Jacqueline D. Litzgus

Home Range and Seasonal Activity of Southern Spotted Turtles (Clemmys guttata): Implications for Management

Abstract Information about animal movement patterns is critical to understanding their ecology, and such information is essential to the design of conservation plans for threatened species. Using radio telemetry, GPS, and ArcView GIS software, we examined seasonal activity, habitat use, movements, and home-range size of a southeastern population of Spotted Turtles (Clemmys guttata), a declining species. Data collected over three years revealed an annually repeated pattern of seasonal activity. Habitat use differed annually, seasonally, and between the sexes. Home ranges overlapped, and there was an area of concentrated overlap in early spring, indicating an aggregation of turtles, likely for breeding. Individuals showed annual fidelity to home-range areas. Home-range size (calculated using three methods) for males was smaller (∼5 ha) than that of gravid females (∼16 ha). Movement data did not fully support the reproductive strategies hypothesis. As predicted, gravid females moved greater distances than males during the nesting season. In contrast to the hypothesis, males did not move their greatest distances in spring at which time mating mainly occurs. That males did not make the predicted movements in spring can be explained by the fact that turtles aggregated at this time of year; thus, males do not need to travel to find mates. The current study is important because it provides information on the role of natural (“hurricane-tip-ups”) and anthropogenic (powerline rights of way, clearcuts) disturbances in maintaining habitat heterogeneity and the early-successional vegetative communities preferred by Spotted Turtles. A set of management recommendations is presented.

Habitat selection by Blanding's turtles (Emydoidea blandingii) in a relatively pristine landscape

Abstract: Identifying habitats in which a species is likely to be found is extremely important for understanding the life history and general ecology of the species. Studies of habitat selection by species at risk provide information for management and recovery programs on critical habitat and are essential for conservation programs to be effective. Many studies on species at risk are conducted in highly altered or degraded habitats because few areas have not experienced human impacts. We investigated habitat selection by Blandings turtles (Emydoidea blandingii) in a large protected area, Algonquin Park. Specifically, we evaluated macrohabitat selection at 2 spatial scales (home range and individual location) and microhabitat selection at one scale. Macrohabitat selection was significant at the home range scale but not at the scale of individual location, and no shift in habitat selection was detected among different seasons. Habitat ranks were ambiguous because all wetland types were preferred over lotic and upland habitats. The microhabitat selection data showed no preference for habitat features or shifts among different seasons. These data combined with those from other studies suggest that large study sites in relatively pristine areas may include a large amount of suitable high-quality habitats such that habitat selection at a fine scale may not be detected or multiple habitat types may provide the resources necessary to support populations. Nomenclature: Ernst & Lovich, 2009.

Reproductive Output Depends on Body Condition in Spotted Turtles (Clemmys Guttata)

Abstract The body condition of an animal reflects its energetic state such that an animal in good condition has greater energy reserves than one that is in poor condition. Body condition in turn should be positively correlated with fitness because energetic reserves limit the amount of energy that can be allocated to reproduction. Using Spotted Turtles (Clemmys guttata) as a model system, and three years of field data from a South Carolina, USA population, we tested the prediction that reproductive output increases with maternal body condition. The effect of body condition on the reproductive output of female turtles was examined at three temporal scales (among clutches, among nesting seasons, and among females) using several variables including clutch frequency, clutch size, and multiple measures of egg size. We predicted that females in good condition will have a higher clutch frequency than those in poor condition; that females in good condition will have larger clutch sizes than those in poor condition; and that females in good condition will have larger eggs than those in poor condition. Among clutches and nesting seasons, we found no relationship between female body condition and reproductive output. Among females over the entirety of the three-year study, we found a positive relationship between body condition and clutch mass and egg size. In addition, females in poor condition and females in good condition both produced larger clutch sizes than females in intermediate condition. Our findings suggest that within a given reproductive bout and within a given reproductive season, energy reserves do not affect immediate reproductive investment. However, over the longer-term, females in good condition have greater reproductive output, which supports the idea of a bet-hedging life history strategy in turtles.

