The reproductive cycle and cycles in fat body and liver mass are described for male and female Sceloporus utiformis from Chamela, Jalisco, México, during 1988 and 1990. These cycles varied among months and between sexes. Males reached sexual maturity at 45 mm snout–vent length (SVL) at an age of seven months. Females reached sexual maturity at 56 mm at an age of nine months. Testes of males began to increase in volume in early May, and maximal testicular activity occurred from June to October. Testis size began to decrease in November and was small in December. Reproductive activity of females occurred between July and March. Gonads of females began to increase in volume in mid-June, and maximal egg production was from August to November. Maximal testicular growth was positively correlated with increasing temperature and precipitation, but not with photoperiod, whereas in females follicular growth was positively correlated with photoperiod but not with temperature and precipitation. Egg production occurred primarily during the wet season and early dry season. Females started to lay their eggs in late July. Mean (± SE) clutch size of oviductal eggs (6.94 ± 0.28) and vitellogenic follicles (7.3 ± 0.3) were not significantly different. Clutch size was significantly correlated with female SVL (r = 0.26, P < 0.05) and varied between years and months, as in other lizard species, presumably reflecting the effects of annual variation in resource availability on females.

We conducted a quantitative analysis of adult and juvenile Eleutherodactylus coqui (coquí) habitat preferences in Puerto Rico. The analysis consisted of two surveys: one to quantify potential habitat and another to quantify habitat use. Coquís were found to use most habitats available to them; however, adults and juveniles preferred different plant species, habitat structural components, and heights from the forest floor. Adult and juvenile coquís had opposite associations with many important plant species in the forest (e.g., Prestoea montana and Heliconia carabea) and habitat structural components. Adults had a negative association with leaves and a positive association with leaf litter. Juveniles showed the opposite trend. Adults were more evenly distributed with respect to height than were juveniles, with adults preferring heights around 1.1 m and juveniles preferring heights closer to the forest floor. The quantitative survey technique for determining habitat preferences used in this study generally confirmed coquí habitat preferences known from qualitative assessments.

We examined the reproductive output of spotted turtles (Clemmys guttata) from a population in South Carolina. We used radio telemetry, palpation, and x-rays to monitor the reproductive condition of females over two field seasons. We present the first evidence for multiple clutching in a wild population of spotted turtles. Of 12 females with radio transmitters that became gravid, five produced second clutches, and one produced a third clutch. Average annual clutch frequency was 1.2 per female. Clutch frequency was independent of body size. We compared reproductive output among three populations: Ontario, Pennsylvania, South Carolina. Individual clutch sizes varied with latitude. Clutch size was largest in the north (mean = 5.3 eggs), midsized in the central population (3.9), and smallest in the south (2.9). We suggest that this pattern is related to seasonality differences, which result in different selective pressures on body size of females. Total annual egg production (the sum of all clutches within a reproductive season) by gravid females did not differ between the Ontario (5.3 eggs) and South Carolina populations (4.6). These data indicate that, although individual clutch sizes differ between northern and southern spotted turtles, total annual reproductive output is consistent in these widely separated populations.

Ambystoma gracile (Baird) and Ambystoma macrodactylum Baird are common salamander species occupying key trophic positions in mountain ponds and lakes of Mount Rainier National Park (MORA). Based on amphibian surveys conducted in ponds and lakes in the northeast quadrant of MORA during the summers of 1993–1995, 20 sites were resampled in 1996 to document and evaluate distributions of the two species relative to site habitat characteristics. Distributions of larvae were assessed either by nearshore snorkel or visual encounter surveys of each study site. Twelve environmental variables representing pond and lake physical characteristics, water quality, and nutrient concentrations were measured. The occurrences at each site of three major habitat components (i.e., pond bottom firmness, coarse woody debris, and emergent/aquatic vegetation) were qualitatively estimated. Allotopic distributions of larval populations of both species were related to site elevation, maximum depth, organic content of bottom substrates, and surface area. Ambystoma gracile sites were larger, deeper, lower in elevation, had flocculent sediment higher in organic content, abundant coarse woody debris, and limited emergent/aquatic vegetation relative to A. macrodactylum sites. Ambystoma macrodactylum sites were smaller, shallower, higher in elevation, had firm sediments low in organic content, and had a greater occurrence of emergent/aquatic vegetation than did A. gracile sites. Two sites supported syntopic populations and exhibited many of the habitat characteristics observed at sites inhabited by each species. The distribution of each species in MORA was related to the interconnection between habitat characteristics of ponds and lakes and species life-history patterns and possibly interspecific interactions.

