Eumeces Laticeps Research Articles

Meristic Variation in Kansas Broad-Headed Skinks (Plestiodon laticeps) and Common Five-Lined Skinks (P. fasciatus)

The Broad-headed Skink is listed as Threatened in the state of Kansas under the Nongame and Endangered Species Conservation Act of 1975 and recent surveys have focused on this species. In Kansas, a similar species, the Common Five-lined Skink, occurs in the same range and habitats as the Broad-headed Skink. Visual characteristics of the two species overlap in hatchlings and sub-adults, where their bodies are black with five olive-colored lines that extend the length of their backs. Both species have bright blue tails until they reach maturity. The use of supralabial scale and postlabial scale counts is the most reliable way to distinguish between the two species; however, an individual may not represent the species exactly as stated in keys found within field guides. In the summers of 2016 and 2017, we collected genetic samples from Broad-headed Skinks and Common Five-lined Skinks and compared the genetic identification to meristic data collected in the field. We found Broad-headed Skinks express more variation in scale counts than Five-lined Skinks and the keys we used account for this variation.

Selective Host Attachment by Ixodes scapularis (Acari: Ixodidae): Tick-Lizard Associations in the Southeastern United States.

Questing behavior and host associations of immature blacklegged ticks, Ixodes scapularis Say, from the southeastern United States are known to differ from those in the north. To elucidate these relationships we describe host associations of larval and nymphal I. scapularis from 8 lizard species sampled from 5 sites in the southeastern U.S. Larvae and nymphs attached in greater numbers to larger lizards than to smaller lizards, with differential levels of attachment to different lizard species. Blacklegged ticks are generally attached to skinks of the genus Plestiodon in greater numbers per unit lizard weight than to anoles (Anolis) or fence lizards (Sceloporus). The broad-headed skink, Plestiodon laticeps (Schneider), was a particularly important host for immature I. scapularis in our study and in several previous studies of tick-host associations in the southeast. Blacklegged ticks show selective attachment to Plestiodon lizard hosts in the southeast, but whether this results from behavioral host preferences or from ecological factors such as timing or microhabitat distributions of tick questing and host activity remains to be determined.

Habitat Assessment of the Broad-Headed Skink (Plestiodon laticeps) and the Associated Squamate Community in Eastern Kansas

During the summers of 2015-2017, we performed standardized surveys across the known range of the Broad-headed Skink in eastern Kansas. We used a combination of drift fence arrays with funnel traps and visual encounter surveys (VES) to collect occurrence data on the Broad-headed Skink. A Canonical Correspondence Analysis (CCA) was used to determine which habitat variables explained the variation observed in the squamate assemblage. The position of the Broad-headed Skink was explained by average log length and overstory tree size. A secondary analysis implies the Broad-headed Skink is also associated with presence of Black Walnut (Juglans nigra). A logistic regression was used to determine which habitat variables were significant in predicting presence of the Broad-headed Skink. The variables from the most successful model included average log length, overstory tree size, understory tree dispersion, and overstory tree dispersion. These habitat attributes suggest the Broad-headed Skink prefers mature patches of forest, and habitat structure rather than tree species composition is more useful in predicting Broad-headed Skink presence.

Critical Habitat Assessment of the State Threatened Broad-Headed Skink

The Broad-Headed Skink is a semi-arboreal species that inhabits deciduous forests of the southeastern United States. Eastern Kansas makes up the northwestern periphery of their range and thus serves as an important area for studying the conservation of the species. In order to better evaluate the conservation status of the Broad-Headed Skink and develop a Recovery Plan, critical habitat needs to be better defined. In 2016, we surveyed 117 sites at Marais des Cygnes Wildlife Area, Marais des Cygnes National Wildlife Refuge, and La Cygne Wildlife Area. We installed drift fences, performed visual encounter surveys, and conducted a habitat evaluation at each site. A total of 560 individuals were collected that represented 32 species and 39 Broad-Headed Skinks were observed. Critical habitat variables were assessed using a logistic regression where we found insignificant results. However, these results will help guide us into the final field season of this project where we hope to increase our sample size.

