Showing papers in "Journal of Herpetology in 2005"
TL;DR: Clearcutting and other forest management practices that remove canopy and disturb ground cover may exacerbate the risk of desiccation, particularly for newly metamorphosed amphibians, and results demonstrate that this risk is strongly mediated by the availability of burrows.
Abstract: Clearcutting and other forest management practices that remove canopy and disturb ground cover may exacerbate the risk of desiccation, particularly for newly metamorphosed amphibians. We exam- ined dehydration rates of juvenile Mole Salamanders (Ambystoma talpoideum) in relation to burrow avail- ability in four experimental forest management treatments. Juvenile salamanders (N 5 41) were confined to small enclosures in four treatments representing a range of habitat disturbance: clearcut with coarse woody debris (CWD) removed; clearcut with CWD retained; thinning; and an unharvested control of second-growth, mature loblolly pine. Half of the salamanders in each habitat treatment were provided with artificial burrows. Water loss over 72 h was significantly higher in the clearcut with CWD retained than in the other three treatments. Most water loss occurred during the first two nights, when salamanders may have been most active. Only 40% of salamanders without burrows survived in the clearcuts, versus 90% in the thinned stand and 100% in the control. Ninety percent of the salamanders with access to a burrow survived in the clearcuts versus 100% in the thinning and control. We found no correlation between soil moisture and water loss and attribute higher desiccation rates in the clearcuts to high temperatures (> 448C). Although habitat changes resulting from thinning did not lead to increased desiccation, complete canopy removal greatly increased risk of mortality caused by desiccation. Our results also demonstrate that this risk is strongly mediated by the availability of burrows.
112 citations
TL;DR: It is hypothesized that, in at least some species, males compete for calling sites in areas with high female density and with favorable sound transmission features, and little support is found for the hypothesis that dendrobatids exhibit resource defense polygyny.
Abstract: One or both sexes exhibit territorial behavior in all dendrobatids that have been studied. Two types of territoriality are identified. In some Colosthethus species only females or both sexes defend small nonreproductive territories that offer access to water, food, and shelter. In other species, only males defend large reproductive territories against conspecific calling males, suggesting that females are the limited resource. However, in no case has the defended resource been unambiguously identified. I hypothesize that, in at least some species, males compete for calling sites in areas with high female density and with favorable sound transmission features. I found little support for the hypothesis that dendrobatids exhibit resource defense polygyny. More research is necessary to understand the function of territoriality and to identify limiting resources in poison frogs.
102 citations
TL;DR: It is concluded that unpalatability is rare, but when it occurs, it is a property of an ensemble (predator, prey, and alternative prey) and a life-history stage in a particular circumstance but is not a species-specific attribute.
Abstract: We examined 142 papers, which contained 603 separate predator-prey trials, to investigate whether unpalatability is an important defense against predation for amphibian eggs and larvae. Although unpalatability is often cited as an antipredator defense, it was rarely demonstrated that 89% of the trials that we reviewed found prey to be palatable. The most extensively studied taxa, the genera Bufo and Rana, were diagnosed unpalatable at rates comparable to all other taxa. Diagnoses of unpalatability were not always consistent for a prey species across different predators and were influenced by experimental method. Despite these limitations and our conservative definition of unpalatability, several patterns emerged. First, across all taxonomic groups, eggs and hatchlings were unpalatable more often than mobile larval stages. Second, species that breed in temporary ponds were more likely to be palatable to fish predators than those that breed in permanent habitats. Third, fish and caudates were more likely to find amphibian prey unpalatable than insect predators. We conclude that unpalatability is rare, but when it occurs, it is a property of an ensemble (predator, prey, and alternative prey) and a life-history stage in a particular circumstance but is not a species- specific attribute. We suggest methods of experimentation that could strengthen future research on the palatability of amphibian eggs and larvae.
102 citations
TL;DR: In this study, anurans were able to offset small size at metamorphosis with terrestrial growth, although there was a trend of reduced overwinter survival for ranid species that metamorphosed at a smaller size.