We studied the reproductive characteristics of a population of Cnemidophorus lemniscatus in a highly fragmented tropical dry forest with a bimodal rainfall regime. Females were smaller than males in snout–vent length (SVL) and head size. Males reached sexual maturity at 48 mm SVL and showed continuous spermatogenesis and spermiogenesis. The smallest vitellogenic female measured 51 mm SVL. We found vitellogenic and ovigerous females throughout the year and did not observe reproductive stage differences among months of the year. These data, plus the observation of neonates in every month of the year, confirm a pattern of continuous reproductive activity with multiple clutching. Clutch size varied from one to three eggs (mean of 2.17 ± 0.48) and was positively correlated with female SVL. Fat bodies were lacking in approximately 40% of the individuals. Mean fat-body mass did not vary among months for males or females; there were no differences in relative mass of stored fats between sexes. In spite of the marked seasonality of rainfall at this site, the population exhibited an aseasonal reproductive pattern that suggests a continuous availability of resources for reproduction.

We describe a new species of Acanthixalus from southwestern Ivory Coast. Acanthixalus sonjae sp. nov. differs from the Central African Acanthixalus spinosus genetically by 4.6 % in the investigated 16S rRNA. Morphologically adult frogs are very similar to A. spinosus. Male A. sonjae have wider heads and probably smaller gular glands than A. spinosus. Tadpoles of A. sonjae differ by much longer tails. Acanthixalus sonjae males are apparently mute. The new species is semiaquatic and lives in large water-filled cavities of trees in secondary and primary rain forest. Tadpoles complete metamorphosis in three months. They are at least partly carnivorous.

Anoles (Anolis, Chamaeleolis, Chamaelinorops, Phenacosaurus) differ greatly in size and shape of their subdigital toepads. We sampled 79 anole species to address two issues. First, is toepad size significantly related to habitat use? Second, do anoles from mainland Central and South America differ from Caribbean anoles in either the size of their toepads or in the relationship between toepad shape and habitat use? Among all anoles, toepad size increases with both perch height and diameter, although when the effects of body size are removed, these relationships are weakened. Morphological differences exist between toepads of anoles from the two regions. Caribbean anoles have larger toepads relative to snout–vent length and wider pads at larger body sizes compared to mainland species. Relationships between toepad morphology and habitat use characteristics do not differ significantly between the two groups of anoles. However, with effects of size removed, Caribbean anoles have larger and wider toepads relative to both perch height and diameter. These findings suggest that anoles in island habitats may require larger toepads than mainland anoles to use their arboreal habitats. The potential functional consequences of these differences in toepad morphology provide a promising avenue for future studies.

Altitudinal variation in larval growth and development rates in low- and high-altitude populations of two subtropical species of frog, Litoria chloris and Litoria pearsoniana was examined in the field using reciprocal transplant experiments. The larvae of both species raised at high altitudes (regardless of tadpole origin) had slower development rates than larvae raised at low altitudes. Slower growth rates were found in larvae from high altitudes in L. chloris, whereas a similar (but not significant) trend was recorded in L. pearsoniana. Despite slower growth rates overall, tadpoles raised at high altitudes tended to be larger at each Gosner Development Stage than those raised at low altitudes independent of tadpole origin. These results suggest that most of the variation in growth and development rates in the two species was caused by environmental factors (water temperature) rather than genetic or maternal factors. Tadpole survival in either species did not appear to be significantly affected by environmental or genetic factors in this study.

