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Animal personality can be defined as behavioral individual consistency across contexts and time, and sociability may facilitate it. Boldness and exploration can be considered as social conflictive behaviors and in lizards, social scent can either diminish or promote social conflicts. We studied boldness and exploration in Liolaemus albiceps Lobo and Laurent, 1995 and Liolaemus coeruleus Cei and Ortiz, 1983, and tested whether Liolaemus albiceps, a lesser aggressive species, presents higher individual consistency in a socially nonconflictive behavior, such as escape (boldness). We also expect Liolaemus coeruleus, a more aggressive species, to present higher individual consistency in exploration, which is socially more conflictive behavior. We exposed lizards to their own conspecifics and control scent treatments. We calculated the repeatability for boldness and exploration, analyzed their correlation, and tested for behavioral plasticity. Boldness and exploration were repeatable in Liolaemus albiceps at species level, with females showing highly repeatable boldness, and males, highly repeatable exploration. Liolaemus coeruleus exhibited no significant repeatability for either behavior. There was no correlation between these two behaviors, and both species showed plasticity. Liolaemus albiceps individuals were bolder and explored less under conspecific scents. Liolaemus coeruleus individuals explored less in presence of their own scents than novelty scents, and presented interindividual variation in plasticity. A peaceful lifestyle may favor behavioral consistency within individuals, whereas a more aggressive lifestyle may constrain within and among individual consistency in a chemical communication context. However, individual differences in plasticity could counterbalance this constraint. Key words: behavioral types, plasticity, repeatability, Squamata, Introduction Animal personality can be defined as those consistent individual differences in the same behavior across distinct contexts, situations, and times (Dall et al. 2004; Dingemanse et al. 2010; Reale [...]

Because temperature affects the growth, development, and survival of embryos, oviparous mothers should discriminate carefully among available nesting sites. We combined a radiotelemetric study of animal movements with a spatial mapping of environmental temperatures to test predictions about the nesting behavior of the eastern fence lizard (Sceloporus undulatus). Females made large excursions from their typical home ranges to construct nests in exposed substrates. These excursions appeared to be related solely to nesting because all females returned to forested habitat immediately afterward. On average, < 1% (range = 0-8%, n = 19) of the area used by a female during nesting was contained within the area used before and after nesting. The selection of nesting sites matched predictions based on laboratory studies of embryonic performance; specifically, females nested in extremely open habitat at a mean of 6 cm depth. Spatial mapping of soil temperatures revealed that temperatures of nesting areas exceeded those of areas typically used by females, indicating that females preferred to construct warm nests that speed embryonic growth and development. However, this behavior could reduce the survivorship of females because of the need to rapidly navigate unfamiliar and exposed terrain. Key words: artificial neural network; eastern fence lizard; microhabitat; nesting; reptiles; Sceloporus undulatus; temperature; thermoregulation.

Prey often exhibit reduced escape behavior on islands where predators are absent or scarce. Models of escape and refuge use predict that prey from populations having lower predation pressure have shortened flight initiation distance (FID; distance between a predator and a prey when escape begins), reduced distance fled and tendency to enter refuge, and shortened hiding time before emerging from refuge. By ourselves simulating approaching predators, we tested these predictions for two populations of the Balearic lizard, Podarcis lilfordi (Muller, 1927), on the islets of Rei (higher predation pressure) and Aire (lower) adjacent to Menorca. FID, distance fled, and hiding time were shorter and probability of entering refuge was lower on Aire than on Rei, confirming all predictions. All effect sizes were large, indicating major differences in antipredatory behavior between islets. These findings are consistent with data for other lizards on FID and limited data on distance fled and refuge entry. The effect of predation pressure on hiding time is a novel finding. Our results and those of previous studies suggest that relaxation of predation pressure leads to reduced natural selection for maintenance of antipredatory behavior at all stages of predator-prey interactions over a relatively short time span. Les proies ont souvent des comportements de fuite reduits sur les iles ou` les predateurs sont absents ou rares. Les modeles de fuite et d'utilisation des refuges predisent que les proies des populations qui connaissent des pressions de predation plus faibles ont une distance d'initiation de la fuite (FID; distance entre le predateur et la proie au debut de la fuite) plus courte, une distance de fuite et une tendance a entrer dans un refuge reduites et une periode de dissimulation plus courte avant de sortir du refuge. En simulant nous-memes l'approche d'un predateur, nous avons teste ces predictions chez deux populations du lezard des Baleares, Podarcis lilfordi (Muller, 1927), sur les ilots de Rei (pression de predation plus forte) et Aire (moins forte) adjacents a Minorque. La FID, la distance de fuite et la periode de dissimulation sont plus courtes et la probabilite d'entrer dans un refuge moindre sur Aire que sur Rei, ce qui confirme toutes les predictions. L'importance de tous les effets est grande, ce qui indique des differences majeures dans le comportement antipredateur entre les ilots. Ces resultats concordent avec les donnees de FID chez d'autres lezards et avec les donnees limitees disponibles sur la distance de fuite et l'utilisation des refuges. L'effet de la pression de predation sur la duree de la dissimulation est une nouvelle observation. Nos resultats et ceux d'etudes anterieures laissent croire que le relachement de la pression de predation mene a une reduction de la selection naturelle pour le maintien du comportement antipredateur a toutes les etapes des interactions predateur-proie sur une periode de temps relativement courte. [Traduit par la Redaction], Introduction Animals on islands are often subject to lower predation pressure than mainland populations, resulting in evolution of tameness, a reduction in escape behavior when confronted by people or predators [...]

