Erell Institute

Lawrence, KS, United States

Erell Institute

Lawrence, KS, United States
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Eifler M.A.,Erell Institute | Marchand R.,Salish Kootenai College | Eifler D.A.,Erell Institute | Malela K.,University of Botswana
Herpetologica | Year: 2017

Intraspecific variation in behavior is often associated with age or size class, with many animals experiencing ontogenetic differences in diet, predation risk, physiological function, and competition. The nature of intraspecific behavioral variation will depend on the environmental context and has been more thoroughly examined for diurnal species. We studied microhabitat use and activity relative to time of night and the lunar cycle for the nocturnal gecko Chondrodactylus turneri, in the Namib Desert. Geckos preferred larger rocks with more crevices and were clumped in their occupancy of rocks, with some rocks being occupied by as many as eight individuals. Age classes differed in their use of open areas, with juveniles being encountered more often in the open. Activity levels varied with moon phase and time, with adults and juveniles exhibiting different relationships. Our results indicate that multiple factors might be influencing intraspecific behavioral variation. © 2017 by The Herpetologists' League, Inc.

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

Eifler D.A.,University of Botswana | Eifler D.A.,Erell Institute | Baipidi K.,University of Botswana | Eifler M.A.,Erell Institute | And 2 more authors.
Journal of Ethology | Year: 2012

We experimentally determined that the lizard Pedioplanis namaquensis engages in area-restricted searching (=ARS, localized searching after encounters with food) while foraging and that prey characteristics influence ARS. Single prey items were introduced to free-ranging lizards, and their subsequent search effort was characterized using first passage times (=FPT, time required for an animal to cross a circle of a given radius). Three prey types were used: termites, flies, and rice (control). FPTs were longer following termite encounters than following fly or control encounters. Control treatments produced no change in FPT, while lizards searching for termites showed the greatest change. The use by Pedioplanis namaquensis of ARS was most pronounced for the typically aggregated prey type. © 2011 Japan Ethological Society and Springer.

Jacobson F.,University of Kansas | Garrison G.,Erell Institute | Penner J.,Goshen College | Gebin J.Z.,University of Sao Paulo | And 2 more authors.
Amphibia Reptilia | Year: 2016

Predation risk influences decision making, escape behaviour, and resource use. Risk assessment and behavioural responses to predation can depend on demographic and environmental factors. We studied the escape behaviour of the longnosed leopard lizard (Gambelia wislizenii) when approached by a human predator (= "simulated predator"), analysing flight initiation distance (FID) and flight distance (FD) relative to demographic and environmental variables. Starting distance (SD) of the simulated predator and orientation of prey lizards relative to the simulated predator influenced FID, but body size of the prey lizard did not. Sex interacted with SD to affect FID. Females lengthened their FIDs as SD increased, while male FID was unrelated to SD. Flight distance increased with increasing SD. Gambelia wislizenii's ecological role as an ambush predator may explain their escape behaviour; reproductive status potentially affected the interaction between sex and SD. © Koninklijke Brill NV, Leiden, 2016.

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
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.

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.

Garrison G.,University of Kansas | Phillips M.,University of Kansas | Eifler M.,Erell Institute | Eifler D.,Erell Institute
Amphibia Reptilia | Year: 2016

Ameiva corax is restricted to a small island (<2 ha), off the coast Anguilla.We present information on intraspecific variation in its diet, based on observations of 190 marked individuals. Larger individual were more likely to attempt to enter active seabird nests and only large males were observed to successfully enter a nest and break open an egg. Flower eating was commonly observed and its occurrence was not related to lizard size or sex. More than half the population was observed visiting areas where fisherman mixed their bait, a foraging strategy also unrelated to lizard size or sex. Ameiva corax is known to socially feed at large food items such as seabird eggs. The individuals that can initially access these food items may occupy key roles in the social network. © Koninklijke Brill NV, Leiden, 2016.

Eifler D.A.,Erell Institute | Eifler M.A.,Erell Institute
Behavioral Ecology | Year: 2014

The diet of the lizard Ameiva corax includes bird eggs and fruit, which are items that represent more food than a single individual typically consumes; lizards often congregate at these large food items. We examined the extent to which lizards aggregate and to which locating food might be facilitated by social factors. During surveys, individual A. corax were most commonly seen in association with other conspecifics, sometimes as many as seven. Experiments indicated that lizards were recruited to noteworthy items in the environment (fruit or a novel nonfood object) and that recruitment to food was greater than to a novel, nonedible object. Use of visual displays varied with experimental conditions; aggressive displays were not used by animals visiting nonfood objects or abundant food but were observed when food was moderately limited. A nonaggressive display, which may signal the presence of food and invite others to join, was most commonly used by lizards at food and decreased in frequency as the number of lizards present increased. Their pattern of aggregation and use of behavioral displays demonstrate social foraging in A. corax; the potential role of social networks merits further investigation. © 2014 International Society for Behavioral Ecology. All rights reserved.

Eifler D.A.,Erell Institute | Eifler M.A.,Erell Institute
Southwestern Naturalist | Year: 2010

The zebra-tailed lizard (Callisaurus draconoides) is a diurnal territorial insectivore from arid areas of North America. The underside of its tail has a series of black bands on a white background; individuals raise the tail to expose the underside as a social signal and to deter pursuit by predators. We characterized variation in banding of the tail within a population of C. draconoides from Sonora, Mexico, and examined the relationship between characteristics and use of the tail. Number of bands on intact tails was 410; individuals who have experienced some natural reduction in their tail can lack bands all together. The proportion of the underside of the tail that was black was 00.46. For males, snoutvent length and mass were positively correlated with number of bands and mean length of bars on the tail; snoutvent length, mass, and width of head were positively correlated with the proportion of black on tails. Females in better condition (based on residuals from regression of snoutvent length to mass) tended to have more bars on the tail and a wider head; snoutvent length, mass, and width of head were positively correlated with mean length of band. We simulated predator-prey interactions using humans as predators. Males used tail displays more than females. Individuals encountered in the open were more likely to use tail displays. Neither size of body nor natural reduction in tail was related to use of tail displays. During focal observations for females with reduced tails, rates of tail displays were positively correlated with length of tail. Males with intact tails moved more frequently and fed more often than males with reduced tails.

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