We studied activity and habitat use by the teiid lizard Cnemidophorus nativo in Parque Estadual Paulo César Vinha (PEPCV), an area located near the southernmost limit of the species distribution – the Restinga of Setiba in the state of Espírito Santo, southeastern Brazil. Activity of C. nativo was estimated by hourly transects from 07:00 to 18:00 h searching for lizards. Lizard activity was expressed by the frequency of active individuals in each hour interval. Microhabitat use by C. nativo was measured along 20 one-hour transects of lizard search in different areas of PEPCV. For every lizard seen we recorded the microhabitat it was using at the moment of first sight. Cnemidophorus nativo (N = 73) was active mainly from 07:00–14:00 h with a peak of activity from 09:00–11:00 h, when approximately 80% of the individuals were observed. The main microhabitats used by C. nativo at PEPCV were bare sand and vegetation edges (nearly 70% of the individuals recorded). No significant difference was found in habitat use between adults and juveniles. We concluded that Cnemidophorus nativo from Setiba has an activity concentrated in the morning, with activity decreasing when air temperature in the habitat is near the peak, and that its preferred microhabitats in the area are open sand or vegetation edges.

Advertisement, territorial, and distress calls of Hypsiboas exastis, a species of the Hypisboas faber group, are described for the first time. Acoustic records were obtained of one specimen found at the Municipality of Uruçuca, state of Bahia, Brazilian eastern cost. We compared the advertisement calls of H. exastis with those of H. lundii and H. pardalis (the closest related species) and suggested a closer similarity with H. lundii.

We describe two new species of lizards of the genus Liolaemus belonging to the chiliensis group, one found in southwestern Catamarca, and the other in central western Argentina, in Mendoza, San Juan and Catamarca provinces. The species from southwestern Catamarca has morphological characteristics that may relate it to the species of the capillitas group, a northern clade of the elongatus group, whereas the other species has characters that relate it to the southern clade of the elongatus group. Both species exhibit diagnoistic character states in their maximum snout-vent length, squamation, and dorsal and ventral colors, which differentiate them from the other species of the chiliensis group.

Sexual dimorphism, reproduction and diet are described for Stenocercus caducus from semideciduous forest, in Mato Grosso do Sul state, Central Brazil. Lizards are collected in pitfall traps from December 2000, to December 2001. Sexual dimorphism in S. caducus is apparent, mainly in coloration; although females reach a larger SVL than males. A wide variety of arthropods are fed by S. caducus, with ants and termites numerically, and orthopterans and beetles volumetrically the most common prey items. Ontogenetic differences in diet were noted for S. caducus, with juveniles feeding on lesser prey types and smaller sized prey than adults. The reproduction was seasonal, concentrated in the rainy season, with deposition of more than one clutch per season.

Currently there are 12 recognized species in the genus Phyllodytes; however, advertisement calls are known for only three species. Herein, we describe the advertisement call of Phyllodytes edelmoi, from males recorded at the type-locality, in remnants of Atlantic Rain Forest in northeastern Brazil. The advertisement call duration is 4.28–5.73 s and it is composed of 22–29 pulsed notes. Each note has 6–32 pulses. The dominant frequency along the call ranges from 1.49–3.32 kHz. The call is compared with available call descriptions of P. kautskyi, P. luteolus, and P. melanomystax. Despite clear differences among their advertisement calls, apparently the calls of P. edelmoi and P. luteolus share a few similarities. Phylogenetic relationships in the genus Phyllodytes are unresolved and descriptions of vocalizations of additional Phyllodytes species could help to decipher these relationships.

It is plausible that introduced species in the beginning of an invasion would be subjected to selection pressure to disperse rapidly so as to access unexploited habitats, but be subjected to selection pressure for more sedentary behavior once the available habitat was fully colonized. Using a mix of previously-published and new data from the introduced Brown Treesnake (Boiga irregularis) population on Guam we evaluated this scenario and found that: 1) Brown Treesnakes accessed a food bonanza when colonizing Guam, and then depleted it; 2) during the irruption, high-dispersing Brown Treesnakes most-likely benefitted by accessing undepleted or less-depleted food areas; and 3) after the irruption, high-dispersing Brown Treesnakes probably wasted effort through superfluous movement, and Brown Treesnake activity areas on Guam decreased in size in the 1990s, possibly in response to selection pressure for reducing superfluous movement. Nonetheless, 4) confined Brown Treesnakes had better fitness measures in 2004–2006 than snakes free to disperse, suggesting that selection pressure to reduce movements was ongoing. We conclude that selection in the post-irruption period promoted reduced dispersal and we observed appropriate change over generations, but we do not know the extent to which the observed changes reflect genotypic or phenotypic responses.

Previous studies have shown that snakes can use groundborne vibrations for localizing prey, and some have proposed that such vibrations provide important cues for cottonmouth snakes while foraging on fish that fall from island bird rookeries. The latter hypothesis was tested by using fish and fish models to study the behavioral response of insular Agkistrodon piscivorus conanti to groundborne vibrations and olfactory cues. Diving and wading birds that nest on Seahorse Key, a small island adjacent to the northern Florida peninsula in the Gulf of Mexico, regularly drop fish in the vicinity of resident A. piscivorus during the colonial nesting period. Here we report that presentation of an equivalent groundborne vibration, without associated chemosensory or visual stimuli, failed to induce overt foraging behavior in these snakes. However, presentation of a fish-based olfactory stimulus, without associated groundborne vibration or motion, triggered a foraging response in A. piscivorus. Snakes from two study sites reacted differently to the olfactory stimulus; those from the site with less ground cover, more rats, and fewer snakes exhibited a weaker foraging response.