Nonnative species introductions are becoming more common, but long-term consequences of the novel pressures imposed by invaders on native species remain poorly known. The red imported fire ant, Solenopsis invicta, is an invasive species with potential global impact. Comparison of lizards across the invasive range within the United States reveals novel antipredator strategies and altered morphologies that mitigate potentially lethal attack by these ants, within 70 years of their introduction. The likelihood that adult lizards will behaviorally respond to fire ant attack increases with time since invasion, but hatchlings exhibit high levels of antipredator behavior irrespective of their site of origin. Adults and hatchlings from sites invaded longer ago also have relatively longer hind limbs. This trait increases the effectiveness of behavioral strategies for removing ants and is likely an adaptive response to minimize envenomation during attack. The observed changes are not correlated with habitat, exposure to fire ants, or latitude, arguing against phenotypic plasticity and learning as causal mechanisms, and museum specimens show that morphological differences were not evident prior to fire ant invasion. These data contribute to our growing awareness that ecological invasions can prompt adaptive responses, altering the nature of interactions between invaders and the natives they contact. Key words: adaptation; behavior; fence lizard; fire ant; invasive species; morphology; predator; Sceloporus undulatus; Solenopsis invicta.

Species in which ambient temperatures directly determine offspring sex may be at particular risk as global climates change. Whether or not climate change affects sex ratio depends upon the effectiveness of buffering mechanisms that link ambient regimes to actual nest temperatures. For example, females may simply lay nests earlier in the season, or in more shaded areas, such that incubation thermal regimes are unchanged despite massive ambient fluctuation. Based on eight years of monitoring nests over a 10-year period in the field at an alpine site in southeastern Australia, we show that, even though lizards (Bassiana duperreyi, Scincidae) have adjusted both nest depth and seasonal timing of oviposition in response to rising ambient temperatures, they have been unable to compensate entirely for climate change. That inability stems from the fact that the seasonal progression of soil temperatures, and thus, the degree to which thermal regimes at the time of laying predict subsequent conditions during incubation, also has shifted with climate change. As a result, mean incubation temperatures in natural nests now have crossed the thermal threshold at which incubation temperature directly affects offspring sex in this population. Key words: Bassiana duperreyi; climate change; global warming; nesting behavior; phenology; temperature-dependent sex determination (TSD).

