Males and females of the oriental garden lizard (Calotes versicolor) from a population in Hainan, southern China, differed in head size at hatching: males had larger heads than females. This dimorphism was slightly more pronounced in adults than in hatchlings. Hatchlings had larger heads but shorter tails relative to snout–vent length (SVL) than subadults and adults. When SVL was held constant, tail length of subadults and adults of the same sex was similar. Adult lizards were not sexually dimorphic in body size (SVL), but males possessed longer tails than females at the same SVL throughout their size range. The smallest and largest reproductive females in our sample were 78.9 and 103.8 mm SVL, respectively. Females in our laboratory (Hangzhou, eastern China) laid multiple clutches from April to June. Clutch size, clutch mass, and egg mass varied from 3 to 14 (mean = 9.0) eggs, 1.58 to 6.47 (mean = 4.65) g, and 0.45 to 0.61 (mean = 0.52) g, respectively. Clutch size and clutch mass were both positively correlated with female SVL. Egg mass was not correlated with female SVL even when clutch size was held constant using a partial correlation analysis. Clutch size was not correlated with female condition when female SVL was held constant. Egg length, egg width, and clutch size were not correlated with each other when the remaining variable was held constant. Egg mass was not correlated with clutch size when female SVL was kept constant. Larger-sized C. versicolor females increased reproductive output primarily through production of more eggs (and hence heavier clutches).

Many antipredator behaviors function by hindering the ability of a predator to catch or consume prey once they are encountered. However, prey may also reduce predation risks by detecting predators before an encounter occurs. We tested the ability of the desert iguana (Dipsosaurus dorsalis) to detect and identify snake predators via chemoreception. Desert iguanas were exposed to chemicals from two sympatric snake species. The California kingsnake (Lampropeltis getula californiae), a species known to feed on lizards, was used as the predator stimulus, whereas the western shovel-nosed snake (Chionactis occipitalis), which feeds only on arthropods, served as a control for a general response to snake chemicals. Lizards were placed in terraria that previously housed live snakes or had been treated with distilled water or a pungent control. Overall tongue extrusion frequency and number of tongue extrusions prior to movement increased in response to chemicals from the California kingsnake but not in response to the western shovel-nosed snake. In addition, desert iguanas exhibited unusual slowness of movement and adopted a distinctive body posture in response to the predator stimulus. These results demonstrate that desert iguanas can detect chemical deposits from snakes and can discriminate between a snake species that feeds on lizards and one that poses no threat. In addition, the resulting low posture and slow movement may facilitate crypsis as the lizards attempt to gain information regarding the predator. Desert iguanas are herbivorous lizards and may use chemical cues to detect and avoid snake predators while foraging or when entering burrows.

The dramatic amphibian population declines reported worldwide likely have important effects on their predators. In the Sierra Nevada, where amphibian declines are well documented and some are closely tied to the introduction of nonnative trout, the mountain garter snake, Thamnophis elegans elegans, preys predominately on amphibians. We surveyed 2103 high-elevation lakes in the Sierra Nevada, quantified the distributional relationship between the mountain garter snake and anuran amphibians (Pseudacris regilla, Rana muscosa, and Bufo spp.) and used this information to evaluate the possibility that amphibian declines lead to declines of garter snakes. We observed a strong association between amphibian presence and garter snake presence. The probability of finding snakes in lakes with amphibians was 30 times greater than in lakes without amphibians. Lakes with snakes had higher numbers of amphibians within 1 km (mean = 4018.8) than did lakes without snakes (mean = 642.1). On a landscape scale, in Kings Canyon National Park (where 40% of larger lakes contain nonnative trout) amphibians were found in 52% of lakes, and 62 garter snakes were found in 33 of the 1059 lakes surveyed. In contrast, in the John Muir Wilderness (JMW; where 80% of larger lakes contain nonnative trout), amphibians were found in 19% of lakes, and no snakes were found in any of the 1044 lakes surveyed. Based on these data, we suggest that the introduction of nonnative trout has led not only to the decline of amphibians but also to the decline of garter snakes. This study supports the hypothesis that the presence of amphibians is a prerequisite for garter snake persistence in high-elevation portions of the Sierra Nevada and that the introduction of trout into an ecosystem can have serious effects, not just on their prey but also on other predators in the ecosystem.