Abstract: I reared four species of anurans (Rana sphenocephala [Southern Leopard Frog], Rana blairi [Plains Leopard Frog], Rana clamitans [Green Frog], and Bufo woodhousii [Woodhouse's Toad]) for seven to 12 months in small, outdoor terrestrial enclosures (1 × 2 m) to examine the consequences of larval competition (via density) and contaminant exposure (via the insecticide carbaryl). I added six Rana clamitans, eight Rana sphenocephala, eight Rana blairi, and 10 Bufo woodhousii to terrestrial enclosures shortly after metamorphosis and recaptured them during the following spring. All anurans from low-density ponds were significantly larger than those from high-density ponds, but these size differences did not significantly affect survival to or size at spring emergence. However, R. sphenocephala, R. blairi, and R. clamitans that survived to spring had been larger at metamorphosis on average than those that did not survive; in contrast, B. woodhousii that survived the winter were smaller at metamorphosis on ...
93 citations
TL;DR: Raccoons seemed to locate terrapin nests based on soil disturbance, ocean-water scent, or a combination of these cues, and marking nests with flags and human scent decreased predation rates.
Abstract: We simulated nests constructed in an area heavily used by ovipositing Diamond-backed Terrapins (Malaclemys terrapin) and foraging raccoons (Procyon lotor), to investigate the cues used by raccoons to locate terrapin nests. Marking nests with flags did not increase predation rates, and human scent decreased predation rates. Raccoons seemed to locate nests based on soil disturbance, ocean-water scent, or a combination of these cues.
81 citations
TL;DR: Diet of introduced Bullfrogs and three native frog species co-occurring at a group of ponds on Daishan Island is examined to gain insight into the nature of potential interactions between Bull Frogs and native frogs, suggesting that female Bull frogs may threaten native frogs by both competition and predation.
Abstract: We examined diet of introduced Bullfrogs (Rana catesbeiana) and three native frog species (Rana limnocharis, Rana nigromaculata, and Bufo bufo gargarizans) co-occurring at a group of ponds on Daishan Island, east of China, to gain insight into the nature of potential interactions between Bullfrogs and native frog species. For postmetamorphic Bullfrogs, aquatic prey items dominated volumetrically. Prey size, diet volume and volumetric percentage of native frogs in diet increased with Bullfrog body size. The number and volumetric percentage of native frogs in the diet were not different for female and male Bullfrogs, and both were higher for adults than for juveniles. Diet overlap between males and juveniles was higher than that between males and females and between females and juveniles. Diet overlap with each native frog species of male Bullfrogs was lower than that of female Bullfrogs and juvenile Bullfrogs. We did not exam effects of Bullfrogs on native frogs but our results suggest that the primary threat posed by juvenile Bullfrogs to native frogs on Daishan Island is competition for food, whereas the primary threat posed by male Bullfrogs is direct predation. Female Bullfrogs may threaten native frogs by both competition and predation. These differences among Bullfrog groups may be attributed to differences in body size and microhabitat use.
80 citations
TL;DR: Increased predation at the end of the nestling period suggests that avian activity (i.e., feeding visits, nest defense, and nestling movement) contributes to the foraging success of snakes at the authors' sites.
Abstract: Snakes are frequent predators of eggs and nestlings, but general patterns of snake predation at bird nests are not well known. We reviewed 84 video observations of snakes visiting nests of four songbird species in Texas and Missouri to identify patterns of predatory behavior. Eastern Ratsnakes (Elaphe obsoleta) were the most common species, and coachwhips, racers, kingsnakes, and a garter snake also were recorded. Snakes almost always removed all nest contents during a single visit but sometimes force-fledged nestlings that were old enough to escape. During many visits late in the nestling period, snakes pinned their prey in the nest while feeding, thereby preventing many of the young from escaping. Snakes spent an average of 13 min and 23 sec at each nest (1 min and 52 sec before striking), and the duration of nocturnal visits exceeded the duration of diurnal visits. Snakes sometimes returned to empty nests after they caused failure but only after nestlings were depredated. Visits by Texas Ratsnakes (Elaphe obsoleta lindheimeri) were mostly nocturnal, whereas visits by Black Ratsnakes (Elaphe obsoleta obsoleta), coachwhips, racers, and kingsnakes were diurnal. Snake predation increased as the nesting cycle progressed with the highest rate occurring in the last few days of the nestling period. Increased predation at the end of the nestling period suggests that avian activity (i.e., feeding visits, nest defense, and nestling movement) contributes to the foraging success of snakes at our sites.