Insular snake populations show bimodal size distributions with giants evolving on islands with large prey size and dwarfs on islands with small prey size. However, there is virtually no published study that examined growth trajectories of wild individual snakes to test whether giant and dwarf populations of a species differ in their growth rates and life spans. In order to address this issue, we compared the growth history of individually marked snakes in three insular and one mainland populations of Elaphe quadrivirgata. Our long-term field study, which started in 1982, suggests that gigantic snakes on Tadanae-jima, the Izu islands, take twice as long (30 to 40 years) to attain maximum snout-vent length as snakes from two non-gigantic insular populations. Our study also clearly demonstrated that snake gigantism is achieved by continuous growth throughout ontogeny rather than extensive growth early in their life. Contrary to expectations, young snakes from the gigantic populations grew more slowly than those of the other populations. We discuss potential proximate mechanisms that cause these different growth trajectories, particularly focusing on the exploitation of large sized avian eggs by older aged snakes, which would be a key factor enabling gigantism of the snake.

Island populations of the Lake Erie watersnake (Nerodia sipedon insularum) have experienced a dramatic environmental change in the form of a new abundant prey species, the round goby (Neogobius melanostomus). Effects of this biotic change on watersnake reproductive characteristics were tested by comparing offspring size and the relationship between female size and offspring number before and after the round goby invasion. Offspring number, but not offspring size, increased as a consequence of watersnake diet change. In addition, female size explained a greater proportion of the variation in offspring number following the round goby invasion (60% vs. 25%). The combined effects of increased female size and offspring number are projected to result in an increase in watersnake fecundity exceeding 25% and may be stimulating watersnake population growth since the round goby invasion. The rapidity of watersnake diet change and consequent change in fecundity is consistent with the maximization hypothesis of life history theory and suggests that watersnake life history may have been more strongly limited by resource availability prior to the round goby invasion.

Rattle loss in the Isla Santa Catalina (Baja California Sur, México) rattlesnake, Crotalus catalinensis, was hypothesized to be a stealth adaptation for hunting for birds within the vegetation. Recently, however, it was shown that birds are rarely captured by C. catalinensis, while a semi-arboreal mouse is very important in its diet. It was thus suggested that the loss of the rattle could be a stealth adaptation for hunting for mice within the vegetation. But both these hypotheses imply a high degree of arboreality in C. catalinensis, and there is no detailed study on microhabitat use in this species. Here we use field data recently obtained (2005 to 2008) to test the hypothesis of a high degree of arboreality in C. catalinensis. During nine visits to Isla Santa Catalina we searched for snakes in suitable habitats. Of 92 observations in which the snakes were exposed, in seven occasions (7.6%) they were on the vegetation. There was no difference between sexes or between young and adult snakes in the frequency of use of vegetation. Thus, C. catalinensis is a primarily terrestrial rattlesnake which uses the vegetation only occasionally, similar to its sister species Crotalus ruber. Results of a previous phase of our studies at Isla Santa Catalina are similar to those presented herein. These results make the hypothesis of the loss of the rattle as a stealth adaptation for hunting on the vegetation very unlikely, since such a low frequency of use of vegetation may not function as a selective agent that could lead to an adaptive loss of the rattle.

Although Bothrops insularis is critically endangered, there is no estimate of its population size based on field quantifications. Here we provide the first estimate of its population size based on plot surveys conducted at the Queimada Grande Island. We distributed 26 quadrat plots regularly in a trail that crosses the island. Plots were sampled twice in 2002. Of the 26 plots we sampled, 21 were located in forests and five in grassy areas. For the first survey, mean estimates of population size for plots located in forests and grassy areas were 2134.3 and 224.0 snakes, and the Percentage Relative Precision for these estimates were 38.6% and 277.6%, respectively. For the second survey, no snakes were found in grassy areas, whereas the mean estimate of population size for plots located in forests was 1304.3 snakes and the Percentage Relative Precision for these estimates was 93.7%. Although suffering from relatively low precision, our best estimate of population size in B. insularis is around the lower end of the guesses found in the literature (2000–4000 individuals for the entire island). Furthermore, based on encounter rates obtained in a non-systematic way in the last 12 years, we have the impression that the density of B. insularis decreased in this period and we have evidence for the illegal removal of snakes from the island in the last few years. Our results suggest the urgent need of enforcement to restrain the illegal removal of snakes from the island and of a monitoring program to track future changes in the population size of B. insularis.

Florida cottonmouth snakes (Agkistrodon piscivorus conanti) inhabit insular as well as mainland habitat, and they occur in particularly large numbers on some of the Gulf coast islands of Florida. The success of this species on islands is attributable, in part, to a broad trophic niche that encompasses many prey items including carrion. Numerous cottonmouths living on the island of Seahorse Key consume primarily dead fish that are dropped from colonial nesting bird rookeries, but they also prey on rats (Rattus rattus) that are invasive fauna on the island. While alternative prey items (e.g. lizards) are available to newborn snakes, smaller individuals also scavenge for fish carrion at early ages. Field observations indicate there is social structure during foraging events that involve multiple snakes. Occasionally, insular cottonmouths scavenge for intertidal carrion and detritus that washes onto beaches. Numerous and diverse objects of appropriate size, shape, and odor are ingested by foraging snakes, including masses of marine algae that bear fish odors. The intensive scavenging behaviors of cottonmouths appear to reflect behavioral and physiological specializations that have evolved in response to insular resource limitations. Two important pathways by which allochthonous marine productivity enters the terrestrial food web to support these insular cottonmouths are (1) colonial bird rookeries and (2) shore drift of carrion and detritus. The importance of the bird rookeries as a source of marine fish is reflected in the observation that far lower numbers of cottonmouths occur on islands that lack a bird colony. We have no evidence that the insular cottonmouths feed on the colonial nesting birds, but they consume smaller passerine species.