Collared lizards, Crotaphytus collaris, live in isolated populations on Missouri glades. Anecdotal observations suggest that another lizard species, Sceloporus undulatus, is rare on glades where C. collaris is present. Possible causes of scarcity of S. undulatus in the presence of C. collaris include competition, predation, and unsuitable thermal conditions. We characterized thermal biology and habitat partitioning in these two species by measuring body and air temperatures, and microhabitat use, at three glades. Sceloporus undulatus maintains lower body temperatures than C. collaris and shifts from open rock perches to shady tree perches during the middle of its activity season. Crotaphytus collaris microhabitats are rockier and more open than those of S. undulatus, which tend to have more branches, leaves, and trees nearby. These data indicate that areas of glades hot enough for use by C. collaris are too hot for S. undulatus. Although we cannot rule out competition or predation, constraints of the thermal environment may be an important factor in the apparent scarcity of S. undulatus on glades.

Adult Triturus newts show spatial and temporal variation in sex ratio at the aquatic breeding site, to the extent that contrasting scenarios on the evolution of mating systems appear to be supported. I collected data for the five western European species (Triturus alpestris, Triturus cristatus, Triturus helveticus, Triturus marmoratus, and Triturus vulgaris) over 500 ponds and 27 yr in two areas in France, to test the hypothesis that the phenology of pond presence is independent of gender. Approximately equal numbers of males and females were found. However, in T. marmoratus males outnumbered females, which could be explained by a proportion of females skipping annual breeding opportunities. In the hybrid T. cristatus × T. marmoratus, females were twice as numerous as males, in accordance with Haldane's rule. A trend was observed for a male-biased sex ratio at the start of the aquatic season (late winter–early spring) and for a female bias toward the end of the aquatic season (early summer), suggesting that males mostly arrive and leave the breeding sites ahead of the females. The data do not support evolutionary scenarios selecting for the early breeding of female T. vulgaris.

We studied the reproductive characteristics of the spiny lizards, Sceloporus horridus and Sceloporus spinosus (Phrynosomatidae). The specimens (N = 102) of S. horridus came from the state of Morelos and Guerrero, and individuals of S. spinosus (N = 87) came from Puebla, México. Male S. horridus exhibited a peak of reproductive activity during early spring and early summer and male S. spinosus during spring and autumn. Females of both species showed a reproductive peak during the summer. Vitellogenesis of S. horridus began in late March and of S. spinosus in late January, and ovulation in both species occurred during spring and early summer. Mean snout–vent length (SVL) of sexually mature females (based on the largest 50%) was higher in S. spinosus (x̄ ± SE = 98.6 ± 1.85) than in S. horridus (91.4 ± 1.32, P < 0.05). Mean clutch size (vitellogenic follicles oviductal eggs) for S. spinosus was higher (18.5 ± 1.5, N = 18) than for S. horridus (14.8 ± 0.91, N = 30, P < 0.05). There was no significant correlation between snout–vent length of females and clutch size of S. spinosus (r = 0.51, P > 0.05) or S. horridus (r = 0.06, P > 0.05).

The materials and energy invested in each egg by most oviparous reptiles represent the majority of total parental investment in offspring. For Natator depressus from eastern Queensland, Australia, the shell contributed approximately 5%, the albumin 45%, and the yolk 50% to the total egg mass (74 g). Water averaged 79% of the total egg mass. Lipids averaged 29% of the total dry mass of the egg and 35% of the yolk dry mass. Eggs of N. depressus contained a high proportion of yolk lipids and water, with greater “parental investment” than those of nonmarine turtles. Approximately 26–27% of lipids in the egg was used for embryogenesis, whereas 73–74% was transferred to the entire hatchling. Initial yolk lipid in the residual yolk was approximately 30–37% but varied with incubation environment. Residual yolk lipids are likely to be used as the immediate energy source for the hatchlings.

A new species of Rhampholeon from the montane and submontane escarpment forests of the Udzungwa Mountains is described. This pigmy chameleon has a maximum total length of 64 mm and bears a close morphological resemblance to Rhampholeon uluguruensis, differing mainly by possessing finer cranial scalation and more thornlike hemipenal papillae arranged in two proximal rows of four (occasionally five) and two followed by a single terminal row of four (occasionally five) papillae. The only known populations of this species are found in Udzungwa escarpement forests between 1200 and 2000 m a.s.l. The zoogeography and systematics of related species of the genus Rhampholeon in the Eastern Arc Mountains of Tanzania and Malawi are reviewed and an updated key to the Genus Rhampholeon is presented.