73 citations
TL;DR: Kernel estimators were more effective at representing uneven home range use, often demonstrating the extensive use of water in box turtles, and should be considered in wetland area conservation decisions where appropriate.
Abstract: The literature on Eastern Box Turtles (Terrapene carolina carolina: Emydidae) often characterizes them as terrestrial with only anecdotal references to their aquatic habits. The rapid decline in many populations of box turtles suggests an urgent need to assess all aspects of their habitat requirements. In this study, trailing devices and radio transmitters were used to determine seasonal movements and the extent to which turtles used aquatic habitats within their home ranges. Home range sizes averaged 1.88 ± 0.49 ha via minimum convex polygon analysis, and 2.26 ± 0.76 ha via 95% fixed kernel analysis. Kernel estimators were more effective at representing uneven home range use, often demonstrating the extensive use of water. A total of 131 turtles were found in two small temporary ponds from June through August. Individuals remained in the ponds for up to 23 consecutive days. As many as 32 turtles were found at one time in one of these ponds. Turtles often extended their home ranges by means of ab...
63 citations
TL;DR: Four distinct vocalizations emitted by adult males of Scinax fuscomarginatus are described, including the advertisement call, which is novel and promotes attraction of new individuals to the chorus.
Abstract: Vocalizations are important in anuran communication, especially during the breeding season. Calling affects spatial organization of males at breeding sites, promotes attraction of new individuals to the chorus, and attracts mature females for reproduction. We describe four distinct vocalizations (advertisement calls, sporadic calls, and two types of aggressive calls) emitted by adult males of Scinax fuscomarginatus. With the exception of the advertisement call, the remaining descriptions are novel. We also describe calling sites, calling season, and nightly calling activity. Fieldwork was made in a fragment of Cerrado (Estacao Ecologica de Itirapina), Municipalities of Itirapina and Brotas, State of Sao Paulo, southeastern Brazil. At this ecological station, S. fuscomarginatus exhibits a complex acoustic repertoire, social interactions and a prolonged reproductive pattern similar to observations of congeneric species at other localities.
63 citations
TL;DR: It is suggested that researchers should be cautious before applying toe-clipping as a marking technique to pad-bearing lizards because it may affect clinging ability because of the severing of a tendon that plays a key role in toepad function.
Abstract: Toe-clipping is a simple and widely used method for permanently marking small lizards. Although some studies have shown negligible effects of toe-clipping on locomotor performance and survival in terrestrial lizards, less is known about effects of toe-clipping on arboreal lizards. We evaluated effects of toe-clipping on clinging performance of the small arboreal, pad-bearing lizard Anolis carolinensis. We also examined how clinging ability scaled with size within this species. We measured clinging ability in the same lizards with unclipped toes and with one (two toes clipped total) and two toes (four toes clipped total) clipped per each forelimb. We found that clinging ability decreased dramatically even after clipping only two toes (about a 40% decline) and even more dramatically after clipping four toes (about a 60% decline). We also found that clinging ability scales isometrically with body size within unclipped anoles. Because clinging ability was measured on a smooth substrate and was not in...
61 citations
TL;DR: Either hind-limb plasticity is widespread within the genus Anolis or that it has evolved independently at least twice, as suggested by the finding that hatchlings exposed to only broad substrates developed relatively longer hind limbs for their body size compared to hatchlings expose to only narrow substrates.
Abstract: The positive relationship between hind-limb length and perch diameter is well established in Anolis lizards, both among populations of some species and among species. Interspecific comparisons indicate that longer legs confer an advantage for increased running speed on broad substrates, whereas shorter limbs provide greater maneuverability on narrow surfaces. In this light, phenotypic plasticity for hind-limb length previously detected in Anolis sagrei may be adaptive because hatchlings exposed to only broad substrates developed relatively longer hind limbs for their body size compared to hatchlings exposed to only narrow substrates. We tested the generality of hind-limb length plasticity in Anolis by conducting a hatchling growth experiment on Anolis carolinensis, a distant relative of A. sagrei and a different type of habitat specialist. Similar to A. sagrei, A. carolinensis grown in cages with different sized perches showed hind-limb length plasticity, but the magnitude of difference between treatments and sexes was less for A. carolinensis than for A. sagrei. This finding suggests either hind-limb plasticity is widespread within the genus Anolis or that it has evolved independently at least twice.