Ecologists increasingly recognize the ability of certain species to influence ecological processes by engineering the physical environment, but efforts to develop a predictive understanding of this phenomenon are in their early stages. While many believe that the landscape-scale effects of ecosystem engineers will be to increase habitat diversity and therefore the abundance and richness of other species, few generalities exist about the effects of engineering at the scale of the engineered patch. According to one hypothesis, activities that increase structural habitat complexity within engineered patches will have positive effects on the abundance or diversity of other organisms. Here I show that, by damaging trees and increasing their structural complexity, browsing elephants create refuges used by a common arboreal lizard, Observational surveys and a lizard transplant experiment revealed that lizards preferentially occupy trees with real or simulated elephant damage. A second experiment showed that lizards vacate trees when elephant-engineered refuges are removed. Furthermore, local lizard densities increased with (and may be constrained by) local densities of elephantdamaged trees. This facilitative effect of elephants upon lizards via patch-scale habitat modification runs contrary to previously documented negative effects of the entire ungulate guild on lizards at the landscape scale, suggesting that net indirect effects of large herbivores comprise opposing trophic and engineering interactions operating at different spatial scales. Such powerful megaherbivore-initiated interactions suggest that anthropogenic changes in largemammal densities will have important cascading consequences for ecological communities. Key words: allogenic ecosystem engineers; disturbance; geckos; habitat facilitation; herbivory; Kenyan Acacia savannas; keystone species; Loxodonta africana; Lygodactylus keniensis; positive interactions; quantile regression; trait-mediated indirect effects.

Males of a Croatian population of the lacertid lizard Podarcis melisellensis exhibit a striking polymorphism, with coloration of the throat and abdomen ranging from completely white, to yellow or orange. In a first attempt to explore the potential ecological and evolutionary significance of this polymorphism, we compared the three forms of males in aspects of their morphology, whole-animal performance, behavior, and ecology. Orange males are, on average, larger in snout-vent length and have disproportionately larger heads than either white or yellow males. This is reflected in orange males having higher bite force capacity and theoretically an increased access to harder prey. Residual limb length, maximal sprint speed and maximal exertion do not differ among color morphs. Body temperatures in the field are similar in the three morphs, but yellow males are caught at sites with slightly higher air temperatures than are orange and white males. Behavioral observations show no differences in time budgets or in the timing of activities among morphs. Microhabitat use is also similar in the three color morphs, but orange males were more often initially seen on rocky substrates. Our findings suggest that the observed polymorphism likely, does not originate from a divergence in niche or use of resources, but possibly reflects an underlying polymorphism in mating tactics.

Males and females are known to differ in a whole suite of characteristics, such as morphology, physiology, ecology, and behavior. Intersexual differences are generally believed to arise because of differences in selective pressures on either sex. In this study, we investigated whether intersexual differences in escape behavior exist in lizards of the genus Anolis, and whether these could be explained by intersexual differences in body size and/or microhabitat use. To do so, we compared the behavioral response to an approaching human predator in the field in males and females of 12 Anolis species. We found that ecomorphs and sexes differ greatly with respect to escape behavior. Twig anoles have the shortest approach distance (i.e., distance between the observer and the lizard when it starts fleeing) and final distance (i.e., distance between the observer and the lizard when it stops moving), compared with the other ecomorphs. The distance fled, on the contrary, is greatest in twig anoles. Also, females flee less soon and run over shorter distances than do males. Since twig anoles are considered the most cryptic anoles, and females may be less conspicuous than males, these results corroborate the idea that well camouflaged animals allow predators to come closer. The interspecific variation in sexual dimorphism in escape behavior, however, cannot be explained by the interspecific variation in sexual size dimorphism or sexual dimorphism in microhabitat use. Thus, escape behavior appears determined by different factors in males and females.

Abstract: Researches are keen to know astonishing and intricate details of the nature. Each creature has its own admiring abilities and performs their routine task in more efficient manner. The [...]

The ability to assess body size during territorial contests should be an adaptive attribute that influences the tactics of intermale aggression. The results indicate that if smaller males of Anolis carolinensis have breeding territories, then they will engage in costly contests, despite a low probability of defeating larger and equally motivated opponents.