Many larval amphibians respond to predators by developing broad tail fins that increase maneuverability and reduce predation risk. Recent evidence also indicates that amphibian embryos may adaptively alter their time at hatching in the presence of a predator, but the generality of this phenomenon is unknown. We examined whether embryos of the Wood Frog (Rana sylvatica) and Spotted Salamander (Ambystoma maculatum) would alter hatching time, hatching synchrony, or body morphology in the presence of a larval predator. Using a 2 × 2 factorial design, we exposed developing embryos to four experimental treatments that varied in predation risk: unfed Anax junius (an odonate predator), fed A. junius, conspecific larvae, or water. Response variables were central tendency (mean or median) and variation (CV or range) for hatch time and developmental stage and four linear body dimensions that were used to detect changes in morphology. Effect sizes were small (< 0.36), and none of the response variables differed significantly among treatments, suggesting that embryos of these species do not respond strongly to the presence of a predator. This and other studies indicate that the response of amphibian embryos to predators varies both within and between taxa, although the adaptive significance of such variation is poorly resolved. We discuss the possible roles of developmental constraints and natural selection in explaining the lack of strong responses of Rana and Ambystoma embryos to a dangerous larval predator.

Although several investigators have discussed different herpetofaunal sampling methodologies and their effectiveness, few have quantitatively examined which methods are superior for inventorying reptiles and amphibians in rain forest habitats. I examined two years of data from Tambopata, southeastern Peru, to compare and contrast visual encounter survey (VES) and quadrat methodologies and to determine which method yields the highest number of individuals and species per sampling effort. Four separate questions were posed concerning the number of captures for short-term surveys, long-term surveys, arboreal versus terrestrial amphibian surveys, and particular taxonomic group surveys. Over most of the analyses, more individuals and species of amphibians and reptiles were captured using VES than quadrats. In addition, more unique species were recorded with VES. However, particular microhabitats and taxonomic groups were better sampled with quadrats. In long-term surveys, the methods were equivalent with respect to number of individuals and species captured. This study provides quantitative data on the efficacy of the two methods and describes, for the first time, the particular instances in which the different methods are best suited for sampling rain forest herpetofauna.

Evidence suggests that coevolution of a suite of ecological, behavioral, morphological, and physiological traits has accompanied the elaboration of niches of Caribbean Anolis lizards. Yet, information is lacking as to the extent to which energy expenditure is coadapted with the thermal or structural niche. I tested the prediction that body mass and standard metabolic rate (SMR) would covary with the thermal or structural niche of Anolis lizards. An analysis of standardized independent contrasts indicated that lizards occupying cooler thermal niches (at higher elevations) had relatively low mass-independent energy costs. Mass-independent SMR at 30°C was significantly related to the species' thermal niche (r = 0.88, P = 0.02). Other associations with structural niche and body mass were suggested. Possible causes of shifts in energy expenditure with changes in niche are discussed.

A new species of Hyalinobatrachium is described from the highlands of Guyana. This is the third centrolenid species reported from Guyana and the second of the genus Hyalinobatrachium. The new species is one of 13 Hyalinobatrachium found in northeastern South America (Venezuela, Guyana, Surinam, and Guyane); it can be differentiated from Hyalinobatrachium taylori, the only other Hyalinobatrachium in Guyana, by the color of the bones, which are white, and the color of the dorsum in preservative (lavender vs. cream in the new species). Variation and relationships within the genus in this region are discussed. The tadpole of the new species is described and illustrated.

Many reptiles have different habitat requirements for different activities (e.g., hibernation and nesting/gestation) that may not be satisfied by a single location. Suitable habitat may not only be limited, but also fragmented, making it difficult for animals to move between sites. In this study, we examine habitat use and movement patterns of Northern Alligator Lizards (Elgaria coerulea) and Western Skinks (Eumeces skiltonianus). In particular we determine the characteristics of hibernation and summer sites for both species and the extent of movement in both species, particularly whether migration occurs between summer and winter habitats. We used mark-recapture (PIT-tags and toe-clips) to do this. Both species coexisted at many of the same study sites, although some sites had only one of the species, and individuals were found in approximately the same locations in spring, summer, and fall. Thus, hibernation apparently occurs in the same habitat where lizards are active during the summer and no seasonal migration occurs. In fact, individuals of either species were recaptured on average within 10 m of a previous capture. Both species were rarely found in the open and more often under rocks than in vegetation or under logs; they also remained close to shrubs and forest edges. Roads apparently are not a major hazard for either species because they have high site-fidelity and do not make long-distance movements between hibernation or summer sites. Their requirement for cover means that any disturbance or removal of rocks from their habitats would be detrimental to both species.

