Session 6: Herpetology Behavior IRoom: Room 206D2022-07-28 13:30 - 14:45 |
| Moderator: Daniel Warner |
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1. 13:30 Boldness and Behavioral Syndromes Across an Urban Gradient in the Brown Anole (Anolis sagrei). Robyn Screen*, University of Hawai?i at M?noa; Amber Wright, University of Hawai?i at M?noa rmscreen@hawaii.edu
Animals in urban environments tend to exhibit different behavioral traits than their conspecifics. Specifically, they tend to be bolder, displaying more risk-taking behaviors that aid in resource use in novel or changing environments. Anolis lizards provide an ideal study system for understanding traits driving success of invasive species in urban habitats. In this study we assess 1. Whether a boldness syndrome exists in brown anoles (Anolis sagrei) on the island of O?ahu and 2. Whether urban populations are, on average, bolder than rural populations. We performed behavioral assays on free-ranging animals in the field at eight sites throughout Honolulu, O?ahu. We measured structural habitat characteristics, human activity, bird abundance, prey abundance, and lizard density to quantitatively characterize an urban-rural gradient. Across the eight sites we caught and marked over 650 lizards, allowing us to resight and perform assays on 279 individuals. An intraclass correlation coefficient indicates that within-individual behavioral consistency exists but is weak (ICC = 0.14, 95%CI = (0.069, 0.22)), while a mixed model approach similarly found that lizard ID explained a modest 24% of the variance in behavior. While this study demonstrates that a boldness syndrome exists in A. sagrei on O?ahu, there does not appear to be a difference in behavioral responses in urban and rural populations. The introduction of A. sagrei to O?ahu is relatively recent. Lizards are still actively spreading into new habitats potentially favoring mixed populations rather than monocultures of only bold or shy lizards. |
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2. 13:45 Relative Body Size and Genetic Relatedness Affect Female Social Networks in Gopher Tortoises (Gopherus polyphemus). Betsie Rothermel*, Archbold Biological Station; Rebecca McKee, University of Florida; Tracey Tuberville, University of Georgia, Savannah River Ecology Laboratory; Amanda West, Archbold Biological Station; K. Nicole White, Archbold Biological Station; Michael Yuan, University of California; Kelly Zamudio, University of Texas brothermel@archbold-station.org
Knowledge of reptilian social behaviors is limited, even for otherwise well-studied species like the Gopher Tortoise (Gopherus polyphemus). Current conservation programs for this threatened, keystone species of upland ecosystems in the southeastern US operate with little understanding of how social behaviors may affect space use, dispersal, and individual fitness in either natural or translocated populations. Building on past research (Guyer et al.) that documented social structure (cliques) and breakdown of social networks at low population densities, we examined female social dynamics in a natural, high-density population of Gopher Tortoises at Archbold Biological Station, Florida. We continuously monitored 37 adult females with telemetry and motion-activated cameras from March-September 2015, resulting in a dataset of 349 interactions involving 67 unique female-female pairs. From videos, we classified interactions as burrow visits, non-aggressive interactions, and aggressive interactions. Despite overlapping space use by many individuals, the undirected network of all interactions was structured into 7 clusters of highly connected females. 78% of pairs had at least one aggressive encounter and 50% of all recorded interactions involved aggressive behaviors (e.g., chasing, ramming, flipping). We used exponential random graph modeling to examine effects of size and relatedness metrics on the directed network of aggressive interactions (n = 141). Probability of aggressive interaction increased as the size advantage of the visiting tortoise (relative to the resident) increased. In contrast, probability of aggression decreased as pairwise relatedness increased. Our preliminary results provide novel evidence of size-mediated social dynamics and kin-based sociality among female Gopherus. |
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3. 14:00 The role of headwater fish in limiting the downstream distributions of stream salamanders. Kristen Cecala*, University of the South; Eli Walker, University of the South; Belle Morris, University of the South; Elizabeth Culp, University of the South; Shawna Fix, Tennessee Aquarium Conservation Institute kkcecala@sewanee.edu