It is relatively easy to document direct agonistic interactions among of within species that lead to exclusion of subordinate animals from preferred habitats. It is more difficult to measure the competitive effects of that exclusion on the 'loser.' Thus, much behavioral research assumes that the intensity of agonistic interactions is correlated with their cost to performance, but does not directly measure such a cost. We examined fitness-associated traits of pregnant viviparous scincid lizards (Eulamprus heatwolei) in outdoor enclosures under three conditions: alone, with a conspecific, or with a larger and more aggressive heterospecific (Egernia saxatilis, a sympatric scincid species). As in previous laboratory studies, Egernia saxatilis attacked Eulamprus heatwolei and excluded individuals of the smaller species from warmer shelter sites. However. Eulamprus heatwolei were able to maintain 'normal' schedules of body temperatures and food intake, apparently by modifying their behavior to minimize encounters with their aggressive cage mates. Accordingly, the subordinate animals showed no overt iii effects in spite of strong agonistic interactions: the body condition, locomotor performance, and corticosterone levels of subordinate Eulamprus housed with Egernia were indistinguishable from those of lizards kept in solitary cages or with conspecifics only. Similarly, the offspring of these pregnant females were born at the same time, and with similar phenotypic traits, as the offspring of control females. Thus, even in situations of intense interspecific aggression and consequent habitat exclusion, behavioral flexibility of the subordinate animals may decrease or eliminate the inferred ecological consequences of that interaction. Key words: aggression; agonistic behavior; behavioral flexibility; habitat exclusion; Egernia saxatilis; Eulamprus heatwolei; intraspecific; interspecific; scincid lizards; shelter; shelter sites; skink.

The parental care in black rock skinks, Egernia saxatilis, from southeastern Australia is investigated. The study indicates that some lizards display postpartum parental care, which in turn benefits their progeny via reduced risk of infanticide and better access to thermal and nutritional resources.

Prey might assess that risk level estimated in the first encounter with a predator was fixed in subsequent responses, whereas prey using flexible behavior would track short-term changes in risk. The authors examined, in the field, refuge use of Iberian rock lizards (Lacerta monticola) after simulated predator attacks and tested (a) how risk was assessed when multiple sources of risk were present simultaneously, (b) how short-term changes in risk level of successive attacks affected refuge use, and (c) whether the interval between attacks was important, insofar as attacks were considered to be coming from the same or different predators. Results suggest that lizards have a flexible estimate of risk that is based on multiple sources and flexibly dependent on previous estimates.

We performed a laboratory common-environment study to determine the genetic and environmental sources of variation in growth rates of the sagebrush lizard (Sceloporus graciosus). Hatchling lizards were reared from gravid females collected from three study populations along an elevational gradient in southern Utah, USA. Hatchlings were fed ad libidum and were maintained on a 14:10 light:dark cycle, with temperatures at 33[degrees]C and 21[degrees]C during photophase and scotophase, respectively. Each hatchling was randomly assigned to either a water-supplementation treatment or a control group receiving no supplemental water. Once every five days, the water-supplemented lizards were administered orally a quantity of water equal to 5% of their body mass. Growth was quantified as the total change in body size (length and mass) for 30 d after hatching. Resting metabolic rates of a subset of lizards were measured at hatching and at the end of the study. After adjusting growth for food intake, change in length did not differ between water-supplemented and control lizards, and did not differ among the three populations. Metabolic rates were similar across the study for all treatment groups. Water-supplemented lizards did gain wet mass more rapidly than control lizards; however, the difference in growth between groups was attributed to hydration state, because growth in dry mass did not differ between groups. The effects of water supplementation on growth that were observed by other investigators were likely manifested through changes in thermoregulatory behavior or increased activity. Key words: altitudinal effect on life history; common-environment study; countergradient variation; geographic variation; growth rates; intraspecific variation; life history; phenotypic plasticity; sagebrush lizard; Sceloporus graciosus; water availability.

Resource subsidies from external habitats can enhance the performance or population density of local consumers, altering their effects on in situ prey. Indirect effects of subsidies may be either positive or negative depending on the behavior of the shared consumer. Here we document strong links between riverine insects, riparian lizards (Sceloporus occidentalis), and terrestrial invertebrates. We hypothesized that aquatic insects subsidize riparian lizard populations leading to higher growth rates of these lizards in near-river habitats, and that subsidies exert short-term positive effects on terrestrial resources as a result of diet shifts by lizards to aquatic insects. To test these hypotheses, we used 2 in high fences, or 'subsidy shields,' to experimentally reduce aquatic insect flux to large (91 [m.sup.2]) enclosures of lizards. Subsidy shields reduced aquatic insect flux by 55-65%. Growth rates of lizards were 7x higher in subsidized (no-shield) enclosures during the early summer but were not significantly different later in the summer, when ambient fluxes of aquatic insects dropped to 20% of their early season levels. Within the watershed, lizard growth rates (in mass) were positively correlated with the numerical abundance of aquatic insects. Thus, lizard growth rates tracked both seasonal and spatial availability of riverine insect subsidies during our experiment. Subsidies also had indirect effects on the ground-dwelling, terrestrial prey of lizards. Declines of diurnal terrestrial invertebrates were significantly higher in shield than no-shield enclosures, and the most common ground spider (Arctosa sp. [Lycosidae])disappeared completely from shield enclosures by the end of the experiment. Declines in terrestrial invertebrate abundance did not differ between no-shield enclosures and lizard exclosures. These data suggest that riverine insects subsidize riparian Sceloporus and, in the short term, reduce their predation on terrestrial arthropods. Key words: Arctosa sp.; functional response; ground spider; lizard; predation; riparian; river; river-watershed exchange; Sceloporus occidentalis; subsidy; watershed.