Hatchlings of Leptodactylus fuscus can survive up to several weeks in their foam nests. Field observations showed that later-stage tadpoles could survive several days under leaves or rocks if their pool dried out. Laboratory experiments investigated the basis of these different out of water survival capacities and compared them to three other species. Recently hatched groups of tadpoles of L. fuscus on a damp substrate generated foam whose quality varied with the level of hydration of the substrate: at high hydration, the mucus of the foam drew water from the substrate, but at low hydration, water was drawn from the tadpoles. When such tadpoles remained longer in the foam nest, their ability to generate foam declined. Individual recently hatched tadpoles did not make foam out of water but did absorb water from wetter substrates. Later stage tadpoles of L. fuscus survived well out of water for at least six days but lost water gradually to the substrate (the drier, the faster). The dendrobatid Mannophryne trinitatis showed similar out of water survival to L. fuscus, but the leptodactylid Physalaemus pustulosus was much more limited, and the bufonid Bufo beebei had very little out of water survival ability. Tadpoles of L. fuscus lost water to the substrate proportionately more from the gut than from other organs, suggesting some regulatory capacity. Recently hatched tadpoles of L. fuscus showed better water retention when in groups in foam than when single on a damp substrate.

The Jambato Toad, Atelopus ignescens, is endemic to montane forests, inter-Andean valleys, and paramos in Ecuador. Although formerly abundant and widely distributed, the species has not been recorded in nature since 1988. To determine its population status, data from intensive surveys in 1999–2001 are compared with those from 1967 and 1981. Presence-absence data from several localities also are reported. Temperature and precipitation between 1891 and 1999 were analyzed to determine whether these correlate with population trends. Atelopus ignescens was abundant in 1967 at Paramo de Guamaní (47 individuals recorded in 120 pers/min) and in 1981 at Paramo del Antisana (up to 0.75 individuals/m²). In the 1999–2001 surveys, A. ignescens was absent despite considerably higher survey efforts. The presence-absence data at several localities also indicate a dramatic decline. Before 1988, A. ignescens was present during 64% of the visits to sites throughout its range. After 1988, A. ignescens was absent at all sites. The results strongly suggest that A. ignescens is extinct. Climatic data show that 1987, the year previous to the last record of A. ignescens, was particularly warm and dry. The reasons for the decline in pristine areas remain unclear, although the available information suggests that a combination of factors such as pathogens and unusual weather conditions may have played an important role.

I investigated the potential role of intra- and interspecific competition for food in Midland Watersnakes (Nerodia sipedon pleuralis) and Diamond-Backed Watersnakes (Nerodia rhombifer rhombifer) during the summers of 1999 and 2000. Snakes offered prey (juvenile spotted bass, Micropterus punctulatus) at low densities (five fish/enclosure/week) had significantly lower proportional changes in mass than snakes offered prey at high densities (10 fish/enclosure/week). However, differences in mass changes of N. sipedon were not significant at constant relative densities of prey to snakes. Nerodia sipedon and N. rhombifer that were offered 10 fish per week and tested individually had significantly higher mass changes than snakes tested in intraspecific pairs. For snakes maintained in interspecific pairs and offered 10 fish per week, N. sipedon had higher mass changes than N. rhombifer, although the difference was not significant. I lab-tested the potential for exploitation as a mechanism of competition between N. sipedon and N. rhombifer by comparing rates of gastric breakdown after feeding snakes a goldfish (Carassius auratus), forcing regurgitation at six, 12, and 18 h after ingestion, and comparing ash-free dry masses (AFDMs) of the digested fish. Relatively higher AFDMs of digested fish were obtained from N. sipedon than from N. rhombifer at six and 12 hours after ingestion. Thus, the former species exhibited a faster rate of gastric breakdown than the latter. These differences in competitive abilities may potentially contribute to the higher abundance of N. sipedon than N. rhombifer in the upper Pascagoula River system of southeastern Mississippi.

