Jacquelyn C. Guzy

Do Ponds on Golf Courses Provide Suitable Habitat for Wetland-Dependent Animals in Suburban Areas? An Assessment of Turtle Abundances

Abstract Golf courses represent a common type of anthropogenically modified habitat in suburban environments. Golf courses may provide suitable habitat for semi-aquatic animals in suburban areas, yet studies comparing animal abundances in golf course ponds with other pond types in suburban environments are somewhat limited. In this study, we compared turtle abundances in golf course ponds with ponds found in residential areas and ponds found in rural (farm) areas and examined the relationship between turtle abundance and residential land-cover within individual golf courses. We captured turtles in 10 golf course ponds, 5 ponds surrounded by residential development, and 5 ponds located on farms. We estimated abundance and the effects of pond area, pond type (i.e., residential, golf, farm) and percentage of residential development within golf course boundaries. Using binomial mixture models and Bayesian inference, we found that ponds surrounded by residential development had lower abundances of Painted Turtles (Chrysemys picta) and Sliders (Trachemys scripta) than ponds located on golf courses and farms. Additionally, golf courses that have a greater amount of residential development within course boundaries had fewer turtles than courses that contained minimal residential development. Our results suggest that golf courses can offer suitable habitat for semi-aquatic turtles in suburban areas. However, residential development within golf course boundaries appears to have a negative effect on local abundances. Thus, if golf courses are to be seen as reserves for wetland-dependent animals, golf courses with low housing density should be considered as a more preferable option than courses associated with extensive residential development.

Using multiple methods to assess detection probabilities of riparian-zone anurans: implications for monitoring

Abstract Context. Both manual call surveys (MCS) and visual encounter surveys (VES) are popular methods used to monitor anuran populations. Recent statistical developments, specifically the development of occupancy models that permit the use of data from various survey methods to assess method-specific detection probabilities, provide a rigorous framework for evaluating the effectiveness of field methods. Aim. To compare species-specific detection probabilities generated by MCS and VES and to evaluate the effectiveness of these methods throughout the activity season of several riparian-zone anuran species. Methods. During 2010 and 2011, we sampled 21 sites along the Broad and Pacolet Rivers, in South Carolina, USA, using MCS and VES. Anuran species were surveyed across three seasons (fall, spring and summer) each year. Key results. For six species, MCS resulted in a higher mean probability of detection, whereas VES resulted in a higher mean probability of detection for four species. In addition, survey date was an important influence on detection probability of most anurans when using MCS, but largely unimportant when employing VES. Conclusions. Our findings indicated that VES are as effective as MCS for detecting some species of anurans, and for others, VES represent a more effective method. Furthermore, when using VES outside the breeding window, some anurans can be reliably detected, and in some cases, detected more easily than by using MCS. Implications. We suggest that VES is a complimentary technique to MCS and a potentially important tool for population monitoring of anurans. VES can provide more flexibility for anuran researchers, as robust estimates of detection and occupancy can be obtained outside a narrow breeding window.

Sexual Dimorphism and Feeding Ecology of Diamond-backed Terrapins (Malaclemys terrapin)

Abstract:  Natural and sexual selection are frequently invoked as causes of sexual size dimorphism in animals. Many species of turtles, including the Diamond-backed Terrapin (Malaclemys terrapin), exhibit sexual dimorphism in body size, possibly enabling the sexes to exploit different resources and reduce intraspecific competition. Female terrapins not only have larger body sizes but also disproportionately larger skulls and jaws relative to males. To better understand the relationship between skull morphology and terrapin feeding ecology, we measured the in-lever to out-lever ratios of 27 male and 33 female terrapin jaws to evaluate biomechanics of the trophic apparatus. In addition, we measured prey handling times by feeding Fiddler Crabs (Uca pugnax), a natural prey item, to 24 terrapins in the laboratory. Our results indicate that although females have disproportionately larger heads, they have similar in:out lever ratios to males, suggesting that differences in adductor muscle mass are more important in determining bite force than jaw in:out lever ratios. Females also had considerably reduced prey handling times. Understanding the factors affecting terrapin feeding ecology can illuminate the potential roles male and female terrapins play as top-down predators that regulate grazing of Periwinkle Snails (Littorina irrorata) on Cord Grass (Spartina alterniflora).