TL;DR: The evidence suggests that the evolution of head width differences is driven by male contest competition in P. garrulus, which produces very large offspring and thereby invest heavily in a single offspring.
Abstract: We examined museum specimens of the Common Barking Gecko (Ptenopus garrulus) from the Kalahari and Namib Deserts to assess sexual size dimorphism, reproductive status, and diet. Males had significantly wider heads than females of the same body size; however, P. garrulus showed no sexual dimorphism in any other morphological character. The smallest mature male was 36 mm snout-vent length, whereas the smallest female was 31 mm. Peak reproductive activity for both sexes was in September and October. Clutch size was fixed at one large egg (average size 5 5.9 3 4.4 mm); all eggs were in the right ovary, but more than one clutch may be laid in a single breeding season. Ptenopus garrulus, when compared with other geckos, produces very large offspring and thereby invest heavily in a single offspring. We recorded 15 arthropod orders in the diet of P. garrulus. Termites dominated their diet both numerically and volumetrically. Males and females ate prey of similar taxa and sizes, suggesting that trophic partitioning is absent. Therefore, the evidence suggests that the evolution of head width differences is driven by male contest competition.
TL;DR: The increasing frequency of occurrence, extensive distribution, and size diversity of B. constrictor indicate that a large, reproductively successful population is established on Aruba, and there is concern about the potential impact of this invasive predator on the Aruban fauna.
Abstract: Boa constrictor was first documented on the island of Aruba in April of 1999. By the end of December, 2003, 273 B. constrictor had been captured. These snakes ranged in size from neonates (0.30 m total length) to large adults (2.8 m total length) and included at least two gravid females. Boa constrictor is currently distributed islandwide with the highest frequency of occurrence in the southern and southeastern portions of the island. The increasing frequency of occurrence, extensive distribution, and size diversity of B. constrictor indicate that a large, reproductively successful population is established on Aruba. The diet of the B. constrictor on Aruba was determined from the examination of stomach content and scat samples (N = 47). Birds comprised 40.4%, lizards 34.6% and mammals 25.0% of 52 separate prey items identified. A correlation was found between snake total length and prey mass (r(28) = 0.49, P < 0.01) suggesting an ontogenetic shift in the diet at a total length of approximately 1....
TL;DR: Individual variability in movement is more the rule than the exception and common seasonal patterns in movement and space use do exist and home-range sizes vary through time yet remain in the same general location.
Abstract: We studied the movement ecology of Coastal Rosy Boas (Lichanura roseofusca) by radio tracking 17 animals across four sites for up to four years. The typical movement pattern included many short distance moves with rare long distance movements. These skewed distributions made the mean a poor descriptor of movement and this is likely a common issue in other studies. Sexes had similar movement patterns and moved less frequently and shorter distances per day during cooler seasons. Rare long-distance movements occurred primarily in the spring. Propensity to move and mean distance moved per day varied across sites. Home-range size increased with additional fixes even after four years and had a seasonal pattern, increasing during warmer seasons and remaining stable or shrinking during cooler seasons. Despite using novel habitat in sequential years, nearly all individuals used the same general area over longer periods of time. Finally, individuals of both sexes had high levels of spatial overlap. The results indicate for L. roseofusca (1) Individual variability in movement is more the rule than the exception; (2) Common seasonal patterns in movement and space use do exist; (3) Home-range sizes vary through time yet remain in the same general location; and (4) A lack of territoriality and considerable overlap in space use exist.
TL;DR: This is the third species of amphiban or reptile restricted to the southern portion of the Malay Peninsula and differs from all other Cyrtodactylus by having a unique suite of characteristics involving coloration and scalation.