Sexual differences in maximum adult size occur commonly in frogs. We examined pre- and postmaturational growth of male and female Crinia georgiana and showed that sexual size dimorphism (SSD) of adults does not occur in this species. An experimental investigation of prematurational growth demonstrated that males averaged larger at maturation than females but that the sexes did not differ in the range of sizes at maturity. All individuals reached maturity by 14 months of age regardless of body size or sex, suggesting an age threshold to maturity of approximately one year in this species. In addition, C. georgiana have an unusually wide range of adult body sizes compared to other species and sexual differences in adult body size distributions. Thus, the lack of SSD in this species occurs in spite of sexual differences in growth rates. We hypothesize that sexual selection may be one of several mechanisms behind the lack of SSD and unusual body size variation in this species.

Although Upper Respiratory Tract Disease (URTD) has been recognized as a potentially serious problem threatening the viability of gopher tortoises, little is known about the impact of this disease on tortoise populations in the wild, and some researchers regard the disease as relatively benign. We monitored the impact of URTD on gopher tortoises at the Kennedy Space Center, Florida, and found a striking increase in the proportion of tortoises showing signs of URTD between 1995–2000. We also documented a sudden increase in the number of tortoises found dead at the site, starting in 1998 and continuing through 2001. Based on condition and position of dead tortoises, we strongly suspect that URTD was the cause of death. Sex ratios and body sizes of tortoises found dead were not distinguishable from samples of living tortoises, indicating that mortality was not confined to a single gender or age class. Combined with recent reports of large-scale mortality of tortoises from other sites in Florida, we suggest that URTD is not benign but may instead have a substantial impact on tortoise populations. If so, the “protected lands paradigm” that many resource managers rely on to conserve tortoise populations may be violated, suggesting that more active management measures are needed.

The Timber Rattlesnake (Crotalus horridus) is beset by a variety of conservation problems, including habitat loss and persecution. Effective management plans require an understanding of rangewide population structure and intraspecific evolutionary subdivisions. Northern and southern populations have been recognized as distinct subspecies, but this classification remains controversial. A proposed alternative arrangement recognizes southern, northern, and western morphotypes. To resolve intraspecific partitions, we examined a 319 base-pair (bp) fragment of mtDNA cytochrome b in 123 specimens of C. horridus. Neighbor-joining and parsimony analyses reveal a shallow gene genealogy (d_max = 0.024) and sharing of haplotypes among putative subspecies. Analysis of molecular variance demonstrates that traditional subspecific divisions explain only 3.5% of variation, whereas the alternative geographic classification (southern, northern, and western regions) explains 18.6% of genetic variation. The superior performance of the regional grouping can be attributed to an east-west phylogeographic partitioning at the Appalachian and Allegheny Mountain ranges, which were probably uninhabitable at higher elevations during glacial intervals. Distribution of haplotypes and climatic data suggest that a radiation into more northern areas occurred after the most recent (Wisconsinan) glaciation. Hence, the mtDNA data indicate distinct population segments across the range of C. horridus but do not show evolutionary separations that would support subspecific designations.

Snakes usually exhibit seasonal variations in movement patterns, home-range size and habitat use. This study evaluates the seasonal variation in movement rates, home-range size, habitat use, and microhabitat use by male Lataste's Vipers (Vipera latastei) in northern Portugal using radio-telemetry. Estimates of movement rate revealed short movements (5.4 m/day) and small home range size (0.24 ha) throughout the year, except in September when there was an increase in both movement rates (21.5 m/day) and home-range size (1.52 ha). Male vipers used different habitats and microhabitats during the year: forested areas for hibernation, open forest with bushes for foraging, and in the proximity of water in the summer.

Phylogenetic relationships among eight Brazilian genera of the lizard family Gymnophthalmidae were analyzed using mitochondrial DNA restriction-site data. The intergeneric relationships inferred from a cladistic analysis of 32 restriction sites were widely congruent with a recent phylogenetic analysis based on morphology. Assuming a molecular clock of 2% MY, these gymnophthalmid lizards may have diverged from a common ancestor some 7–8 MYA. The monophyly of the five eyelid-less microteiid genera from the Rio São Francisco Quaternary sand dunes was also supported by mitochondrial data, and the time estimated for this radiation was about 2–3 MYA. The mtDNA data also suggest that the unisexual population of Gymnophthalmus underwoodi from Roraima is not originated by hybridization between its two closely related sympatric bisexual species Gymnophthalmus leucomystax and Gymnopohthalmus vanzoi, in accordance with previous biochemical and karyotypic data.

