Maria A. Eifler

Food availability can affect growth, space use, and behavior of individuals. We examined sex-based effects of experimentally provisioned prey on growth rates, home ranges, and behavior of Sceloporus woodi in southern Florida. We provided supplemental crickets, comparing home range and core area size, growth rates, and behavioral profiles of individuals on supplemented and control plots. Control males had larger home ranges than females, but the sexes did not differ on food-supplemented plots. Core area size did not differ with either sex or treatment. Males and females on control plots did not differ in growth rates, but on supplemented plots females grew several times faster than males (mass and SVL). Supplemental food also led to sex differences in movement rates and habitat use. On supplemented plots, males moved at a 4× higher rate than females, but habitat use did not differ by sex. By contrast, on control plots, movement rates did not differ, but habitat use did: females spent more time on the ground, and males spent more time off the ground. We did not detect any other behavioral differences. The relatively high growth and low movement rates of supplemented females underscore the importance of sex-based foraging and reproductive tradeoffs that affect the way in which individuals grow and arrange themselves spatially.

Landscape structure can affect movement, which is influenced by foraging, thermoregulation, and predation risk. We evaluated search paths relative to landscape cover for a unisexual lizard (Aspidoscelis uniparens) whose movement is primarily motivated by foraging. In outdoor enclosures, we arranged artificial plants in three distributions (uniform, mildly clumped, heavily clumped cover), testing the hypotheses that search effort and efficiency will vary with landscape configuration, and that movement patterns will reflect changes in foraging to accommodate thermoregulation and predation avoidance. We recorded movement parameters, assessing search paths relative to effort, efficiency, and space use. Effort did not vary with landscape configuration, but efficiency, movement patterns, and space use varied with plant distribution. With mildly clumped cover, lizards entered plants more frequently than in other cover configurations. Lizards in both clumped configurations preferentially used areas with more plants. Plant residence times also varied—short-duration visits occurred most often with mildly clumped cover, but with heavily clumped cover, long-duration visits were most common and median residence times were longest. The likelihood of moving to the nearest plant was highest with uniform cover, and that of revisiting plants was lowest with heavily clumped cover. The distribution of cover influenced movement patterns, space use, and search efficiency, likely arising from variation in predation risk.

Differences in body size and development can result in ecological variation with age, although juveniles often are understudied. Among bushveld lizards, juveniles are morphologically distinct from adults, with their movement and coloration mimicking beetles. We examined movement in a population of juvenile bushveld lizards in southwestern Botswana. In our study population, juveniles were active foragers, exhibiting both high moves per minute (MPM) and percent time moving (PTM) relative to other lizards. We also measured first passage time (FPT; radii = 1, 3, and 5 m), which revealed that foraging juveniles use area restricted searching. Across the limited range of scales we examined, FPT increased linearly, possibly indicating directional persistence. Further studies on the implications of our findings are merited.

Successful escapes depend on many factors, including predator type and habitat characteristics. Examining escape usually entails directly pursuing an individual and then measuring flight initiation distance (FID), but the effect of prolonged pursuit has not been well studied. We examined escape sequences by blanched adult lesser earless lizards (Holbrookia maculata) in the Salt Basin Dunes (SBDs), testing the hypothesis that escape success and sequences would vary with sex and vegetation use. Their coloration is an adaptation to their sparsely vegetated white sand habitat. To evaluate escape behavior, we followed an individual directly until it disappeared (=successful escape), stopped moving, or 2 min elapsed. We recorded trial habitat (at the start and throughout), time to trial end, FID, length of moves, and total distance moved. FID varied with starting habitat—lizards beginning trials on exposed wood had the longest FID. The sexes differed in their move lengths: females made more short moves, while males made more long moves. The most important plant was sage (Artemisia filifolia), which was occupied at the start of 39% of trials, while 71% of trials ended in sage, and larger sage bushes supported longer escape sequences. Our study highlights the importance of vegetation for refuge and emphasizes the crucial role of the dune-plant landscape to lesser earless lizards.

Within-species differences in morphology can influence many aspects of an organism’s ecology. Weinvestigated the morphology and habitat use of Bosc’s Fringe-Toed Lizard (Acanthodactylus boskianus) in sub-desertsteppe habitat in central Tunisia. Our main objective was to verify the presence of sexual size dimorphism in our studypopulation and assess whether morphological differences between males and females corresponded to differences invegetation use while being pursued. We captured, measured, and then released 60 adults after conducting habitat assessmenttrials, which consisted of pursuing an active lizard and recording the vegetation into which the lizardescaped. Concurrently, we conducted vegetation transects throughout the study site to assess vegetation availability. Werecorded values for ten morphometric measures, all of which were larger for males than for females. For most measures,males and females of the same SVL had comparable values. However, a positive interaction between SVL and sex wasevident, with males exhibiting increasingly larger hindlimbs and mass. Our investigation revealed selective habitat-usepatterns among A. boskianus that were independent of sex and body size. Lizards did not use plants based on theiravailability, entering Aristida pungens (Three-awn Grass) and Retama raetam (White Broom) more but Rhanteriumsuaveolens (Rhanterium) and Haloxylon schmittianum (Saxaul) less frequently than random expectations. For the threemost commonly used plants (Astragulus armatus (Milkvetch), Three-awn Grass, and White Broom), lizards chose toenter larger plants. This use of habitat could stem from antipredator defense or thermoregulatory concerns. Our findingsdiffer from previous reports on the nature of sexual size dimorphism in A. boskianus and contribute to our understandingof the complex interplay between morphology, behavior, and local environmental conditions in shaping theecology of A. boskianus.

