Jeffrey E. Lovich

Age at maturity influences adult sex ratio in the turtle Malaclemys terrapin

Numerous explanations have been offered for biased sex ratios including sampling bias, skewed primary sex ratios, differential mortality, differential immigration and emigration, and differential maturity of the sexes. We observed a strongly malebiased population of the turtle Malaclemys terrapin in South Carolina, USA. The overall adult male:female sex ratio was 1.78: 1. Although males predominated numerically, the probability of recapturing individuals of either sex was the same (0.44 for males, 0.38 for females). Sex ratios were consistently male biased when based on monthly and yearly samples. This bias was not altered by the use of different collecting techniques or restriction of the sample to major habitats within the study area. Previously reported adult sex ratios for other populations range from strongly male biased to strongly female biased. Reports of female-biased samples appear to be a result of sampling bias or the artificial conditions under which terrapins have been cultivated in the past. The excess of males in our population appears to be a result of differences in the timing of maturity between the sexes. Male Malaclemys mature after their third year and females after their sixth year. Assuming a minimal effect from the other potential factors and regular juvenile recruitment, we expect that male Malaclemys will maintain numerical superiority in most populations. We propose that adult sex ratio variation in turtles, and other organisms with sexual differences in the timing of maturity, can be explained with a simple model: the earlier maturing sex will predominate numerically.

Wildlife Conservation and Solar Energy Development in the Desert Southwest, United States

Large areas of public land are currently being permitted or evaluated for utility-scale solar energy development (USSED) in the southwestern United States, including areas with high biodiversity and protected species. However, peer-reviewed studies of the effects of USSED on wildlife are lacking. The potential effects of the construction and the eventual decommissioning of solar energy facilities include the direct mortality of wildlife; environmental impacts of fugitive dust and dust suppressants; destruction and modification of habitat, including the impacts of roads; and off-site impacts related to construction material acquisition, processing, and transportation. The potential effects of the operation and maintenance of the facilities include habitat fragmentation and barriers to gene flow, increased noise, electromagnetic field generation, microclimate alteration, pollution, water consumption, and fire. Facility design effects, the efficacy of site-selection criteria, and the cumulative effects of USSED on regional wildlife populations are unknown. Currently available peer-reviewed data are insufficient to allow a rigorous assessment of the impact of USSED on wildlife.

The Use of Coverboards in Estimating Patterns of Reptile and Amphibian Biodiversity

Reptiles and amphibians play important roles in ecological communities and can be extremely sensitive indicators of environmental change, despite their cryptic and secretive habits. To estimate herpetofaunal community dynamics potentially attributable to either natural or anthropogenic environmental variation, herpetofaunal biodiversity managers will require specific, standardized, and efficient field sampling methods. One such method involves using arrays of wood and tin coverboards and is the subject of this paper. Studies were conducted on the Savannah River Site in the Upper Coastal Plain of South Carolina from January 1988 to August 1991. Compared with a drift fence/pitfall trap array, the coverboard technique requires less maintenance and sampling effort, but only those reptiles and amphibians using the coverboards at the time of an array check could be encountered. In contrast, live-trapping methods integrate over a longer time period and thereby generate many more encounters per trap. Nonetheless, large numbers of encounters with cryptic reptiles and amphibians can result from coverboard sampling depending upon the study site, coverboard age, time of day, and type of coverboard (i.e., wood or tin). Detailed analyses of hydric and thermal microclimates beneath coverboards suggest specific mechanisms to explain observed differences in herpetofaunal coverboard use. We conclude that the coverboard technique can provide a useful means to quantify patterns in herpetofaunal relative abundance and biodiversity. However, array design and sampling protocol should be carefully selected to minimize sampling biases in encounter probabilities due to subtle differences among herpetofauna in their hygrothermal microclimate preferences.