Survival of adult Desert Tortoises (Gopherus agassizii) appears related to site-specific variation in precipitation and productivity of annual plants. We studied adult tortoise survival rates at two closely situated, but physiographically different, sites in the eastern Mojave Desert over a nine-year period (spring 1992 to spring 2001). Survival rates were initially derived from population surveys conducted over a three-year period and by radio-telemetry monitoring over a seven-year period beginning in 1994. After a period of initial stability, survival rates on the two sites diverged over the study period, and seven-year survival rates estimated from radio-telemetry monitoring were 0.900 and 0.269, respectively. A die-off in 1996 on the latter site appears to have been triggered by a period of drought, which began in the summer of 1995, coupled with a failure of annual vegetation production in 1996. Depressed survival rates on this site were associated with drought conditions during three of four years. Although the decline had the appearance of an epizootic, there were no clinical signs of disease. Relatively short-term drought, combined with little or no annual biomass, appears to have caused severe reductions in tortoise survival. If periods of drought-induced low survival are common over relatively small areas, then source-sink population dynamics may be an important factor determining tortoise population densities.

We investigated beach selection of nesting Pig-Nosed Turtles (Carettochelys insculpta) along a 63-km stretch of river for two years. We found 221 nests on 82 nesting beaches and identified 171 potential nesting beaches based on previously published criteria. Beaches with nests had a greater substrate moisture content and corresponding higher cohesive sand line (hereafter CSL) than beaches without nests. Beaches with nests also had a higher CSL than beaches with only crawls. Beach temperatures increased with a seasonal increase in air temperatures and were influenced by aspect and total angle of solar exposure. Turtles did not select beaches that were hotter or cooler, on average, than what was available, indicating that turtles were not manipulating offspring sex through choice of nesting beach.

Observed clutch frequency (OCF) and estimated clutch frequency (ECF) values were determined for the Green Seaturtle (Chelonia mydas) population that nests at Colola beach, Michoacán, México. Mean OCF and ECF values were 2.5 and 3.1, respectively. The use of the ECF value herein reported to estimate annual number of black turtle nesting females at this rookery decreased by approximately 20% previous population estimates based on OCF values.

At Conchas Lake State Park, San Miguel County, New Mexico, four allozymic variants of parthenogenetic Cnemidophorus tesselatus pattern class C and three allozymic variants of C. tesselatus D are syntopic with one gonochoristic and two parthenogenetic congeners. Our study of 14 individuals revealed that C. tesselatus C and D from this site are histoincompatible with both their maternal, Cnemidophorus tigris marmoratus, and paternal, Cnemidophorus gularis septemvittatus, progenitors. Evidence of skin histocompatibility between these combinations of C. tesselatus pattern class C and D lizards supports the hypothesis of a single hybrid origin for representatives of this species at the study site.

The omnivorous acrodont lizard Leiolepis belliana was shown experimentally to respond more strongly to chemical cues from prey and plant food than from control stimuli, as indicated by tongue-flicking and biting responses. These results extend previous findings that prey and plant chemical discrimination is widespread among omnivorous iguanians.

A recently described taxon of the snake genus Liophis (Liophis miliaris intermedius Henle and Ehrl 1991), is actually Liophis reginae.

We studied the ecology of a population of the mountain knob-scaled lizard, Xenosaurus grandis agrenon, from Oaxaca, México. Males and females did not differ in body size (SVL), but males did have larger heads and hind limbs than females. Mean litter size was 3.2. Sex ratio did not differ from 1:1. All lizards were found associated with crevices. The size of the crevice (thickness and depth) increased with lizard SVL. Mean body temperature was 25.6°C. Body temperature was related to air and substrate temperature. Body temperature was influenced by the amount of cover, and the lizard's body position in its crevice but not by sex, month, vegetation type, or any crevice characteristics. We compare the ecology of this population to that of other Xenosaurus.

Three “identical” haploid genomes (N = 22; 10M 12m) comprise the 3n = 66 (30M 36m) karyotype in the parthenogenetic gymnophthalmid lizard Leposoma percarinatum from Brazil. A hybridization event between a bisexual and a diploid unisexual species might explain the origin of L. percarinatum.