Abstract: A new species of Cyrtodactylus is described from lowland forest of southern Peninsular Malaysia. It differs from all other Cyrtodactylus by having a unique suite of characteristics involving coloration and scalation. This is the third species of amphiban or reptile restricted to the southern portion of the Malay Peninsula.
TL;DR: The relationship between rainfall on the date of oviposition and depredation of nests of the Painted Turtle, Chrysemys picta, on a major nesting beach between 1996 and 2003 was studied.
Abstract: It is commonly thought that predators use olfactory cues to find turtle nests and that these cues are diminished by rainfall. We studied the relationship between rainfall on the date of oviposition and depredation of nests of the Painted Turtle, Chrysemys picta, on a major nesting beach between 1996 and 2003. We analyzed two scenarios: rainfall versus no rainfall on the date of oviposition; and no rainfall versus intense or weak rainfall on the date of oviposition. For the first scenario, we found no consistent association between rainfall and nest depredation before hatching. In 1996, rainfall on the date of oviposition appeared to increase the chance of nest depredation; in 2000, it appeared to decrease the chance of nest depredation; and there was no statistically significant relationship in the remaining years or overall. In the second analysis, the relative amount of rain was associated with nest depredation before hatching. Nests constructed on days with a larger amount of rain were less likely to be depredated than nests constructed on days with no rain or smaller amounts of rain. Nests constructed on days with smaller amounts of rain were more likely to be depredated than nests constructed on days with no rain.
TL;DR: During two reproductive seasons in a Cerrado remnant in southeastern Brazil, this low-cost device did not appear to interfere with the activities of the frogs and allowed for constant monitoring, showing precise routes of movement and great predictability of relocations.
Abstract: Capture/recapture studies significantly increase our knowledge of the natural history of anuran amphibians. Many different methods have been employed in these studies, but a number of new techniques still require experimental validation. During two reproductive seasons in a Cerrado remnant in southeastern Brazil, we investigated the movement patterns and habitat use of the pepper frog, Leptodactylus labyrinthicus, using a spool-and-line device. This low-cost device did not appear to interfere with the activities of the frogs and allowed for constant monitoring, showing precise routes of movement and great predictability of relocations. Both sexes were active at night. During the day, males and females made use of retreat sites under vegetation or in burrows constructed by small- and medium-sized mammals. Males and females did not use standardized routes; there were no significant differences between their movements, and movements were not correlated with body size or environmental conditions. Individuals are able to move further than 100 m per day, a characteristic that may enable this species to colonize or recolonize open areas.
TL;DR: Skeletochronology applied to a sample of Iberian spadefoot toads from Serra da Arriça, an agro-forestal area in south-central Portugal marked by cool, rainy winters and hot, dry summers hypothesized that reduced growth rate is a consequence of lengthy, harsh summer conditions.
Abstract: We applied skeletochronology to a sample of Iberian spadefoot toads, Pelobates cultripes, from Serra da Arrica, an agro-forestal area in south-central Portugal marked by cool, rainy winters and hot, dry summers. These environmental conditions allow winter activities but constrain toads to a 12-16 week aestivation period. Lines of arrested growth (LAGs) in phalanges were easily readable albeit, unexpectedly, of varying distinctiveness. Double LAGs were scarce as predicted from the observation of a simple seasonal activity cycle. Limited endosteal resorption did not affect any LAG. Age of adult females ranged from 2-7 yr (N = 40) and that of adult males from 2-8 yr (N = 20). Mean adult snout-vent length (males, 52.8 mm; females, 54.2 mm) and growth rate were lower compared to other Iberian populations of spadefoot toads. However, von Bertalanffy growth curves predict much larger body sizes and greater longevity. We hypothesize that reduced growth rate is a consequence of lengthy, harsh summer conditions. Reduced longevity of spadefoot toads in the study area is probably related to local mortality factors, mainly road kill and land ploughing. Predictions of a postponement of age at sexual maturity at a smaller body size when conditions of reduced feeding and growth rate prevail were only weakly satisfied.