GEOGRAPHIC VARIATION IN REPRODUCTION IN A FRESHWATER TURTLE (CLEMMYS GUTTATA)

We examined reproduction over 3 yr using radio telemetry and X-rays in a South Carolina population of spotted turtles (Clemmys guttata). Spring courtship (March–April) coincided with aggregations of turtles; however, a second peak in courtship in the fall (September–October) did not coincide with such aggregations. Over 75% of the radio-tagged females were gravid in each year of the study. The nesting season lasted approximately two months (mid-May through mid-July). Nesting was primarily nocturnal, and most nests (17/21, 81%) were made in the woody debris of decaying logs and stumps. Incubation time (mean = 79 d) decreased as nest temperature increased. Clutch size was not correlated to maternal body size, and we found no evidence for a tradeoff between clutch size and egg size. However, all measures of egg size and most measures of hatchling size were independent of maternal body size. We also compared reproduction among three widely separated populations of spotted turtles. Clutch size varied with latitude: clutch size was largest in the north (Ontario, mean = 5.3 eggs), mid-sized in the central population (Pennsylvania, mean = 3.9), and smallest in the south (South Carolina, mean = 2.8). Variation in reproductive output among populations was attributable to both variation in number of eggs and to egg size. Most of this variation in clutch size and egg size was explained by differences in body size of females among populations. Because the spotted turtle is considered to be a Species at Risk throughout its range, the data provided in the current study will be useful in conservation planning and for directing future research on the reproductive ecology of freshwater turtles.

Mitigating Reptile Road Mortality: Fence Failures Compromise Ecopassage Effectiveness

Roadways pose serious threats to animal populations. The installation of roadway mitigation measures is becoming increasingly common, yet studies that rigorously evaluate the effectiveness of these conservation tools remain rare. A highway expansion project in Ontario, Canada included exclusion fencing and ecopassages as mitigation measures designed to offset detrimental effects to one of the most imperial groups of vertebrates, reptiles. Taking a multispecies approach, we used a Before-After-Control-Impact study design to compare reptile abundance on the highway before and after mitigation at an Impact site and a Control site from 1 May to 31 August in 2012 and 2013. During this time, radio telemetry, wildlife cameras, and an automated PIT-tag reading system were used to monitor reptile movements and use of ecopassages. Additionally, a willingness to utilize experiment was conducted to quantify turtle behavioral responses to ecopassages. We found no difference in abundance of turtles on the road between the un-mitigated and mitigated highways, and an increase in the percentage of both snakes and turtles detected dead on the road post-mitigation, suggesting that the fencing was not effective. Although ecopassages were used by reptiles, the number of crossings through ecopassages was lower than road-surface crossings. Furthermore, turtle willingness to use ecopassages was lower than that reported in previous arena studies, suggesting that effectiveness of ecopassages may be compromised when alternative crossing options are available (e.g., through holes in exclusion structures). Our rigorous evaluation of reptile roadway mitigation demonstrated that when exclusion structures fail, the effectiveness of population connectivity structures is compromised. Our project emphasizes the need to design mitigation measures with the biology and behavior of the target species in mind, to implement mitigation designs in a rigorous fashion, and quantitatively evaluate road mitigation to ensure allow for adaptive management and optimization of these increasingly important conservation tools.

Patterns of Maternal Investment in Spotted Turtles (Clemmys guttata): Implications of Trade-Offs, Scales of Analyses, and Incubation Substrates

Abstract: To maximize potential fitness, reproductive females should invest available resources in either larger propagules (egg and/or hatchling size) or more propagules (clutch size). Females may also enhance offspring performance by selecting nest sites with optimal conditions for the developing eggs. This study examined maternal investment in a population of spotted turtles (Clemmys guttata) in Ontario, Canada over 2 y using radio telemetry, x-ray photography, and indirect assessments of hatchling fitness. Analyses were conducted at 2 scales (clutch and female), utilizing 2 measures of available resources (body size and body condition). Larger females produced wider eggs, and similarity in the slopes of egg width and maternal pelvic aperture on body size may indicate a physical constraint on egg size. However, body size did not explain variation in egg morphometrics (length, width, or mass) when considering the reproductive output of each female over the entire study. Instead, females in better body condition produced more eggs. With respect to nest site selection, no selection for thermal properties was observed, and females exhibited stronger fidelity to nest substrates than to nest locations. Hatchling righting response was not related to hatchling body size or condition, but hatchlings from a clutch performed similarly, indicating maternal genetic effects or an effect of nest conditions. Thus, females in good condition maximize the number of eggs produced over multiple years, and hatchling morphometrics may not directly influence hatchling success. Nomenclature: Ernst & Lovich, 2009.