Geographic Variation in Growth and Sexual Size Dimorphism of Bog Turtles (Clemmys muhlenbergii)

Abstract We examined sexual size dimorphism (SSD) and growth rates in samples of bog turtles (Clemmys muhlenbergii) from North Carolina, Pennsylvania and New Jersey. Mean carapace length (CL) of males was significantly greater than mean CL of females in all three states. However, the degree of SSD varied significantly among states. Specimens from North Carolina had the greatest SSD, the largest mean adult CL, and the largest mean hatchling CL. Growth rates were rapid until about age 6 and a CL of 80 mm. Males grew faster than females thereafter. A comparison of the three parameters estimated from von Bertalanffy growth equations showed significant differences for asymptotes between sexes and states for the North Carolina and Pennsylvania samples, but not for the growth rate constant (parameter k). Geographic variation in SSD appears to be a result of differences in growth related to the timing of maturity and the approach to asymptotic body size caused by indeterminate growth, or both. We suggest that male-biased SSD in this species is ultimately a consequence of the advantage conferred to larger males in male-male interactions and during mating.

Nesting Ecology of a Population of Gopherus agassizii at a Utility-Scale Wind Energy Facility in Southern California

We investigated the annual nesting ecology of a population of Desert Tortoises (Gopherus agassizii) inhabiting a utility-scale renewable energy (USRE) facility in southern California and compared our results with populations inhabiting relatively undisturbed sites. In 2000, 15 radio-tracked females produced 29 clutches, and 24 nests were monitored to examine nest-site selection, nest predation, hatching success, date of emergence of hatchlings, and hatchling mass and carapace length. Overall, the nesting ecology of the population inhabiting the USRE facility was very similar to other populations of Desert Tortoises inhabiting relatively undisturbed habitats. Oviposition occurred from 12 May to 8 July, which was similar to other sites. Nest depths (11.1 cm), nest predation (12%), hatchling emergence date (7 August and 29 September), and hatchling morphometrics (i.e., MCL: 44.5 mm; mass: 23 g) were all within ranges reported in other populations. Unlike within other populations, we observed no relationship between hatchling size and either maternal body size or egg width. We found no evidence of females selecting for a particular burrow for oviposition of eggs based on environmental or anthropogenic variables. Most nests were located in or near burrows, and nest depth was greater for nests near the entrance than those deeper in the burrow. Although this study suggests that the nesting ecology of the Desert Tortoise population we studied was not adversely affected by the USRE facility, this relationship is only correlative because our study was not a before-after-control-impact (BACI) study, which would establish a cause and effect relationship. As pointed out in a recent review, BACI studies are critically needed to address the wildlife impacts of utility-scale renewable energy development.

Turtles and Culverts, and Alternative Energy Development: An Unreported but Potentially Significant Mortality Threat to the Desert Tortoise (Gopherus agassizii)

Abstract Culverts are often used to increase the permeability of roaded landscapes for wildlife, including turtles. Although the benefits of culverts as safe passages for turtles are well documented, under some conditions culverts can entrap them and cause mortality. Here we report a culvert-related mortality in the federally threatened desert tortoise (Gopherus agassizii) at a wind energy facility in California and offer simple recommendations to mitigate the negative effects of culverts for wildlife in general.

Nest-Guarding by Female Agassiz's Desert Tortoise (Gopherus agassizii) at a Wind-Energy Facility Near Palm Springs, California

Abstract We observed behavior consistent with nest-guarding in Agassizs desert tortoise (Gopherus agassizii) at two nests in a large wind-energy-generation facility near Palm Springs, California, locally known as the Mesa Wind Farm. As researchers approached the nests, female desert tortoises moved to the entrance of their burrows and positioned themselves sideways, directly over their nests. One female stretched her limbs outward and wedged herself into the burrow (her plastron directly above the nest). Guarding of nests is rarely observed in Agassizs desert tortoise but can occur as a result of attempted predation on eggs by Gila monsters (Heloderma suspectum) or in direct response to the perceived threat posed by researchers. This is the first report of nest-guarding for G. agassizii in the Sonoran Desert ecosystem of California. Resumen Observamos el comportamiento de las tortugas del desierto (Gopherus agasiizii) que parece vigilar a sus nidos. Observamos este comportamiento en dos nidos que estuvieron ubicados en las instalaciones para la generación de energía eólica, cerca de Palm Springs, California, conocida localmente como Mesa Wind Farm. Cuando los investigadores se acercaron a los nidos, las tortugas hembras se desplazaron hacia la entrada de su madriguera y se posicionaron a los lados directamente sobre sus nidos. Una hembra estiró sus extremidades hacia fuera asegurándose ella misma dentro de la madriguera (dejando el plastrón directamente encima del nido). Es muy raro observar la vigilancia de nidos en las tortugas del desierto, pero puede ocurrir como resultado de intentos de depredación de huevos por el monstruo de Gila (Heloderma suspectum) o como respuesta directa al percibir a los investigadores como una amenaza. Este es el primer reporte del comportamiento de vigilancia de nidos de la tortuga G. agassizzi en California en el ecosistema del desierto de Sonora.