The evolution of scent-mediated behavior has been studied in the rock-dwelling velvet gecko (Oedura lesueurii) using modern comparative methods and a snake species, Hodeplocephalus bungaroides, as the selective agent. The results give support for an often-suggested, nevertheless speculative, idea that prey can adapt to predation pressure on a small local scale.

The maximal running speeds of lizards have commonly been measured using level racetracks in a laboratory, but the normal speeds of locomotion of lizards and most animals in their natural habitats are not well documented. Thus we quantified the locomotor activity of the lizard Uma scoparia in its natural sand-dune habitat to determine how commonly animals run near their maximal speed and how inclines in the environment might affect habitat use and the speed of locomotion. We used leaf blowers to erase footprints in the sand in three 40 m x 100 m plots differing in surface topography and vegetation and then measured attributes of the paths and tracks left by U. scoparia that were not disturbed (by observers) during their period of peak activity. Laboratory observations allowed us to estimate speed for each field measurement of stride length (n = 5993). The frequency distribution of stride speed had two distinct modes (mean values 0.25 and 2.00 m/s), for which only the lower one is likely to be aerobically sustainable. Bipedal locomotion was extremely rare ( Keywords: desert; lizard; locomotion, preferred speed; Mojave Desert, USA; sand dune; slope; Uma scoparia.

The females of certain species are highly aggressive but little is known about the effects on such behaviour of steroid hormones. A new study of mountain spiny lizards examines seasonal patterns of territorial aggression and relates them to levels of the plasma steroid hormones testosterone, corticosterone, dihydrotestosterone and oestradiol. It is suggested that testosterone and oestradiol may promote female aggression while corticosterone suppresses it. However, no one-to-one association between steroid hormones and female aggression has been found, suggesting that other factors and interactions may be involved.

Push up displays in three populations of sagebrush lizards, Sceloropus graciosus, were monitored to determine variation in the display behavior in different populations. Differences in display body postures, the number of legs extended to display the up-and-down motion and the number of headbobs differ in the three populations under investigation. Further, each population has at least one unique behavior. The push-up display appears to be undergoing a rapid change in structure and function.

Yearling male collard lizards, Crotaphytus collaris, increased their patrol, display and intrasexual encounters in the absence of two-year and older males. The significant increase in intersexual encounters when there are no adult males around suggests that females become more receptive to yearling the longer adult males were absent. These findings indicate that social behavioral patterns of male collard lizards are based on social feedback.

The escape tracks of the Mojave fringe-toed lizard, Uma scoparia, were investigated to determine the use of inclined surfaces and measure the performance during escape in this dune-dwelling species. Results show that the direction of the initial 1-m segment of the escape trajectory is away from the perceived threat but does not necessarily follow the direction with the least incline or the closest cover. Speed was maximized on level surfaces and the laboratory performance of these lizards is only 75% of that measured in the field.

Steroid hormones are responsible for the hormonal responses to aggressive encounters in the two male morphs of tree lizards, Urosaurus ornatus. The two morphs are an aggressive, territorial morph and a less aggressive, non-territorial morph. The aggressive morphs have increased levels of corticosterone and decreased levels of testosterone when subjected to an encounter. The hormonal changes in the less aggressive morph influence the agonistic behavior in male-male interactions and the energy spent during these interactions.