Lizard Microhabitat and Microclimate Relationships in Southeastern Pine-Hardwood Forests Managed With Prescribed Burning and Thinning

Understanding the impacts of disturbances in forest ecosystems is essential for long-term biodiversity conservation. Many studies have evaluated wildlife responses to various disturbances but most generally do not use changes in microclimate features or microhabitat structure to explain these responses. We examined lizard responses to two common forest management practices (prescribed burning and thinning) in pine-hardwood forests of the Bankhead National Forest, Alabama, USA. Over 4 years, we captured 719 individual lizards representing seven species. Lizards exhibited species-specific responses to forest management: eastern fence lizard (Sceloporus undulatus) captures were positively associated with an increasing forest disturbance gradient and were greatest in thin with burn treatments, whereas little brown skink (Scincella lateralis) captures were positively associated with increasing litter depth and were greatest in control sites during the first year posttreatment. Green anole (Anolis carolinensis) captures increased in forest stands with concomitant increases in air temperature, whereas common five-lined skink (Plestiodon fasciatus) captures were related to coarse woody debris cover during posttreatment sampling. We were unable to detect a treatment response or microhabitat/microclimate associations for broad-headed skinks (Plestiodon laticeps). Through an information-theoretic approach, we were able to identify treatment effects along with changes in microclimate and microhabitat features potentially responsible for driving responses of southeastern lizard species to forest management.

Short term response of herpetofauna to oak regeneration treatments on the mid-Cumberland Plateau of southern Tennessee

We examined the short term response of herpetofauna to two treatments designed to regenerate oak in upland hardwood forest: (1) shelterwood (30–40% BA retention), and (2) oak-shelterwood (midstory removal by use of herbicide), along with controls. Research was conducted 1 and 2years post treatment within an oak-hickory forest within the mid-Cumberland Plateau of southern Tennessee. Reptiles and amphibians were captured using drift fences equipped with double-ended funnel traps and pitfall traps. The shelterwood treatment had the least canopy cover and greatest amount of light at the forest floor relative to oak shelterwood or control. These changes were the main drivers for increasing the complexity of forest vegetation within the stands. Fowler’s toads, eastern-narrow mouthed toads, northern slimy salamanders, eastern five-lined skinks, eastern fence lizards, northern black racers and smooth earth snakes were most abundant in the shelterwood treatment. Broad-headed skinks were most abundant in oak-shelterwood stands. Amphibian and reptile species richness was higher in the shelterwood stands than in oak-shelterwood or control. Reptile diversity was higher in the shelterwood treatment than controls. No negative responses for herpetofaunal abundance, richness, or diversity were detected in either treatment. These findings will provide forest resource managers and private forest land owners with better knowledge for conserving herpetofaunal species when implementing these oak regeneration methods in upland hardwood forests of the Cumberland Plateau.

Prey Size Selection under Simultaneous Choice by the Broad‐Headed Skink (Eumeces laticeps)

AbstractDiet selection among several prey types present in a dense aggregation, permitting a predator to become satiated without changing patches, may be important for predators that can eat many small prey items in a single bout. Choice in this scenario differs from that in optimal foraging models for sequential diet choice model and simultaneous choice models when travel time between patches is needed. Furthermore, satiation and depletion effects may be important in dense prey aggregations. We predicted that in dense prey aggregations, predators should eat the most profitable prey first, switching to smaller prey as larger ones become depleted and predators become satiated, and that prey below some minimum profitability should be rejected. When large numbers of prey of varying sizes were presented simultaneously, broad‐headed skinks (Eumeces laticeps) preferentially consumed large crickets, ate some medium‐sized crickets late in ingestion sequences, but ate no small crickets. Prey depletion, with selection of the currently most profitable prey type, appears to account for much of observed prey switching, and satiation may contribute. When four crickets of each of four sizes were presented, lizards ate largest first, then medium‐sized. Some then ate small crickets, but none ate very small crickets. These observations and exclusion of small crickets from the diet by many lizards when larger ones were unavailable support the predictions. In tests with three sizes of juvenile mice presented singly, the smallest were attacked at shortest latency and eaten, medium‐sized mice were attacked at greater latency but could not be subdued, and large mice were not attacked. These data suggest that as prey become too large to subdue and eat readily, profitability declines until they are excluded from the diet. Unsuccessful attacks on medium‐sized mice suggest that lizards had to learn their own capabilities with respect to a novel prey type.