Temperature-dependent sex-determination has been reported for all extant crocodilians. We present information about incubation temperature effects on incubation period, sex ratio, hatching success, and hatchling survivorship during the first year of life for Caiman latirostris. Incubation period was negatively related to temperature. Sex of hatchlings were related to incubation temperature. Only females were produced at 29°C and 31°C, only males were produced at 33°C, and both males and females hatched at 34.5°C. Hatching success and survivorship were unaffected by incubation temperature.

The three species of chameleons inhabiting the primary forest on the western slope of Mount Kupe, Cameroon, Chamaeleo montium, Chamaeleo pfefferi, and Chamaeleo quadricornis, are compared with respect to elevational distribution, diet, and body size. Chameleo montium is restricted to lower elevations and markedly separated in elevational distribution from its congeners, which are exclusively found in the submontane forest. The three species prey almost entirely on arthropods, mostly coleopterans, heteropterans, hymenopterans, dipterans, and spiders; niche breadth values that incorpate prey availability are high and suggest opportunistic feeding. Niche overlaps are high with respect to prey type, but the smallest species, C. pfefferi, differs significantly from its congeners in terms of prey volume. Body size difference is largest between the two syntopic species, C. pfefferi and C. quadricornis, and identically low to the allotopic C. montium. The results on dietary segregation and morphological similarity are in accordance with competition limiting elevational distributions of the chameleons on Mount Kupe.

The food habits of the snake Psammophis phillipsi were studied in the rain-forest region of southeastern Nigeria, where this is the most common snake species of the area. A total of 120 prey items were recorded from 327 specimens (73 juveniles; 55 gravid females); many gravid females contained prey. Lizards (mainly Agama agama and Mabuya skinks) were the most common prey type for adult snakes, both gravid and nongravid, and for subadults as well; small mammals were the second most common prey type for all snake categories. Insects and small snakes (including conspecifics) were occasionally consumed. Diet composition did not differ significantly between gravid and nongravid specimens, but gravid specimens more frequently contained small mammals and fewer lizards. Ontogenetic dietary change was relatively minor. Prey and predator mass were significantly related in both adults and subadults.

Reduced aggression toward territorial neighbors relative to strangers, the dear enemy phenomenon, is a widespread occurrence in many taxa, presumably because a stranger represents more of a threat to a resident than a neighbor. We recorded the response of 12 adult, nonreproductive, female Crotaphytus collaris residents to tethered neighbors or size-matched strangers and found no significant difference between responses to neighbors and strangers. Given that the dear enemy phenomenon is advantageous only to highly territorial individuals that stand to lose a great deal to a stranger, but not a neighbor, and that costs of territoriality may change with the reproductive cycle, we argue that there are no favorable conditions for the dear enemy phenomenon to evolve in this population of female collared lizards.

In 1993, the amphibian fauna of Las Tablas, Costa Rica, began to decline, and by 1998 approximately 50% of the species formerly present could no longer be found. Three years later, at the Reserva Forestal Fortuna, in western Panama, a site approximately 75 km east southeast of Las Tablas, KRL encountered a mass die-off of amphibians and a subsequent decline in abundance and species richness. The epidemiological features of the anuran population declines and die-offs at both sites were similar, suggesting a similar cause. Herein we document the presence of the fungus, Batrachochytrium dendrobatidis, in dead and dying wild frogs collected at Las Tablas just prior to population declines of several anuran species.

Previous studies have demonstrated the accumulation of arsenic, cadmium, selenium, strontium, and vanadium in livers of Southern Watersnakes fed fish from a coal-ash contaminated site. Our study is the first to investigate effects of trace element accumulation on cytology of snake liver. Snakes were born in the laboratory and raised for one or two years on diets consisting of varying proportions of contaminated fish. The majority (71%) of snakes fed contaminated prey did not exhibit any differences in liver histology when compared to control snakes fed an uncontaminated diet. In the remaining contaminant-exposed snakes, some aberrations were noted. The most prevalent pathology involved the proliferation of collagen fibers that resulted in narrowing or occlusion of sinusoids and increasing the mass of the intersinsuoidal parenychma. Fibrosis of the liver as a result of chronic injury has been reported previously in reptiles, but this is the first report that links such tissue damage to dietary contamination.