The feeding behavior of the white-throated savannah monitor was analyzed to determine possible sensory cues that affect foraging decisions. Several lizards were subjected to different sensory cues relating to their choice prey, land snails. Results showed that the lizards differentiated between land snails using both visual and chemical cues. Moreover, they tended to select large land snails over smaller ones, suggesting a possible selectivity in obtaining a high caloric reward for minimal energy exertion.

Australian lizards of Tiliqua rugosa and Egernia stokesii species show kin recognition even when separated from mothers at birth and kept either in isolation or with a foster mother. Both mothers and offspring have the ability to discriminate between kin and non-kin. This is evident by more attention and tongue flicks directed toward related than non-related lizards. Foster mothers spend more time with their own non-familiar young compared to familiar foster young. This mother-offspring recognition may be possible due to olfactory cues, recognition alleys, or phenotype matching.

Decreasing the perch diameter in lab conditions leads to a decrease in sprint speed but has an insignificant effect on the jumping ability of Anolis lizards. The effect of perch diameter on the escape behavior of lizards can be predicted by diameter effect on locomotor capacities of lizards. The jumping ability of lizards depends upon the location, to maximize their locomotor abilities.

A study to explain the dorsal darkening behavior in male tree lizards, Urosaurus ornatus, helped reveal that males use this coloring trait to display their territorial status and dominant role as protectors of the females of the species. Males display this behavioral trait more in groups consisting of females and less in groups solely consisting of males.

Captive, subadult white-throated savanna monitor lizards (Varanus albigularis; n = 15) were tested in a prey density-dependent foraging experiment. Within a test arena individual lizards were offered 10 large and 10 small snails in both a large and small circular area. Results showed that at high prey density, these lizards selected large over small snails. At low prey densities, however, large and small snails were selected at an equal rate. Apparently, when prey densities are high, the lizards have the opportunity to select the larger prey items without incurring locomotor costs. These data support optimal foraging theory but are unique in that they are an example from a little-studied, widely foraging species of lizard.

Xia and Boonstra's criticism that researchers tend to underestimate temporal variability of territorial animals such as lizards may still be valid for the 1985 survey showing relatively constant lizard populations. The survey included sites with both high and low populations that did not differ much in variability. The variability of the Anolis species, which are more territorial than other lizards, was higher than that of other lizards.

The parthenogenetic whiptail lizard Cnemidophorus laredoensis is comprised of two genetically distinct clonal complexes (=lineages) that arose from separate hybridizations between sexual species. The hierarchical model of E. D. Parker, Jr., J. M. Walker and M. A. Paulissen predicts that parthenogens that originate from multiple hybridizations should differ in ecological and behavioral traits. I tested this prediction by analyzing the microhabitat use and antipredator escape behaviors of the two C. laredoensis clonal complexes in a relict subtropical forest/bunchgrass-weed-mesquite habitat in southern Texas. Both clonal complexes used microhabitats with loose sandy soil, dense grass and partly or completely open forest canopy more often than expected if lizards used microhabitats at random. Measurements of lizard movements in reaction to a human 'predator' showed that both clonal complexes permitted shorter initial and final approach distances, and had shorter flight distances than other Cnemidophorus that have been studied. There was no difference in the microhabitat use, escape distances or escape behaviors of the two clonal complexes. A previous study showed that the two clonal complexes did differ in diet and activity pattern; the overall conclusion is that the two clonal complexes show ecological differences in some parameters but not others. Since this is often the case among syntopic congeners, the general prediction of ecological difference between genetically distinct parthenogens is upheld.

Defined and unique male territorial headbob signal patterns, designated as types A, B and C, are evident for the lizard Anolis carolinensis. Isolation and pairing of males during territorial contests exhibited all of the headbob signalling in these categories. Functional classifications for display behaviors should be eliminated, regardless of the taxon analyzed.

Males in tree lizards, Urosaurus ornatus, with blue or green throat dominate in polymorphic populations more than those with less blue/green and more orange throats. Experiments in semi-natural outdoor conditions, however, show it is the dorsal darkening of the males that suggests the dominance status. Thus, the hypothesis that throat signal takes precedence over dorsal signal when throat coloration is different among males is wrong. In monomorphic species, too, a higher dominance is symbolized by dorsal-darkening.