Oviposition Site Selection by Spotted Salamanders (Ambystoma maculatum) in an Isolated Wetland

Abstract Oviposition site selection is an important aspect of reproduction for species such as amphibians that breed in dynamic environments. We examined predictors of oviposition site selection of Spotted Salamanders (Ambystoma maculatum) at Cowans Ford Wildlife Refuge in Mecklenburg County, North Carolina. We conducted egg mass surveys and checked 40 minnow traps for potential predators every 2 days along transects, sampling a subset of all representative habitat within the wetland. Random points were generated for each egg mass to compare microhabitat conditions in areas where egg masses were present versus undetected. We constructed a paired logistic regression model and used Akaike information criterion to rank the associations between oviposition site and water depth, temperature, predator density, and vegetation. Ambystoma maculatum egg mass location was best predicted by deeper water and denser submergent vegetation. Our study suggests that A. maculatum select oviposition sites actively, rather than ovipositing in all available microhabitat, implying that vegetation structure and hydrology of ephemeral wetlands are important for the successful reproduction of this species.

Temporal and Spatial Variation in Survivorship of Diamondback Terrapins (Malaclemys terrapin)

Abstract The diamondback terrapin (Malaclemys terrapin) is a species of conservation concern that has experienced noticeable declines throughout its range. Mark–recapture studies have been conducted on terrapins at Kiawah Island, South Carolina, since 1983, and during the early 1990s, this population began to decline. Our objectives were to evaluate current spatial and temporal variation in survivorship and compare current estimates of survivorship with those calculated from 1983 to 1999 in a previous study. We used an 11-year data set (2003 to 2013) in a capture–mark–recapture analysis to estimate the survivorship of terrapins in 5 creeks. Among creeks, annual survivorship estimates ranged from 61% to 82% with no difference between the sexes. Survivorship was lower than that documented for this population in the early 1990s. Recent anthropogenic habitat modification, such as the construction of docks, roads, and housing developments, as well as activities such as crab-trapping, likely play a role in low annual survivorship. Results from this long-term study are essential for understanding terrapin population status and can inform conservation and coastal ecosystem management.

Herpetofaunal Communities in Restored and Unrestored Remnant Tallgrass Prairie and Associated Wetlands in Northwest Arkansas, USA

Wetlands within tallgrass prairie are among the most endangered ecosystems in North America and serve as critical habitat for many sensitive and endemic species. Although loss of these habitats has acutely affected reptiles and amphibians, most prairie restoration initiatives take an ecosystem restoration approach adapted for plant and/or game species, with few focusing particularly on herpetofauna. Limited information exists documenting the population responses of reptiles and amphibians to wetland restoration in tallgrass prairie ecosystems. We used multiple techniques to compare reptile and amphibian communities in recently (2006) restored and unrestored tallgrass prairie and associated wetland habitats at Woolsey Wet Prairie Sanctuary (WWPS), a wetland mitigation site in Northwest Arkansas (USA). We documented 24 reptile and amphibian species and found that Regina grahamii (Graham’s Crayfish Snake) and Lithobates areolatus (Crawfish Frog), both of which are considered species of greatest conservation need in the state, showed preferential use of restored habitat, while common, widespread species did not use restored or unrestored habitat preferentially. Our results demonstrate that restoration of tallgrass prairie and associated wetlands benefits rare and sensitive herpetofauna and highlight two important management considerations: 1) promoting ephemeral (fishless) hydrology, and 2) emphasizing terrestrial movement corridors and critical upland habitat.

