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In 2003, southern California experienced several large fires that burned thousands of hectares of wildlife habitats and conserved lands. To investigate the effects of these fires on the reptile and amphibian communities, we compared the results from prefire herpetofauna and vegetation sampling to two years of postfire sampling across 38 burned and 17 unburned plots. The sampling plots were spread over four vegetation types and four open space areas within San Diego County. Our capture results indicated that burned chaparral and coastal sage scrub plots lost herpetofaunal species diversity after the fires and displayed a significant shift in overall community structure. Shrub and tree cover at the burned plots, averaged across the second and third postfire years, had decreased by 53% in chaparral and 75% in coastal sage scrub. Additionally, postfire herpetofauna community structure at burned plots was more similar to that found in unburned grasslands. In grassland and woodland/riparian vegetation plots, where shrub and tree cover was not significantly affected by fires, we found no differences in the herpetofaunal species diversity or community composition. At the individual species level, Sceloporus occidentalis was the most abundant reptile in these areas both before and after the fires. We saw increases in the net capture rates for several lizard species, including Aspidoscelis tigris, Phrynosoma coronatum, and Uta stansburiana in burned chaparral plots and Aspidoscelis hyperythra and U. stansburiana in burned coastal sage scrub plots. The toad, Bufo boreas, was detected at significantly fewer burned plots in chaparral after the fires. Additionally, we documented decreases in the number of plots occupied by lizards (Elgaria multicarinata), salamanders (Batrachoseps major), and snakes (Coluber constrictor, Lampropeltis getula, Pituophis catenifer, and Masticophis lateralis) in coastal sage scrub and chaparral after the fires. We discuss the individual species results as they relate to such life-history traits as the susceptibility to initial mortality, the response to the altered postfire habitat, and shifts in the availability of potential prey. We foresee that a continued unnatural fire regime will result in a simplification of the southern California reptile and amphibian communities.
Female Hawksbill Turtles (Eretmochelys imbricata) nesting along the southeast coastline of the state of Rio Grande do Norte Brazil (6°13′40″S, 35°03′05″W) were captured and weighed during the 2006–07 and 2007–08 nesting seasons. The mean value for the first postoviposition mass was 79.6 kg. Individuals that were subsequently recaptured showed a mean mass change of 1.6 kg in the interval between two consecutive postovipositions (i.e., after one internidal interval). We plotted the mass of the individuals against the curvilinear carapace length. An analysis of residual mass above average body condition reveals that females with good body condition start nesting at the beginning of the season. Preoviposition mass was measured when the female aborted the nesting process. Gross mass change was 5.46 kg. Mean body mass recovery was 3.2 kg. Body mass recovery was always significantly lower than the change in gross mass. This is in agreement with the observed mass loss tendency throughout the breeding season for this species. Mass recovery was analyzed using allometric law, converting both loss in body mass and total egg mass to energy. Using mean turtle body mass, we performed three scenarios for the metabolic maintenance rate of the Hawksbill Turtle during the nesting period. The energy that the turtles expended in egg laying was estimated at 1,183 kJ • d−1. The daily net mass loss for the most realistic scenario converted into energy was 4,213 kJ • d−1. The total daily energy consumption (maintenance plus egg production) was similar to the daily energy from mass loss. This theoretical treatment suggests that, under this scenario, there is no reason for significant extra energy intake during the oviposition period.
We describe the advertisement call, tadpole, karyotype, and additional information on the natural history of Cycloramphus lutzorum from southern Brazil. Sonograms were generated from digitally recorded calls. Tadpoles were collected in the field for description in the lab, and an adult was collected for karyotyping. Data on seasonal activity were gathered monthly from November 2005 to November 2007. All tadpoles (N = 21), juveniles (N = 18), and adults (N = 52) were found exclusively in streams. Reproduction, as identified by calling frogs, occurred from July through November. Frogs call all day long, but mostly at dusk, from rock crevices inside the stream edges near the splash zone. The call is short and loud, with 11 pulsed notes, of 491–641 ms, with a dominant frequency of 0.98–1.39 kHz. We describe the exotrophic and semiterrestrial tadpoles, always found in constantly humid vertical rock walls in the stream. Tadpoles of C. lutzorum are recognized by differences in labial tooth row formula, eye diameter, body shape, position of nares, and development of tail. Like congeneric species, the karyotype of C. lutzorum comprises 26 metacentric and submetacentric chromosomes. Cycloramphus lutzorum is restricted to and adapted for living in fast flowing streams, many of which are threatened by deforestation, pollution, and habitat loss. Therefore, we recommend the status of C. lutzorum be changed from its current “Data Deficient” to “Near Threatened (NT)” in the IUCN species red list.