Because of the deleterious effects of predation by nonnative brown treesnakes (Boiga irregularis) on of native vertebrates on the island of Guam, efforts have been focused on developing effective means of controlling B. irregularis and preventing its spread to neighboring islands. Past laboratory attempts to evaluate potential baits for trapping B. irregularis have often not agreed with field results. Here we present a new laboratory situation for studying effects of various baits on prey finding ability of B. irregularis that uses trailing latencies as a measure of bait efficacy. Our results show that B. irregularis will follow trails made by rodent blood, whole rodent carcasses, and synthetic bait compounds. However, snakes followed trails made by rodent carcasses and blood at a significantly faster rate than those made by synthetic bait compounds. Further, the presence of a visual distracter cue significantly increased trailing latencies. Implications of these results for trapping efforts are discussed.

Human activities affect animal populations whenever animals and humans live in close proximity, but patterns of mortality in urban wildlife remain poorly known. We analyzed rates of injury and mortality of bluetongue lizards (Tiliqua scincoides) in Sydney, Australia, using a Wildlife Information and Rescue Service database that contained more than 2000 reported “rescues” of this species over a three-year period. Motor vehicles and dogs killed many adult lizards in springtime (the mating season) when adult males move about more frequently. Domestic cats killed mainly juvenile lizards, especially just after parturition in midsummer. Weather conditions affected rescue rates, presumably because lizards were more active on hot dry days. Habitat loss was the most important cause for lizard rescue in highly urbanized areas, whereas domestic pets were a major threat in outlying suburbs. Such datasets are subject to many biases but allow meaningful comparisons at some levels of analysis. The large datasets of wildlife rescue groups have considerable potential to illuminate the nature and frequency of interactions between humans and wildlife.

Selection of diurnal shelter sites varies significantly with season in the cane toad (Bufo marinus), and the aim of this paper is to determine how hydric and thermal conditions of shelter microhabitats changed with season and whether those changes explained seasonal differences in toad behavior. Body temperatures of cane toads were measured by telemetry, and dehydration rates and thermal conditions of shelter microhabitats were measured by using preserved toads as environmental probes. Live toads and preserved toad models were monitored monthly over a 18-month period. Laboratory experiments showed that toad models dehydrated at the same rate as live toads. In the field, dehydration rates varied significantly between seasons and shelter microhabitats, but dehydration rates were always significantly less in shelters compared to a nonshelter control. Daily average body temperature of toads was 16–30°C, and it changed seasonally in proportion to model temperature. Diurnal model temperature was significantly lower in shelters compared to the nonshelter control, but there were significant seasonal differences between shelter sites. It appears that access to suitable diurnal shelter sites is essential for survival of cane toads outside the wet season and that seasonal changes in environmental conditions influence shelter microhabitat selection.

We conducted a field study to evaluate whether coverboards are as effective for sampling terrestrial salamanders as searching natural cover objects such as fallen logs and branches. At each of five sites in Jenkins County, Georgia, we paired a grid of 100 wooden coverboards (30.4 × 30.4 × 2 cm) placed 10 m apart with an adjacent grid containing only natural debris. Searches under coverboards detected most of the same species (Plethodon ocmulgee, Eurycea cirrigera, Eurycea quadridigitata, and Eurycea guttolineata) as found under natural cover (same four species plus Ambystoma opacum). However, salamanders were encountered at lower average rates under coverboards (0.8 salamanders per grid search) than under natural cover (2.3 salamanders per grid search), and this pattern was consistent across seasons. The number of salamanders encountered was more variable within coverboard grids than within grids of natural cover; mean encounter rates were equally variable among grids for the two techniques. For the most commonly encountered species (P. ocmulgee), individuals from coverboards were similar in size to those found under natural cover. There was no tendency for coverboards to accumulate more salamanders through time. Temperatures were more variable under coverboards than under natural cover.

We studied the reproductive cycle of Tropidurus torquatus in the Cerrado biome of central Brazil from October 1997 to September 1998. Females reached sexual maturity at about 65 mm snout–vent length (SVL), whereas males became sexually mature at 70 mm SVL. Females were reproductively active between August and February, although males contained spermatozoa in the epididymides year-round. Frequency of reproductive females was inversely correlated with precipitation and air humidity and positively correlated with day length. Reproductive activity of males was inversely correlated with air humidity and positively correlated with day length. Females laid six eggs on average and may have produced up to three clutches per reproductive season. With the advancement of the reproductive season, clutches tended to be smaller, whereas egg size remained constant. Fat body mass varied inversely with reproductive activity in both sexes, but females had significantly larger values than males. After an incubation period of approximately 5 months, young emerged at a SVL around 31 mm. Juveniles began to accumulate energy in fat bodies after reaching 47 mm SVL. The fat body cycle and the recruitment pattern of T. torquatus suggest that food resources are not limiting and that the length of the reproductive season is most likely constrained by the availability of microhabitats suitable for egg development.