Influence of damming on anuran species richness in riparian areas: A test of the serial discontinuity concept

Abstract Almost all large rivers worldwide are fragmented by dams, and their impacts have been modeled using the serial discontinuity concept (SDC), a series of predictions regarding responses of key biotic and abiotic variables. We evaluated the effects of damming on anuran communities along a 245‐km river corridor by conducting repeated, time‐constrained anuran calling surveys at 42 locations along the Broad and Pacolet Rivers in South Carolina, USA. Using a hierarchical Bayesian analysis, we test the biodiversity prediction of the SDC (modified for floodplain rivers) by evaluating anuran occupancy and species diversity relative to dams and degree of urbanized land use. The mean response of the anuran community indicated that occupancy and species richness were maximized when sites were farther downstream from dams. Sites at the farthest distances downstream of dams (47.5 km) had an estimated ~3 more species than those just below dams. Similarly, species‐specific occupancy estimates showed a trend of higher occupancy downstream from dams. Therefore, using empirical estimation within the context of a 245‐km river riparian landscape, our study supports SDC predictions for a meandering river. We demonstrate that with increasing distance downstream from dams, riparian anuran communities have higher species richness. Reduced species richness immediately downstream of dams is likely driven by alterations in flow regime that reduce or eliminate flows which sustain riparian wetlands that serve as anuran breeding habitat. Therefore, to maintain anuran biodiversity, we suggest that flow regulation should be managed to ensure water releases inundate riparian wetlands during amphibian breeding seasons and aseasonal releases, which can displace adults, larvae, and eggs, are avoided. These outcomes could be achieved by emulating pre‐dam seasonal discharge data, mirroring discharge of an undammed tributary within the focal watershed, or by basing real‐time flow releases on current environmental conditions.

Distribution and Abundance of Introduced Seal Salamanders (Desmognathus monticola) in Northwest Arkansas, USA

Many reptiles and amphibians are gaining recognition as harmful invaders, highlighted by well-known examples such as the Brown Tree Snake (Boiga irregularis), Cane Toad (Rhinella marina), American Bullfrog (Lithobates catesbeianus), and Burmese Python (Python molurus bivittatus). In 2003, an introduced population of Seal Salamanders (Desmognathus monticola) was found in Spavinaw Creek, within the Ozark Plateau of northwest Arkansas. Genetic evidence confirmed an introduction from northern Georgia. Very little is known about the status of this non-native population; thus, the objective of this study was to assess the current distribution and abundance of non-native D. monticola along Spavinaw Creek. We conducted repeated, low-intensity visual surveys along the 30 km extent of Spavinaw Creek in Arkansas and used a hierarchical Bayesian analysis to model the occupancy response of D. monticola and five native salamander species relative to river mile and habitat covariates. We also conducted a short-term closed capture-mark-recapture study to estimate abundance of D. monticola at the original collection site on Spavinaw Creek. We found a clear geographic pattern of distribution of D. monticola, with individuals found throughout the upper 10 km of Spavinaw Creek headwaters, but no clear habitat associations. Estimated abundance of D. monticola was extremely high—14.5 individuals and 50 g wet biomass per m2. Our results reveal that introduced D. monticola are much more widely distributed than previously recognized and occur at high densities, suggesting that this recent invader could negatively affect ecosystems of Spavinaw Creek and surrounding watersheds in the Ozark highlands.

Riparian-Zone Amphibians and Reptiles Within the Broad River Basin of South Carolina

Abstract An inventory of the Broad River Basin in South Carolina documented distribution and species richness of amphibians and reptiles of the area, focusing primarily on riparian zones. A list of 92 potentially occurring species was assembled for the area. Multiple survey methods were used including active searches, manual anuran calling surveys, and turtle trapping to document the herpetofauna. Using these techniques, 14 anuran, 9 salamander, 7 lizard, 16 snake, and 8 turtle species were documented. Seven of these species were of conservation concern in South Carolina. The Broad River Basin supports a diverse array of amphibian and reptile species associated with both wetland and riverine habitats. As water resources, energy demand, and urbanization continue to increase in the Piedmont region, these baseline data have important implications for conservation and future land management.