TL;DR: Brown Treesnakes recorded preferred body temperatures in the laboratory and compared these to operative temperatures obtained with copper models and Tbs obtained by radiotelemetry from 11 free-ranging snakes on Guam, finding that brown treesnakes exhibited elevated Tb into the higher range only in the evening.
Abstract: Few studies have focused on the thermal biology of tropical or nocturnal snakes. We recorded preferred body temperatures (Tb) of seven Brown Treesnakes (Boiga irregularis) in the laboratory and compared these to operative temperatures obtained with copper models and Tbs obtained by radiotelemetry from 11 free-ranging snakes on Guam. Operative temperatures on Guam did not vary across refuge types, unless the site received direct solar radiation. In a thermal gradient and on Guam, Brown Treesnakes thermoregulated around two distinct temperature ranges (21.3–24.9°C; 28.1–31.3°C). In the gradient, brown treesnakes exhibited elevated Tb into the higher range only in the evening. On Guam, snakes achieved Tbs in the high range only when direct solar radiation was available during the afternoon, a period when snakes were inactive. Higher mean Tbs on sunny days corresponded with observations of basking behavior.
TL;DR: A new species of Crytodactylus from Pulau Aur in the Seribuat Archipelago off the southeast coast of Peninsular Malaysia is differentiated from all other Sundaland species in having a unique suite of characteristics involving tuberculation, scale counts, and color pattern.
Abstract: A new species of Crytodactylus from Pulau Aur in the Seribuat Archipelago off the southeast coast of Peninsular Malaysia is differentiated from all other Sundaland species in having a unique suite of characteristics involving tuberculation, scale counts, and color pattern. This increases the total number of endemic species in the Seribuat Archipelago to at least 18 and is the second endemic gecko known from Pulau Aur.
TL;DR: The results indicate that Desert Tortoises in the Sonoran Desert occur at low density, but are not absent, from intermountain valleys, and the maintenance of these valleys for tortoise movement between local populations may be important for long-term population viability.
Abstract: Desert Tortoise surveys and management in the Sonoran Desert typically exclude intermountain valleys, where tortoises are generally thought to be absent. Furthermore, few regional-level surveys have been conducted because of difficulties in sampling in the complex landscape of Sonoran Desert upland habitat. We used distance-sampling to document macrohabitat use and regional density of Desert Tortoises across the 76,800-ha Ironwood Forest National Monument in Arizona. We observed 42 tortoises on transects, and distance sampling produced an estimate of 17,997 tortoises ≥ 150 mm carapace length (coefficient of variation = 41.5%) on the monument. Stratification by habitat type (steep topography with boulders, incised washes, or neither of these components) improved precision slightly (37.2%). Detection probability contributed least to density variance, compared to encounter rate and tortoise detectability on the transect line, indicating that assumptions of the technique were met during sampling. We ...
TL;DR: Using mark-recapture methodologies, the number of adult Wood Turtles inhabiting an agricultural site in southern Québec, Canada revealed that the adult population declined by 50% during this period, suggesting that this decline resulted from increased adult mortality and poor recruitment.
Abstract: Using mark-recapture methodologies, we estimated the number of adult Wood Turtles (Glyptemys insculpta) inhabiting an agricultural site in southern Quebec, Canada. Two estimates, made seven years apart, revealed that the adult population declined by 50% during this period. Different hypotheses likely to explain this situation are discussed, and, although none seems more likely than the others, our data suggest that this decline resulted from increased adult mortality and poor recruitment.
TL;DR: Radio-telemetry was used to study spatial ecology of a Cottonmouth population in eastern Texas, finding that sex, reproductive state, and body size on spatial use within a riparian habitat were examined, but body size did not account for observed home-range differences among population subunits.
Abstract: Radio-telemetry was used to study spatial ecology of a Cottonmouth (Agkistrodon piscivorus) population in eastern Texas. I examined effects of sex, reproductive state, and body size on spatial use within a riparian habitat. Snakes inhabited a relatively linear environment, restricting movements to the vicinity of the stream. Males occupied larger home ranges than both gravid and nongravid females. Gravid females exhibited marginally larger home ranges than nongravid females, but any effects attributable to reproductive state were relatively small when compared to sex differences in spatial use. Body size was positively correlated with home-range size but did not account for observed home-range differences among population subunits.