Distance sampling methods to estimate population densities are in wide use; however, this method may not be suitable for certain species or in certain habitats. Although validation of population estimates derived from distance sampling is necessary to determine the reliability of population estimates, validation is lacking in most studies. We measured densities of six lizard species, with particular emphasis on the endemic Dunes Sagebrush Lizard (Sceloporus arenicolus) at 14 sites throughout the range of this species in the Mescalero Sands ecosystem in southeastern New Mexico. We tested the accuracy of distance sampling by comparing results from 238 distance line transects to densities measured in 20 total removal plots. Density estimates from the distance sampling method (N = 238 transects) for S. arenicolus and all lizard species combined were 4.6 lizards/ha and 26.14 lizards/ha, respectively. Density estimates from the total removal plots (N = 20) were 30.0 lizards/ha for S. arenicolus and 85.0 lizards/ha for all lizard species combined. It is clear that, even in the relatively open shinnery oak sand dune habitat, distance sampling methods were not reliable and underestimated the densities of lizards. The disparity in density estimates from distance sampling versus total removal plots was caused by violation of the assumption of perfect detection of individuals on the transect line. Individuals that were unavailable for detection greatly influenced the density estimates. Because of the difficulty in correcting for biases, we suggest that distance sampling is not an appropriate sampling method for estimating densities of lizards.
Fowler's Toad (Anaxyrus fowleri) was historically abundant and widespread in various habitats, including urban and agricultural areas, in southern Louisiana. Coincident with intense anthropogenic disturbance, the abundance of the Coastal Plain Toad (Incilius nebulifer) has increased significantly in degraded habitats. Subsequently, A. fowleri is found only in forested areas near permanent water bodies that are not preferred breeding habitat of I. nebulifer. We hypothesized that larval competition with I. nebulifer, a species that breeds in extremely ephemeral habitat commonly found in disturbed areas, contributed to A. fowleri's decline. We raised tadpoles in intra- and interspecific competition in artificial ponds under simulated permanent and temporary breeding habitat conditions. Competition with I. nebulifer tadpoles, but not pond drying, resulted in a decrease in body size measures and a lower rate of survival to metamorphosis for A. fowleri tadpoles. Incilius nebulifer tadpoles were slightly larger in drying than in permanent ponds and were larger and had a higher rate of survival to metamorphosis in interspecific tanks than in intraspecific tanks, suggesting that it is easier for I. nebulifer to outcompete other species than conspecifics. The Coastal Plain Toad's superior competitive ability in temporary breeding sites may have resulted in ecological displacement and is potentially contributing to a decline of regionally sympatric populations of Fowler's Toad in degraded landscapes.
This study combines three experiments that identify how Wood Frog (Rana sylvatica) tadpoles assess risk from chemical cues produced by larval dragonflies (Anax junius) preying on conspecifics. I also compare the results to previous studies using Green Frog (Rana clamitans) tadpoles. The results suggest that Wood Frog tadpoles largely assess predation risk through Anax chemical cues similarly to Green Frog tadpoles. This is to be expected because the tadpoles are congeneric and both face predation from Anax in the field. However, their behavioral response to a particular level of perceived risk differs. Wood Frog tadpoles reduced their total activity (swimming and feeding) for a shorter time than Green Frog tadpoles. Wood Frog tadpoles also reduced their feeding activity more strongly than their swimming activity during cue exposure. I relate the differences between the behavioral responses of Wood Frog and Green Frog tadpoles to differences in their life-history strategies.
For 16 years, we have observed and recorded seasonal life cycles of individual free-ranging Rosenberg's Goannas, Varanus rosenbergi. These monitor lizards are normally solitary except during their annual summer breeding cycle. Activities and behaviors were documented from precourtship through to pairing, courtship, copulation, selecting and excavating an incubation chamber, egg laying, and finally guarding the egg mound before returning to a solitary life style. Whereas the sequence of breeding activities tends to follow a set pattern, the timing and duration of physical and physiological events vary from season to season. Courtship through to defending the egg mound occupies up to 4 months of the year, commencing just before the summer solstice and ending shortly after the autumn equinox.