ADJUSTING PREY HANDLING TIMES AND METHODS AFFECTS PROFITABILITY IN THE BROAD-HEADED SKINK (EUMECES LATICEPS)

Time spent pursuing, capturing, and subduing prey, and time spent preparing and swallowing it all affect profitability of a prey item (net energy gain/handling time). In the diet selection model of classical optimal foraging theory, handling time is constant for each prey type, but several factors affect it in some predators. We studied factors that might cause time spent to capture and handle prey by broad-headed skinks (Eumeces laticeps) to vary between and within prey types. Pursuit time did not vary with prey (cricket) size in experimental conditions. In three experiments using crickets of the same size, handling times for the first prey eaten were shorter when more prey were simultaneously present. Reduced handling time likely maximizes number of prey captured before the remaining prey escape. Preparation time (capture to initiation of swallowing) did not vary with prey number, but swallowing time decreased with number of prey present. This result suggests that lizards must prepare crickets thoroughly for digestion by bites puncturing the exoskeleton, which constrains them from decreasing preparation time. However, lizards can reduce handling time by swallowing more quickly, increasing the likelihood of capturing additional prey. Handling times were shortest for hungry skinks and longest just before satiation. Two factors may contribute to the increase in handling time with degree of satiation: (1) Motivation to capture prey declines as a predator becomes satiated, removing the reason for shortening handling times when groups of prey are present; (2) as the stomach and the esophagus are filled, mechanical constraints may slow swallowing. Preparation time, number of bites, swallowing time, and handling time increased with cricket size. Consequently, although it appears that the largest prey were the most profitable for sizes of crickets studied, this may not be true for other ranges of prey size. Preparation time was shorter for prey bitten on the head than on the side or back, but prey orientation during swallowing did not affect swallowing time. In summary, (1) when prey are present simultaneously, total energetic profit may be increased by reducing handling time, and (2) handling for specific prey types vary with satiation and handling method.

Increased predation risk while mate guarding as a cost of reproduction for male broad-headed skinks ( Eumeces laticeps )

We investigated antipredatory costs associated with mate guarding as potential costs of reproduction for male broad-headed skinks. Mate guarding by male lizards may increase fitness by preventing loss of fertilizations of the guarded female's eggs to other males, but it may have several costs. In addition to lost opportunities to search for additional females, risk of injury while fighting other males, and energetic expenditures while following females and fighting, guarding males might suffer increased risk of predation and reduction of opportunities to forage. We studied potential antipredatory costs of mate guarding by simulating predators searching for and approaching pairs of lizards in the field. Among pairs of lizards in close proximity to each other, males were detected before females 10 times more frequently than females were detected before males, and females fled before males much more frequently than males fled before females when pairs were approached, leaving the males exposed to the predator. After one or both lizards fled, males frequently followed females by scanning visually and scent trailing, exposing themselves to the predator while the female hid. Females never followed males. The implications of these findings for antipredatory costs of mate guarding are discussed.

Parasitism of lizards by immature stages of the blacklegged tick, Ixodes scapularis (Acari, Ixodidae).

From 1982-1985 and 1993-1999, a total of 309 individual reptiles, mostly lizards and snakes, belonging to 12 species (American alligator, six lizard species, five snake species) was captured on St. Catherine's Island, Liberty County, Georgia, USA, and examined for ticks. Three lizard species, the broad-headed skink Eumeces laticeps, southeastern 5-lined skink Eumeces inexpectatus, and eastern glass lizard Ophisaurus ventralis, were severely infested with larvae and nymphs of the blacklegged tick, Ixodes scapularis. Ticks were not found on any of the other reptile species. Overall, 80% of 65 E. inexpectatus examined were parasitized by a mean intensity of 21.5 larvae and 88% were parasitized by a mean intensity of 4.8 nymphs. Corresponding figures for E. laticeps (n=56) were 93% and 51.3 for larvae and 89% and 7.4 for nymphs, and for O. ventralis (n=3) were 67% and 22.5 for larvae and 100% and 21.3 for nymphs. Larvae and nymphs attached along the lateral grooves of O. ventralis. Nymphs attached mainly behind the ears and in the foreleg axillae whereas larvae mainly attached to these sites and on the hindlegs in Eumeces spp. Seasonally, both larvae and nymphs were recorded on lizards from April through October. A unimodal larval peak was recorded in May or June. Seasonal data for nymphs did not reveal any distinct peaks but small bimodal peaks in mean intensities may have occurred (one in early summer, the other in late summer) suggesting that some ticks complete their life cycle in one year, and others in two years, on St. Catherine's Island. Potential epidemiological consequences of these findings with respect to Lyme disease in the southeastern United States are briefly addressed.