TL;DR: It is suggested that desiccation threat alone does not explain the species-specific differences in leech loads on aquatic turtles, and the rate of colonization is measured.
Abstract: It is generally accepted that bottom-dwelling turtles have a higher ectoparasite load than turtles that bask aerially because of effects of desiccation on ectoparasites, especially with regard to leeches. We compared number of leeches (primarily Placobdella parasitica) on field-caught Common Musk Turtles (Sternotherus odoratus) and Common Map Turtles (Graptemys geographica). The bottom-dwelling species S. odoratus had more than 20 times the number of leeches than the aerial-basking species G. geographica. We then exposed cleaned (leech-free) turtles to leeches in mesocosms (cattle tanks) to measure the rate of colonization. In this experiment, S. odoratus had more than four times the number of leeches as G. geographica after 24 h of exposure, even though G. geographica were unable to bask under these experimental conditions. We suggest that desiccation threat alone does not explain the species-specific differences in leech loads on aquatic turtles.
TL;DR: It is indicated that the microhabitat provided by tree buttresses forms a site of generalized high abundance for the leaf-litter herpetofauna and may contribute to localized high abundance of at least one species.
Abstract: We assessed the importance of tree buttresses as a microhabitat for leaf-litter amphibians and reptiles in a tropical wet forest in Costa Rica by making comparisons of species richness and abundance between pairs of 4 × 4 m leaf-litter quadrats. One quadrat in each pair contained a central buttressed tree, and the other did not. Both abundance and species richness of the herpetofauna were much greater in plots containing buttressed trees; higher species richness in buttress plots was attributed solely to greater abundance in these plots. Buttress and nonbuttress plots contained a similar species composition, and we found particularly strong use of this microhabitat by the scincid lizard Sphenomorphus cherriei. Our results indicate that the microhabitat provided by tree buttresses forms a site of generalized high abundance for the leaf-litter herpetofauna and may contribute to localized high abundance of at least one species.
TL;DR: Ecological differences between the two species may result in differential susceptibilities to habitat perturbation, with E. bilineatus being more tolerant of disturbed areas and perhaps even benefitting from anthropic action, unlike the forest-dependent E. brasiliensis.
Abstract: Aspects of the ecology of the semiarboreal lizards Enyalius bilineatus and Enyalius brasiliensis were studied in a montane Atlantic forest region of Espo ´rito Santo State, southeastern Brazil. Individuals of E. bilineatus were collected mainly in a coffee plantation, whereas E. brasiliensis was found only in the forest proper. Enyalius brasiliensis was significantly larger (up to 106 mm snout—vent length, SVL) than E. bilineatus (up to 90 mm SVL). Both species were sexually dimorphic in body size, with females larger than males. The two species consumed a broad spectrum of prey but differed quantitatively in their diet composition. Ants and orthopterans dominated the diet of E. bilineatus, whereas E. brasiliensis preyed mainly on cockroaches and caterpillars. Clutch size of E. bilineatus varied from 2-6 (mean 5 4.4) and that of E. brasiliensis from 8-14 (mean 5 11.5). Ecological differences between the two species may result in differential susceptibilities to habitat perturbation, with E. bilineatus being more tolerant of disturbed areas and perhaps even benefitting from anthropic action, unlike the forest-dependent E. brasiliensis.
TL;DR: It is proposed that males move more and cover more area than females early in the mating season to intercept receptive females.
Abstract: Texas Horned Lizards, Phrynosoma cornutum, were tracked using fluorescent powder to determine exact daily movements. Daily linear movements and daily space use were compared between adult males and females. Lizards that traveled the greatest linear distances also covered the largest areas. In Oklahoma, adults emerge from hibernation in late April and early May and mate soon afterward. Males traveled significantly greater distances (and covered significantly larger areas in a day) than females in May but not after May. We propose that males move more and cover more area than females early in the mating season to intercept receptive females.
TL;DR: It is concluded that P. spurcus is a valid species, distinct from P. patagonicus and all other Phymaturus, with additional data on intraspecific variation in both species.