Tadpoles of two sister species of Ameerega are described. Tadpoles of Ameerega parvula can be distinguished from those of A. bilinguis based on slight differences in their oral disc structure and configuration of the tail fin. Both tadpoles have a tooth row formula 2/3 that is typical for many Ameerega, Epipedobates, and Allobates species. The two species differ in the relative length of the second lower tooth row (P-2). Ameerega parvula tadpoles have a slightly longer P-2 than P-1 row, whereas the P-2 row of A. bilinguis tadpoles is shorter than their P-1. The upper fin at midtail is slightly wider than the lower fin in A. parvula, whereas the lower fin is slightly wider than the upper fin in A. bilinguis tadpoles. Both tadpoles can be discriminated from those of sympatric species based on color and oral disc morphology. However, the oral disc morphology of Ameerega tadpoles provides no synapomorphic characteristics to distinguish Ameerega tadpoles from other dendrobatoid genera.
The jaguar (Panthera onca) is the largest Neotropical felid and in many parts of its range reptiles form a significant but relatively minor component of its diet. However, in the seasonally flooded varzea forests of the Amazon, terrestrial mammals, which form an important component of jaguar diet in other habitats, are largely absent and jaguars switch to alternative prey, including arboreal mammals and reptiles. In the Mamirauá Sustainable Development Reserve in the western Brazilian Amazon, we document predation by jaguars on two species of caiman (Caiman crocodilus and Melanosuchus niger), which are abundant in this varzea habitat. The smaller C. crocodilus seems to be particularly vulnerable because of its size and tendency to spend more time on land than the larger M. niger. Jaguars not only kill and eat caiman but are also a significant predator on eggs of both species. We place our findings into the context of jaguar predation on reptiles by reviewing studies of jaguar diet in a variety of biomes.
Many predation risk factors operate similarly in closely related taxa, but ecological and other differences among prey species may expose them to different risks in similar circumstances. We compared escape responses by the syntopic lizards Sceloporus jarrovii and S. virgatus to similar risk factors: perch height, predator approach speed, predator persistence, and direction of predator turning. Flight initiation distance (predator–prey distance when escape begins) decreased as perch height increased in both species but was shorter in S. virgatus. Sceloporus jarrovii fled except when perch height was above 2 m., but S. virgatus often did not flee even at low perch heights. These differences may reflect lower detectability of S. virgatus, which is difficult to detect on shaded sides of tree trunks and typically escapes without climbing out of reach. Flight initiation distance was greater for the faster and second of two approaches in both species. Sceloporus jarrovii fled more frequently than S. virgatus when a nearby investigator turned away from, but not toward, a lizard. At low perch heights and when a nearby predator moves, the larger S. jarrovii is warier than S. virgatus, which may rely relatively more on crypsis than escape. Similarity of responses to some risks by both species might reflect retention of ancestral behaviors or convergence. Escape differences seem to occur when risk operates differently due to ecological differences, suggesting that aspects of escape may be molded by natural selection with at least partial independence, resulting in escape strategies suitable to the ecologies of each species.
The Bokermannohyla martinsi species group includes two species, B. martinsi and B. langei. Bokermannohyla martinsi is found mainly in rocky permanent streams, associated with gallery forests in the highlands of the southernmost portion of the Espinhaço Mountain Range, Brazil. Its tadpoles have robust, oval/ovoid in lateral and dorsal views, black bodies, and a muscular tail. External morphology, color in life and in preservative, and detailed morphometric data are presented, as well as natural history notes for the species. Diagnostic characteristics that help distinguish B. martinsi tadpoles from other species within the B. circumdata, B. pseudopseudis, B. alvarengai, and B. claresignata groups are as follows: labial tooth row formula, absence of a median gap on the anterior row of marginal papillae, and black coloration of the body and tail. Data on microhabitat use available for five species of Bokermannohyla indicate that their tadpoles have broad niches, being able to exploit many types of microhabitats (e.g., substrate type, depth, current, and vegetation presence or absence) throughout the year within the streams where they occur. Regardless of the available microhabitats in the sampling sites, tadpoles showed high niche overlap, rendering their differentiation based on microhabitat use unlikely.