Geographic Variation in the Seasonal Activity Cycle of Spotted Turtles, Clemmys guttata

to northern Florida, and west through Pennsylvania and the lower Great Lakes region to northeastern Illinois (Ernst, 1972). Previous investigators have noted that northern populations of C. guttata are active primarily during the spring (Conant, 1951; Nemuras, 1966; Ernst, 1976), and appear to shun high environmental temperatures (Ward et al., 1976; Ernst, 1982). However, there are no published accounts regarding the seasonal activity cycle of this essentially northern species in the southern part of its range. If aversion to high temperature is consistent in the species, then turtles at lower latitudes should initiate their activity cycle earlier than populations at higher latitudes. The objective of this study was to compare the seasonal activity cycles of C. guttata from various geographic regions. Previously published seasonal activity cycles for C. guttata (Ohio-Conant, 1951; Maryland-Nemuras, 1966; Pennsylvania-Ernst, 1976) were compared, along with unpublished records for South Carolina. Records for South Carolina were based on live ani-

Geographic Variation in the Asiatic Turtle Chinemys reevesii (Gray) and the Status of Geoclemys grangeri Schmidt

The Chinese coin turtle Chinemys reevesii is widely distributed in eastern Asia from Japan to southern China. Within its range, three taxa have been described which are similar to C. reevesii except for minor differences (Geoclemys grangeri, Geoclemys paracaretta, and Damonia unicolor). Although these variants have been synonymized by some authors, no quantitative studies have been conducted to support or reject their validity. The present study examined 31 characters of specimens throughout the range. Analysis indicates that all variants are within the diagnostic extremes observed in this species. Low interpopulational variation in C. reevesii is due in part to several millennia of human disturbance.

Morphological and Molecular Reassessment of Graptemys oculifera and Graptemys flavimaculata (Testudines: Emydidae)

Abstract The turtle genus Graptemys consists of 15 recognized taxa, distinguished largely on the basis of pigmentation pattern (i.e., soft tissue and shell), head size, and shell morphology. However, phylogenetic studies have shown limited sequence divergence within the genus and between Graptemys oculifera and Graptemys flavimaculata relative to most other members of the Emydidae. Graptemys oculifera of the Pearl River drainage and G. flavimaculata of the Pascagoula River drainage have been recognized as species since 1890 and 1954, respectively. However, the description of G. flavimaculata was based on a limited number of morphological characters. Several of these characters overlap between G. flavimaculata and G. oculifera, and no attempt was made to test for significant morphological differentiation. In this study, we reevaluated the morphological and genetic distinctiveness of G. flavimaculata and G. oculifera with (1) multivariate statistical analyses of 44 morphological characters and (2) 1,560 bp of sequence data from two mitochondrial genes (control region and ND4). The morphological and molecular analyses produced incongruent results. The principal components analysis ordinations separated the two species along a pigmentation gradient with G. flavimaculata having more yellow pigmentation than G. oculifera. Likewise, clustering analyses separated the specimens into two distinct groups with little overlap between the species. Our mitochondrial data supported previous findings of limited genetic differentiation between the two species. However, the results of our morphological analyses, in conjunction with recently published nuclear gene sequence data, support the continued recognition of the two species.