Stream salamanders dominate headwater stream communities as the primary top predators. Their distribution is restricted to ephemeral and perennial low-order streams. The mechanism maintaining this upstream distribution has been associated with upstream-biased movement, predator avoidance, susceptibility to high flow velocities, and even low detection in deeper water, but few studies have examined the strength of evidence for these hypotheses. We used ex-situ mesocosms to explore the performance and habitat selection responses of salamanders to headwater fish. Both larval and adult life stages perform poorly in the presence of fish despite fish being caged to prevent physical interactions. Furthermore, when provided with land to escape the presence of fish, adult salamanders select for terrestrial habitat more often, and poor performance in the presence of fish is maintained even when terrestrial prey is available. Avoidance of aquatic habitat in the presence of fish may reduce the resilience of downstream populations to additional stressors including forest conversion and climate change further isolating headwater salamander populations. |
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4. 14:15 Microhabitat partitioning by Side-blotched Lizards (Uta stansburiana) and Sagebrush Lizards (Sceloporus graciosus) minimizes competition. Pete Zani*, University of Wisconsin-Stevens Point petezani@gmail.com
The study of competition in natural settings can be difficult if species engage in macro- or micro-habitat partitioning, or otherwise structure their community. One result is that much of what we know about behavioral contextualization during intra- and inter-specific interactions comes from semi-natural arena or laboratory studies. I report on 300 hours of behavioral observation between three species of lizards (Side-blotched Lizards [Uta stansburiana], Western Fence Lizards [Sceloporus occidentalis], Sagebrush Lizards [S. graciosus]) that co-occur at relatively high abundances at a site in east-central Oregon. Observations resulted in over 1000 natural interactions, 400 of which were uncounfouded by other lizard-lizard interactions. Despite Uta and S. graciosus being supposed competitors, I found no evidence that Side-blotched Lizards contextualize their display or movement behavior, modify their perch characteristics, or engage in high intensity or aggressive interactions toward either heterospecific lizard. Rather, Side-blotched Lizards reserve behavioral modification for intersexual (male-female) Uta-Uta interactions, which indicates that lizard competition in Uta is nearly entirely intraspecific, even when these species co-occur at microgeographic scales. The unique habitat characteristics at this study site caused by recent nearby volcanic eruptions are the apparent cause of these lizards’ co-occurrence, but extreme micro-habitat preferences minimize most of these interactions in this lizard assemblage. |
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5. 14:30 Do female lizards choose nest sites based on the predictability of substrate moisture? Daniel Warner*, Auburn University; Jenna Pruett, University of Colorado; Amélie Fargevieille, University of Montpellier; Randy Klabacka, Auburn University daw0036@auburn.edu
Nesting behavior is an important part of reproduction that affects the fitness of mothers and their offspring. Females of most oviparous species choose microhabitats for nesting that have positive effects on embryo development. However, choosing suitable nest microhabitats could be challenging in environments that fluctuate unpredictably. In many reptiles, females avoid nesting in dry microhabitats because eggs will rapidly desiccate. In nature, however, microhabitats with suitable hydric conditions at the time of oviposition may eventually become lethally dry during incubation. We hypothesize that females avoid nesting in locations with unpredictable fluctuations in substrate moisture because of potential detrimental effects on their developing offspring. To test this, we provided captive brown anoles (Anolis sagrei) three nest conditions to choose among: 1) substrate that predictably alternated between suitable and lethal moisture conditions, 2) substrate that fluctuated unpredictably between suitable and lethal conditions, and 3) substrate with moisture levels that remained constant. For the constant choice, some females could choose moist substrate (a “safe” choice), and others could choose dry substrate (an “unsafe” choice). Females almost always nested in substrates that were moist at the time of oviposition, regardless of the level of predictability. Additionally, while constantly dry substrate was avoided, maternal choice of nest site was equally divided between the predictable and unpredictable conditions. These results suggest that nest site choice is based on immediate environmental cues, rather than the level of predictability of future conditions of nest sites, which could result in poor nesting decisions in fluctuating environments. |