TRADEOFFS BETWEEN PREDATION RISK AND FEEDING IN A LIZARD, THE BROAD-HEADED SKINK (EUMECES LATICEPS)

AbstractForaging, feeding, and escape decisions may all be modified by threat of predation. Field experiments using a human simulated predator show that a lizard, the broad - headed skink, Eumeces laticeps, alters several aspects of feeding behavior in ways suggesting tradeoffs between predation risk and feeding. When food (cricket) was closer to the predator, the lizards more frequently did not attack it, and often retreated to safety before consuming it, reducing the duration of exposure to predation. The probability of attacking a cricket decreased with distance of the lizard from refuge, reflecting greater risk due to increased time required to reach refuge. Latency to attack increased with distance of the lizard from refuge, suggesting that lizards assessed the risk as acceptable after observing the predator's continued immobility. Large crickets were attacked with higher probability and shorter latency than small crickets, indicating that greater risk was acceptable for greater energetic benefit. The lizards more frequently carried large than small crickets to refuges before eating them, reducing duration of exposure because handling time was greater for larger crickets. Smaller crickets were consumed where captured, again indicating modification of feeding behavior in response to predation risk. The skinks also reduced risk by reducing handling time when closer to the predator. Escape was delayed until a predator approached closer when lizards were eating than when not eating. This delay may reflect a tradeoff between predation risk and acquisition of food.

Tradeoffs between courtship, fighting, and antipredatory behavior by a lizard, Eumeces laticeps

Male fitness in many species depends strongly on social behaviors needed to obtain fertilizations and prevent loss of fertilizations to other males, but courtship, copulation, and fighting may incur increased risk of predation. When demands for reproductive and antipredatory behaviors conflict, fitness may be maximized by accepting some degree of risk to enhance reproductive success. To examine such tradeoffs, I introduced tethered conspecific males or females to adult male broad-headed skinks, Eumeces laticeps, in the field and observed how close they allowed a simulated predator (me) to approach before fleeing, or their latency to approach an introduced female located at different distances from the predator. When conspecific males were introduced, isolated and mate-guarding males initiated agonistic behaviors and permitted closer approach than control males, and mate-guarding males permitted closer approach than isolated males. When females were introduced, both isolated and mate-guarding males courted the introduced females and isolated males permitted closer approach than did mate-guarding males. These results for introduced males and females suggest that increasing risk was accepted when reproductive benefits were greater. Latency for isolated males to approach a conspecific female was greater when the predator was closer to the female, further suggesting sensitivity to predation risk during a reproductive opportunity. Relationships between reproductive and antipredatory behaviors have been studied much less than those between feeding and antipredatory behaviors, but this study indicates that animals balance increased risk of predation with the opportunity to perform several reproductively important behaviors.

Seasonal activity and host associations of Ixodes scapularis (Acari: Ixodidae) in southeastern Missouri.

Based on tick collections recovered from wild vertebrates and by dragging, the seasonal occurrence of adult blacklegged ticks, Ixodes scapularis Say, extended from October through May in southeastern Missouri. Adult activity was bimodal with the higher peak occurring in November followed by a lower peak in February. The activity of immature I. scapularis had the general pattern of that found in the Northeast where Lyme disease is hyperendemic, with larval activity (July) peaking after that of nymphs (May and June). Vertebrates varied in their importance as hosts of I. scapularis. White-tailed deer, Odocoileus virginanus (Zimmerman), and coyotes, Canis latrans Say, were the primary hosts of adult I. scapularis. Broad-headed skinks, Eumeces laticeps (Schneider), and eastern fence lizards, Sceloporus undulatus (Latreille), were the primary hosts of nymphal I. scapularis. The broad-headed skink, 5-lined skink, Eumeces fasciatus (L.), and Carolina wren, Thryothorus ludovicianus (Latham), were the primary hosts of larval I. scapularis. Homeotherms were important hosts of immature I. scapularis, accounting for 30% of nymphs and 39% of larvae collected. The eastern cottontail rabbit, Sylvilagus floridanus (Allen), may play an important role in the epidemiology of Lyme disease in Missouri. Isolates of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner were made from ticks recovered from rabbits, making the cottontail rabbit a key species for further study of the epidemiology of Lyme borreliosis in Missouri.