Mining can result in severe physical and chemical alterations of landscapes. Tar Creek Superfund Site, located in northeastern Oklahoma, was mined extensively for lead and zinc from the early 1900s until the 1970s and remains heavily damaged. We investigated the ecology of Red-Eared Slider Turtles (Trachemys scripta) from Beaver Creek within Tar Creek Superfund Site and two reference sites, Lake Carl Blackwell and Sequoyah National Wildlife Refuge. We measured parameters, including body size, sex ratios, sexual dimorphism indices, and recapture and survival rates. Sex ratios were female biased at Tar Creek Superfund Site and Lake Carl Blackwell and male biased at Sequoyah National Wildlife Refuge. Degree of sexual size dimorphism differed significantly among the three sites. Male T. scripta were significantly larger at Lake Carl Blackwell than at Tar Creek Superfund Site and Sequoyah National Wildlife Refuge. Females from Tar Creek Superfund Site were significantly larger than females from Lake Carl Blackwell. Survival and recapture rates did not differ significantly among the sites. Overall, we found no significant, consistent differences in population demographics of T. scripta inhabiting mined and unmined sites.
Although investigators have determined that some anurans can influence nutrient availability in terrestrial systems, ecological interactions among salamanders, invertebrates, and leaf litter decomposition in the detrital ecosystem are poorly understood. We examined the effects of the Eastern Red-Backed Salamander (Plethodon cinereus) on leaf litter decomposition rates and invertebrate populations in the mixed oak forests of southwestern Virginia from May 2006 to June 2008. We constructed 12 in situ mesocosms with 0, 1.0, or 2.0 P. cinereus/m2 (4.0 P. cinereus/m2 in year 2). We quantified decomposition rates of leaf litter and numbers of invertebrates with litter bags that were removed from mesocosms monthly throughout the experiment. Further, we assessed what taxa of invertebrates were preyed upon by salamanders with gastric lavage. Across our 2-year experiment, we were unable to detect an effect of salamander abundance on rates of leaf litter decomposition, numbers of broad invertebrate taxonomic groupings, or functional guilds of invertebrates. Stomach analysis confirmed that salamanders were euryphagic, but they consumed more herbivores than detritivores or predators. Although we are unclear why these results conflict with earlier work indicating that salamanders can influence invertebrates and leaf litter decomposition, variability of canopy trees or microclimate may have contributed to a lack of control of invertebrate populations or litter decomposition by salamanders in the complex mixed-oak forests of the Appalachian Mountains.
We analyzed variation in the advertisement calls among three localities of Eleutherodactylus glamyrus, a frog endemic to the Sierra Maestra mountains in Eastern Cuba. We assessed the levels of within-male variation of each call property and the influence of temperature and size of calling male on acoustical features. The typical single-note advertisement call of the species was described using temporal and spectral parameters. Rise time and frequency modulation were highly variable within individuals, whereas dominant frequency and call duration were the most stereotyped properties. Call rate showed an intermediate level of variation. Air temperature strongly influenced call rate and call group duration. Snout–vent length (SVL) strongly influenced dominant frequency and rise time. Localities differed in call rate, call duration, and rise time. This acoustic differentiation might be the result of past divergences arising from a distribution gap between the two mountain massifs surveyed. Because acoustical features are increasingly used in interspecific or intraspecific comparisons in the genus Eleutherodactylus, we encourage researchers to assess whether temperature or SVL have sufficiently important effects on their data and use statistical procedures to remove these confounding factors. The multinote call of the species is quantitatively described for the first time. This call type resembles that of other members of the genus and probably carries an aggressive message.
Understanding how potential predator cues and habitat features affect predation of turtle nests is important because nest predators can influence the demographic structure of turtle populations. We constructed artificial turtle nests in an area used by nesting Painted Turtles (Chrysemys picta) to investigate the relative importance of visual and olfactory signals (both natural and anthropogenic) and edge effects on nest predation. Overall, 34% of the simulated nests displayed evidence of predation. Neither rocks or flags used to mark nests (visual and olfactory cues left by researchers) nor slough water (an olfactory signal inadvertently shed by nesting turtles) significantly influenced predation rates. Instead, predators (most likely raccoons) located artificial nests based solely on surface soil disturbance and proximity to habitat edges. These results suggest that predators use key natural cues (as opposed to anthropogenic markers) and habitat edges to locate Painted Turtle nests, as noted in prior observational studies at this site. These findings provide useful experimental insights into the impact of anthropogenic markers, surface soil disturbance, and habitat edges on nesting turtles and their predators.