The optimal search strategy for foraging animals can vary based on environmental parameters, which can include information about the spatial distribution of prey. We tested the hypothesis that natural populations of foraging desert grassland whiptails (Aspidoscelis uniparens) structure their search strategies according to resource distribution. We experimentally provisioned prey in uniform, aggregated, and random distributions to characterize search effort (moves per minute and percent time moving) and search path (turn angles, movement duration, path straightness, step length, and two-step sequences). The search effort did not vary with treatment but animals adjusted their search path based on the presence and distribution of supplemental prey. With uniformly distributed prey, foragers took longer step lengths and more frequently engaged in two-step sequences that included long step lengths. When prey were randomly distributed, foragers made more moves of long duration and fewer straight moves, often pairing short step lengths with large turns. With an aggregated prey distribution, foragers had more moves of very short duration. Examining detailed search path characteristics can identify responses to environmental changes. Under experimental conditions, the search strategies of A. uniparens indicated behavioral responses to food distribution that could improve search efficiency.

For small ectotherms, thermal conditions and habitat structure can drive local adaptations in behavior and habitat use. The water anole, Anolis aquaticus, is a semiaquatic lizard occurring along streams in lowland tropical sites, as well as at higher elevations with greater thermal variability. We studied their thermal ecology, habitat use, and behavior at a high- (~1100 m) and low-elevation (~sea level) site in Costa Rica to assess the relationship between thermal environment and behavioral ecology. We measured behavior through focal observations (rates of movement, head turns, and feeding) and recorded the range of environmental temperatures, body temperatures, air and substrate temperatures of perches, and habitat use (perch location relative to water’s edge and current, substrate, cover, and visibility). The low-elevation site had higher minimum temperatures and a smaller range of available temperatures. Body temperature and size varied with site and sex: low-elevation males had the highest body temperatures, and high-elevation males were largest. Individuals at the high-elevation site were less active, perched closer to the water’s edge (shorter horizontal perch distance), and more often used the ground or rocks near an eddy as a substrate than individuals at the low-elevation site. The temperature and habitat structure of water courses can manifest phenotypic differences in ecology and behavior.

Demographic constraints can have a profound effect on behavioral ecology. Yet examinations of intraspecific variation considering both sex and age are rare. We assess age and sex-specific habitat use, movement, and behavior in variegated toad-headed agamas (Phrynocephalus versicolor) in the Gobi Desert, Mongolia. We predicted that juveniles would move and forage more than either adult sex and would engage in more random movement paths (i.e., higher entropy) than adults. We conducted 15 min focal observations, marking locations every 30 s to delineate the movement path of individuals. We recorded foraging and tail displays throughout the observation and habitat data at each marker. We found no sex-specific variation in behavior, number of moves, or entropy, but did record sex-specific variation in habitat use and movement paths. Age-specific variation in behavior, movement, entropy, and habitat use was prevalent and nuanced. Juveniles ate, dug, moved, and tail displayed more than adults, and they had movement paths with higher entropy than either adult sex. Sex and age-based variation in behavior, movement, and habitat use could arise from differential body size, experience, or reproductive status. Future work is needed to understand the function of tail displays and the relationship of entropy in movement paths to behavioral ecology.

Through path analysis, most commonly applied to large animals moving long distances, we evaluated space use of Kalahari Desert lizards. We used sequences of locations to calculate step lengths and turn angles, revealing directed movement towards a central location. Consistent with homing, individuals moved < 30 m from their origin, progressing towards their start before venturing away. We illustrate that fine‐scale behavioural resolution can be obtained through movement paths, which can be invisible when applying common metrics focused on levels of movement (i.e., moves/min). Future research incorporating ecological data are needed to identify mechanisms underlying the movement patterns we document.

The great desert skink (Liopholis kintorei, locally known as tjakuṟa) occupies burrow systems in arid regions of central Australia. Most burrow systems remain occupied for an average of 4, and up to 10, years by the same related individuals. The circumstances associated with changes in occupancy are under active investigation. Factors linked to tjakuṟa abandoning burrow systems include intense fires and predation by feral cats (Felis catus). We examined ecological factors associated with whether burrow systems that were occupied in the previous year were currently occupied by tjakuṟa. We determined occupancy of previously occupied tjakuṟa burrow systems by the presence of fresh scats in their latrines. We also assessed the size, vegetation cover, and proximity of termite calics to burrow systems. Neither overall vegetation cover nor spinifex cover was related to burrow system occupancy, but larger burrow systems were more likely to remain occupied. Burrow systems within 10 m of termite structures were more—and those within 2.5 m of Grevillea were less—likely to remain occupied by tjakuṟa. The role of woody vegetation (Grevillea) and termite presence on risk of predation, the behavior of tjakuṟa, and burrow system occupancy merits further investigation on a longer timescale.