Reactive and anticipatory display to deflect predatory attack to an autotomous lizard tail

Antipredation display is usually directed to predators that have been detected, but might be beneficial when predators are likely to be dangerously close, but undetected. Anticipatory display could be selectively favored if it increased the probability of escape sufficiently to outweigh the increased probability of being detected and captured by a previously unaware predator. This is especially likely if prey have adaptations permitting a high probability of escape when attacked, such as deflection of attack to dispensible parts. Deflective displays typically occur under threat of imminent attack by a predator detected within striking distance, but might also occur in circumstances reliably entailing a high risk of ambush by undetected predators, especially immediately after an animal stops following a bout of locomotion. Tail undulation was observed in the broad-headed skink (Eumeces laticeps), a lizard with a conspicuous, autotomous tail that enhances escape ability. Eumeces laticeps undulated its tail before fleeing from a looming predator and immediately after stopping in the absence of a detected predator. Undulation after stopping confirms predictions of anticipatory deflective display and contradicts alternative hypotheses. Undulation just before flight from a predator very close at hand is a form of reactive deflection.

Effects of refuge and conspicuousness on escape behavior by the broad-headed skink (Eumeces laticeps)

Effects of refuge and conspicuousness on escape behavior by the broad-headed skink (Eumeces laticeps)

Risk Factors and Emergence from Refuge in the Lizard Eumeces Laticeps

AbstractI studied effects of three risk factors, predator proximity, persistence in attacking, and speed, on latency to emerge after entering a refuge in the scincid lizard Eumeces laticeps. I simulated a predator by directly approaching a lizard until it took refuge, usually a tree hole. Costs per unit time of lost opportunities to forage or engage in other activities enhancing fitness did not vary with risk factors. Skinks remained in refuges longer when I stayed near the refuges than when I withdrew to a greater distance. At both distances, skinks monitored my presence visually from positions at or near refuge entrances. Skinks remained in refuges longer after the second of two successive similar approaches at the same speed than after the first, suggesting that they perceived increased risk due to persistence by an individual predator, but the assessment might have been based on attack rate without individual recognition. Latency to emergence increased with predator approach speed, giving another indication of response to higher risk. If lizards were approached twice in succession, latency to emergence was much greater when predator speed was faster during the second approach. When the second approach was slower, there was no significant difference in latency between trials. Risks associated with speed and persistence thus simultaneously affect risk assessment. A recent model (Sih, 1992) of emergence from refuge supposes that decisions affecting latency to emerge are based on a balance of costs of remaining in refuge (often predominantly costs of lost opportunities for feeding or mating) against risk of predation. All data are consistent with a generalized view of Sih's (1992) model, but studies are needed to assess effects of cost and limited information about predator presence.

Threat Factors Affecting Antipredatory Behavior in the Broad-Headed Skink (Eumeces laticeps): Repeated Approach, Change in Predator Path, and Predator's Field of View

Antipredatory behavior can be studied from many perspectives, resulting in several distinct traditional foci in the saurological literature. Ethogrammatic efforts have produced extensive catalogs of defensive movement patterns (reviewed by Carpenter and Ferguson, 1977; Greene, 1988). A second very productive avenue has been experimental and observational study of costs, benefits, and correlates of defenses such as caudal autotomy and escape and avoidance behaviors (e.g., Shine, 1980; Hertz et al., 1982; Arnold, 1988). In some cases, predictions about effects of specific risk factors have been tested (e.g., Bulova, 1994; Burger and Gochfeld, 1990; Brafia, 1993). Antipredatory behavior has received the belated attention of optimality theorists only in recent years. Ydenberg and Dill (1986) developed a simple optimality model in which a prey's assessment of the degree of risk and the costs of fleeing determine how closely a prey allows a predator to approach before fleeing. Lima and Dill (1990) extended the optimality approach to several other components of predation risk. Clark (1994) emphasized that antipredatory decisions should be made based on consequences for long-term expected fitness, but predation risk typically has been and is here considered only in the context of probability of mortality in the immediate future.