Spatial Ecology and Population Genetics of Northern Map Turtles (Graptemys geographica) in Fragmented and Continuous Habitats in Canada

Abstract In riverine systems, the construction of locks and dams may present barriers to movement for aquatic organisms and effectively fragment otherwise continuous populations. We examined the spatial ecology and population genetics of northern map turtles (Graptemys geographica) in the Trent-Severn Waterway (TSW), Ontario, Canada. We hypothesized that the locks and dams on the TSW are fragmenting map turtle habitats and creating barriers to movement, and predicted that turtles from fragmented habitats have significantly reduced home range sizes and daily movements compared to turtles from unfragmented habitats, and that populations on either side of a lock and dam would be genetically distinct. Home ranges and average daily movements were smaller for turtles from fragmented habitats compared with continuous habitats, indicating that locks and dams are restricting mobility. However, populations in fragmented habitats showed none of the predicted genetic consequences of fragmentation (e.g., reduced heterozygosity and allelic richness, differentiation across a barrier). Genetic data may be reflecting historic population structure because only a few turtle generations have passed since the construction of the locks and dams about 100 years ago. Additionally, our genetic data may not be sufficiently robust to detect differentiation at this relatively small geographic scale. Our study highlights the conservation importance of examining multiple facets of a single potential threat, especially for long-lived species that may show differences in short- and long-term effects of fragmentation.

Multiple Clutching in Southern Spotted Turtles, Clemmys guttata

Abstract We examined the reproductive output of spotted turtles (Clemmys guttata) from a population in South Carolina. We used radio telemetry, palpation, and x-rays to monitor the reproductive condition of females over two field seasons. We present the first evidence for multiple clutching in a wild population of spotted turtles. Of 12 females with radio transmitters that became gravid, five produced second clutches, and one produced a third clutch. Average annual clutch frequency was 1.2 per female. Clutch frequency was independent of body size. We compared reproductive output among three populations: Ontario, Pennsylvania, South Carolina. Individual clutch sizes varied with latitude. Clutch size was largest in the north (mean = 5.3 eggs), midsized in the central population (3.9), and smallest in the south (2.9). We suggest that this pattern is related to seasonality differences, which result in different selective pressures on body size of females. Total annual egg production (the sum of all clutches within a reproductive season) by gravid females did not differ between the Ontario (5.3 eggs) and South Carolina populations (4.6). These data indicate that, although individual clutch sizes differ between northern and southern spotted turtles, total annual reproductive output is consistent in these widely separated populations.

Cold‐Hardiness and Evaporative Water Loss in Hatchling Turtles

North American turtles hatch in late summer and spend their first winter either on land or underwater. Adaptations for terrestrial overwintering of hatchlings in northern regions, where winter thermal and hydric regimes are harsh, have not been systematically investigated in many species. We measured intrinsic supercooling capacity, resistance to inoculative freezing, and desiccation resistance in hatchlings of terrestrial and aquatic turtles collected from northern (Terrapene ornata, Chrysemys picta bellii, Kinosternon flavescens, Chelydra serpentina) and southern (Chrysemys picta dorsalis, Trachemys scripta, Sternotherus odoratus, Sternotherus carinatus) locales. Supercooling capacity was estimated from the crystallization temperature of turtles cooled in the absence of external ice nuclei. Mean values ranged from −8.1° to −15.5°C and tended to be lower in terrestrial hibernators. Inoculation resistance was estimated from the crystallization temperature of turtles cooled in a matrix of frozen soil. These values (range of means: −0.8° to −13.6°C) also tended to be lower in the terrestrial hibernators, especially C. picta bellii. Mean rates of evaporative water loss varied markedly among the species (0.9–11.4 mg g−1 d−1) and were lowest in the terrestrial hibernators. Most species tolerated the loss of a modest amount of body water, although half of the sample of S. carinatus died from desiccation. In general, turtles did not regain lost body water from wet soil, and immersion in free water was required for rehydration. Therefore, desiccation resistance may be an important adaptation to terrestrial hibernation. Resistances to inoculative freezing and desiccation were directly correlated, perhaps because they are governed by the same morphological characteristics.

Demography of a Southern Population of the Spotted Turtle (Clemmys guttata)

Abstract The Spotted Turtle (Clemmys guttata) is declining throughout its range in eastern North America as a result of habitat loss and collection for the pet trade. Although the species has been relatively well-studied in the northern part of its range, little is known about southern populations. We conducted a four-year study on a population of Spotted Turtles in South Carolina. A total of 44 turtles were captured: 21 females, 17 males, 5 juveniles, and 1 hatchling. There was no size dimorphism with respect to carapace length. However, females had longer plastrons, greater shell heights, and heavier body masses than males, likely as a result of the concavity of the male plastron. The adult sex ratio did not differ from 1:1. Estimated adult population size varied annually from 31 to 36 turtles, and density was estimated at 0.36 turtles/ha. This information is important for the creation of management plans to conserve populations across the Spotted Turtles range.