species, with juveniles consuming mainly ectothermic prey (lizards and anurans), and adults preying predominantly on mammals. Caudal luring has been documented in juveniles, but the pale color and high frequency of injuries on the tail of larger individuals indicate that adult T. striaticeps also employ this technique to attract prey. Sexual dimorphism occurs in body size, tail size, and diameter of the eye. Female reproductive cycles are seasonal in both species, with egg laying occurring in warmer periods of the year. However, T. striaticeps seems to have a more extended reproductive cycle, with some females being able to lay eggs 1 or 2 mo earlier. Environmental differences between high and low altitudes in the Atlantic Forest are likely responsible for the slight ecological divergence between these two closely related snakes.