Escape by a refuging prey, the broad-headed skink (Eumeces laticeps)

Factors influencing escape to refuge by the broad-headed skink (Eumeces laticeps) were examined by multiple regression and correlation of quantitative escape variables and distance and direction to refuge. I simulated a predator by walking toward a lizard and recorded aspects of escape. Approach distance (distance from me when escape began) increased with distance and angle to refuge, suggesting that the skinks assessed that risk increased with relative times required for prey and predator to reach the refuge. Distance fled was affected jointly by distance from the predator when escape began and distance to refuge; it increased with distance to refuge. It also increased with the angle between the predator's path and refuge due to declining distance from the predator per unit distance fled. Direction to the nearest refuge and direction fled were nearly identical. Distance and direction to refuge should strongly affect escape behaviour in prey that are active some distance from refuges but rely on them to avoid predation. These relationships may be weaker or absent in anachoric species (those nearly continuously occupying refuges) and those remaining close to refuges, as well as in species relying more on speed and fleeing for long distances than on refuges.

Maximizing male reproductive success in the broad-headed skink (Eumeces laticeps): preliminary evidence for mate guarding, size-assortative pairing, and opportunistic extra-pair mating

AbstractSeveral lines of evidence suggest that male Eumeces laticeps may increase reproductive success by 1) mating with larger females to increase clutch size, 2) mate guarding to be present during the female's receptive period and/or prevent sperm competition, and 3) engaging in extra-pair copulations. Clutch size increases with female body size, establishing a potential advantage of male preference for large female mates. Mate association lasts up to 8 days and possibly longer, with a mean of nearly 5 days. Males may remain with females during a major portion of the mating season, which preliminary data suggest lasts about two weeks, suggesting that mate-guarding may reduce the level of polygyny. Tethered introductions of intruder males to consort pairs showed that consort males use aggressive behavior to exclude other males from the vicinity of females. Eumeces laticeps exhibits strong positive size-assortative pairing, suggesting the possible importance of male choice of large mates. Female preference for large males could account for this relationship, but only if large females prefer the largest possible males within the acceptable size range and aggressively exclude other females from preferred males. Females are sometimes aggressive to each other, especially near nest sites, but aggression is suppressed by males, as shown by tethered introduction of females to consort pairs. Size-assortative pairing may be based in part on male preference if males can prevent larger females from aggressively excluding smaller ones. In addition to preferentially guarding large females, males not currently guarding mate with any females not large enough to deter them aggressively. A field observation of an extra-pair copulation, responses by consort males to introduced females, and the lack of size preference in the absence of consorts suggest that males may engage opportunistically in extra-pair copulations to increase reproductive success and are not then choosy about female size.

Chemosensory Recognition of Familiar and Unfamiliar Conspecifics by the Scincid Lizard Eumeces laticeps

AbstractThe ability of broad‐headed skinks (Eumeces laticeps) to distinguish familiar from unfamiliar individuals of the opposite sex and themselves from other individuals of the same sex using only chemical stimuli was examined experimentally. Cloacal chemical stimuli were presented to lizards on moistened cotton swabs and numbers of tongue‐flicks performed in 60 s were recorded. Males emitted significantly greater numbers of tongue‐flicks in response to chemical cues from unfamiliar females than of female cagemates. Response rates of males housed with females and males housed alone to chemical stimuli from unfamiliar females did not differ. Chemical stimuli from unfamiliar males elicited significantly more tongue flicks from males than their own or deionized water, but their own stimuli elicited no more than the odourless control. Females tongue‐flicked significantly more in response to cloacal chemical stimuli from unfamiliar males than from male cagemates. The findings indicate that both sexes of broad‐headed skinks can discriminate between chemical stimuli of familiar and unfamiliar individuals of the opposite sex and that males can distinguish their own cloacal chemicals from those of unfamiliar males. The possible functions of these chemosensory capacities, including location of mates by scent‐trailing and assessment of the presence of sexual competitors, are discussed in relation to the social behaviour of E. laticeps.