Body temperatures (Tb) of eight free-ranging Heterodon platirhinos were measured with radiotelemetry throughout the year. Body temperature ranged from 5–37°C and varied with air temperature and activity. During the active season, Tb of active snakes (∼30.5°C) averaged about 3°C higher than that of inactive snakes (∼27.4°C). Body temperature did not differ between the sexes or between resident and nonresident snakes. At air temperatures below 30°C, Tb averaged ∼3°C above air temperature; at air temperatures above 30°C, Tb averaged ∼0.2°C below air temperature. Basking appears to be important in the thermal ecology of H. platirhinos. Body temperature of free-ranging active H. platirhinos monitored with radiotelemetry was similar to previous reports on Tbs of active H. platirhinos measured with cloacal thermometers. A thorough knowledge of basic thermal requirements of H. platirhinos may be useful in its conservation.
Male and female African Clawed Frogs (Xenopus laevis) produce calls and engage in dueting in both silt-filled ponds and laboratory aquaria. Previous research has established that males produce different answer calls in response to receptive (11–12 Hz click rate) and nonreceptive (click rate of 4 Hz) female calls. In the present study, in addition to male answer calls, male phonotropism behaviors were measured for the first time during playbacks of natural female rapping and ticking calls as well as synthetic stimuli consisting of ticking calls with 90-msec interclick intervals (ICIs) and rapping calls with 250-msec ICIs. Also, the results show that males approach a loudspeaker significantly more often in response to rapping calls and remain longer in the proximity of the speaker. Moreover, males produce answer calls more frequently in response to female rapping calls and produce few answer calls in response to female ticking calls. Synthetic ticking calls with 90-msec ICIs evoked an intermediate phonotaxis response, whereas synthetic rapping calls with 250-msec ICIs evoked the same level of phonotaxy as do natural ticking calls. These results show that male phonotaxy is strongly, although not entirely, determined by the rhythmic characteristics of female calls, whereas antiphonotaxy appears to be determined by female call rhythm alone.
Here we describe the tadpoles of Rhinella jimi. Rhinella jimi tadpoles are benthic and exotrophic and display aggregative behavior. These tadpoles can be distinguished from other members of the Rhinella marina group by the combination of the following characters: spiracle with external tube opening on midbody; snout sloped in lateral view; eyes and nostrils proportionally larger than in Rhinella schneideri. Finally, we reviewed the information available on the other described tadpoles of the R. marina species group and compare them with the tadpole of R. jimi.
We fit asymptotic models to growth data of free-ranging Gila Monsters studied near Tucson, Arizona. We used a mixed-effects modeling procedure that allows for unequal numbers of recaptures by accounting for within-individual covariance and models between-individual variation in growth parameters as random effects. A model selection procedure and diagnostic tests indicated that a von Bertalanffy curve with seasonal cessation of growth and a random effect for asymptotic size fit the data best. Young Gila Monsters in our study grew faster than previously reported growth rates from both field and captive animals, and we discuss potential reasons for this discrepancy.
Little is known about the diet of many amphisbaenians and even less about their prey preferences in part because of their fossorial habits. We used the tongue-flicking behavior of an amphisbaenian, Amphisbaena heterozonata, an apparently opportunistic feeder, to investigate its ability to discriminate among three prey items: termites (fed in captivity), tenebrionid larvae, and earthworms. We tested 16 individuals, placing each one in a glass tube, in a room lighted only with a red light to simulate fossorial conditions. Stimuli were presented on cotton swabs impregnated with the smell of a prey, using distilled water as control. Two experiments were conducted: in the first, the amphisbaenians had not eaten one week prior to starting the experiment; and in the second, they had not eaten two weeks prior to it. The number of tongue flicks per minute and latencies to the first tongue flick were recorded. The amphisbaenians made significantly more tongue flicks to termites than to the water control in both experiments. In addition, latencies were significantly shorter toward termites than toward water. The results show that A. heterozonata could clearly discriminate, based on chemical stimuli, between termites, one of the prey items they feed on in the field and on which they were fed in captivity, and water. Other comparisons among prey items and the water control were nonsignificant except in two cases during the second experiment. Considering that this species is most likely a generalist–opportunistic feeder, the results may indicate that the response was learned based on its year-long termite-exclusive diet.