Abstract: Phymaturus spurcus was described by Barbour in 1921. In 1931, Burt and Burt placed this species in the synonymy of Phymaturus patagonicus based on their comparison of one paratype of P. spurcus with one specimen of P. patagonicus. Additionally, Burt and Burt considered P. patagonicus a subspecies of Phymaturus palluma. Although some subsequent authors accepted the synonymy of P. patagonicus with P. palluma, the synonymy of P. spurcus with P. patagonicus has gone unquestioned. We examined the type series of P. patagonicus and P. spurcus, as well as new material collected from the type localities of both species. Based on 47 morphological characters of squamation, gular and nuchal folds, precloacal pores, and morphometric data, we conclude that P. spurcus is a valid species, distinct from P. patagonicus and all other Phymaturus. We agree with Cei and Castro's study in 1973 that the population located west of Dolavon, Chubut Province, Argentina, is P. patagonicus of Koslowsky' study in 1898 Because in the original description Koslowsky failed to designate an holotype, we designate Museo La Plata S-778 as the lectotype of P. patagonicus and restrict its type locality to 40 km west of Dolavon, Chubut Province, Argentina. We provide a redescription of P. patagonicus Koslowsky and a redescription of P. spurcus based on the type series of Barbour's study in 1921, with additional data on intraspecific variation in both species.
TL;DR: Gambelia sila generally became active in April, and activity remained relatively high into July, and differences in daily activity varied and were moderately well explained by environmental factors.
Abstract: We captured 1078 Blunt-Nosed Leopard Lizards (Gambelia sila) 2396 times between 1989 and 1994 on the Elkhorn Plain, San Luis Obispo County, California. Based on size at first capture, we caught 119 adult (� 90 mm snout-vent length (SVL)) and 430 hatchling/juvenile (<90 mm SVL) males, and 139 adult and 390 hatchling/juvenile females. Sex ratio of males to females was 1.04 (549 males/529 females). Adult G. sila generally became active in April, and activity remained relatively high into July. Hatchlings were first noted in either July or August and generally could be found until early November, except in 1990 when no hatchlings were found at any time. Mean number of adults and hatchlings found active each day differed significantly across years, but as many as 32 adults and 42 hatchlings were seen on a plot during a census. Estimates of population abundance on a plot also varied yearly from 20-164 adults and 0-273 hatchling/juveniles and seemed to be affected either by too little or too much rain. Differences in daily activity varied and were moderately well explained by environmental factors. We estimated survivorship of lizards and found 29.0% of hatchlings from 1992 survived to 1993, and 14.6% of hatchlings from 1993 survived to 1994. The oldest G. sila found was a female estimated to be 4 years, 10 months when last caught, although most adults were not seen after 2 yr. Growth of individuals varied by year: highest growth rates were for lizards that hatched in 1991 and 1992, and lowest growth occurred in lizards that hatched in 1989. We found adult leopard lizards with eggs in all years but 1990. Females generally were gravid by late April or early May, and some females were found with eggs in early July. Female size at first reproduction was about 90 mm SVL, clutch size ranged from 1-6 eggs, and overall mean clutch size regardless of year or clutch order was 3.4 eggs. Many females produced multiple clutches in a year, and we found up to four clutches by a single female.
TL;DR: Male Dendrobates pumilio are territorial, and vocalize in the presence of intruders, which suggests that both neighbors and strangers may compete with residents for territory and mates.
Abstract: Male Dendrobates pumilio are territorial, and vocalize in the presence of intruders. Territory displays are energetically expensive, and residents should modify display behavior according to costs and benefits associated with social contexts of intrusions by conspecifics. Activity censuses found no significant difference in the proportions of male and female D. pumilio found at various times of day, but a higher proportion of animals that were active at 0730 were male. Resident males exhibited a significantly greater mean call group duration when faced with male intruders in the morning than in the afternoon but did not respond differently to male or female intruders. This may reflect greater potential benefits of repelling territorial intruders in the morning than in the afternoon and use of the same territorial displays to defend territory boundaries as well as to attract potential mates. No significant differences were found in responses of resident males to familiar and unfamiliar conspecifics, which suggests that both neighbors and strangers may compete with residents for territory and mates.