Joyce T.,University of Alaska Southeast |
Eifler D.A.,Erell Institute |
Powell R.,Avila University
Amphibia Reptilia | Year: 2010
Ecologically versatile Anolis schwartzi from St. Eustatius (Lesser Antilles) occurs in various habitats, usually in shaded situations and often in higher densities when associated with rock piles, rock slides, and stone walls. In order to evaluate the mating systems of A. schwartzi in different habitats, we examined populations in rocky and adjacent forested plots in Boven National Park to test the following predictions: (1) Population densities would be higher in habitats with rocks or rock slides than in nearby areas of forest without rocks. (2) Males would be larger in favoured habitats with higher population densities. (3) Behaviours related to territoriality and aggression would be more prevalent in habitats with higher population densities. In fact, population densities were higher in rock plots, males and females were larger in rock plots, and males engaged in territorial/aggressive behaviours (push-ups, movements, presumably necessary for surveying territories, and chases) more frequently in rock plots. Large male A. schwartzi in rock plots with high population densities apparently exclude small males (social exclusion hypothesis). Average female:male densities in forest plots approached 1:1, which is suggestive of monogamy, whereas that in rock plots was 0.72. Consequently, the mating systems of A. schwartzi appear to vary in a predictable manner along the spectrum of monogamy to polygyny between proximate habitats between which no genetic isolation is possible. © 2010 Koninklijke Brill NV, Leiden.
Eifler D.,Erell Institute |
Eifler M.,Erell Institute |
Malela K.,University of Botswana |
Childers J.,University of California at Berkeley
Journal of Ethology | Year: 2016
Ameiva corax is a diurnal, widely foraging lizard endemic to a small (<2 ha) Caribbean island and is known for social foraging, whereby individuals aggregate at large food items (e.g., bird eggs and cactus fruits). We characterized the social network for A. corax through focal observations and surveys, which delineated associations for 82 known individuals. Lizards varied greatly in the extent to which they were linked to the social network. Approximately 31 % of individuals were not observed in any associations while one individual associated with 22 % (n = 18) of the animals in the study area. Larger lizards tended to be more central to the social network; body size was positively correlated with number of associations (degree) and centrality (betweenness), but negatively correlated with average distance between an individual and its associates (mean path length). Larger individuals were also associated with lower clustering coefficients, indicating that their associates were less closely interconnected. Sex was not related to number of associations (degree), but did help explain some patterns. The extent to which a lizard’s associates were of the same sex (homophily) was related to both sex and body size. Females had lower homophily scores than males; within each sex larger lizards tended to have lower homophily. © 2016 Japan Ethological Society and Springer Japan
Allen K.E.,Truman State University |
Allen K.E.,Villanova University |
Aviles Rodriguez K.J.,University of Puerto Rico at San Juan |
Aviles Rodriguez K.J.,University of Rhode Island |
And 2 more authors.
Journal of Herpetology | Year: 2015
Both environmental factors and social factors affect an animal's choice of microhabitat. We explored the effects of humidity and the presence of conspecifics and predators on microhabitat selection by Brown-Speckled Sphaeros (Sphaerodactylus notatus; Squamata: Sphaerodactylidae). To test the effect of environmental moisture, we provided geckos a choice between shelters of varying humidity and determined that individuals were significantly more likely to choose more humid shelters. In interaction trials between conspecifics of different sizes and sexes and between geckos and predators, we found that lizards were unwilling to share shelters with conspecifics in all situations. We observed aggressive behaviors such as chasing, biting, and head bobbing and noted that subordinate geckos were unwilling to enter a shelter occupied by a dominant individual even in the presence of a predator. Copyright 2015 Society for the Study of Amphibians and Reptiles.
Eifler D.A.,Lawrence University |
Eifler M.A.,Erell Institute |
Brown T.K.,California State University, San Marcos
Southwestern Naturalist | Year: 2012
The Texas horned lizard, Phrynosoma cornutum, feeds primarily on harvester ants (Pogonomyrmex) across much of its range. We quantified behavior of P. cornutum foraging on Pogonomyrmex relative to habitat and time. For the duration of their morning activity, 14 lizards were observed; we determined their use of habitat and location of ants that were captured. Lizards spent most of their time under vegetation; the type of vegetation used varied throughout the morning. Most feeding took place in the open and involved ants dispersed away from colonies. When feeding under vegetation, most feeding took place under mesquites (Prosopis), and location of mesquites under which lizards fed was nonrandom with respect to distance from entrances to colonies of ants. Feeding at entrances to colonies was restricted to a shorter period of the morning than feeding on dispersed ants. Males and females differed in use of habitat and in foraging behavior, with males more likely to feed in the open and to feed at entrances of colonies than females.
Eifler D.,Erell Institute |
Eifler M.,Erell Institute
Amphibia Reptilia | Year: 2014
Successful escape from predators may involve the use of multiple tactics. The wedge-snouted desert lizard (Meroles cuneirostris) flees from predators through a series of discrete moves with each move representing a specific manoeuvre type. By simulating the approach of a predator, we examined the role of sex and age (adult vs. juvenile) on the manoeuvre types used during escape, as well as the relationship between the number of moves needed to escape and the number of manoeuvre types employed. The eight defined manoeuvre types were used by all demographic groups, though there were differences among groups in the tendency to use certain manoeuvre types. In general, there was a strong difference in how adults and juveniles fled from predators. The number of manoeuvre types used by a lizard tended to increase with the number of moves required to escape and adults more readily added new manoeuvre types to an escape sequence. Demographic differences in escape behaviour might result from differing predation pressures incurred by juveniles and adults, and might also be related to the ontogeny of escape behaviour. © 2014 Koninklijke Brill NV, Leiden.