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C.K. Dodd

Publications and source records attributed to C.K. Dodd.

At least 37 records · Page 2Linked to original sources
USGS2004

The effectiveness of a barrier wall and underpasses in reducing wildlife mortality on a heavily traveled highway in Florida

Because of high numbers of animals killed on Paynes Prairie State Preserve, Alachua County, Florida, the Florida Department of Transportation constructed a barrier wall-culvert system to reduce wildlife mortality yet allow for passage of some animals across the highway. During a one year study following construction, we counted only 158 animals, excluding hylid treefrogs, killed in the same area where 2411 road kills were recorded in the 12 months prior to the construction of the barrier wall-culvert system. Within the survey area lying directly in Paynes Prairie basin, mortality was reduced 65% if hylid treefrogs are included, and 93.5% with hylid treefrogs excluded. Sixty-four percent of the wildlife kills observed along the barrier wall-culvert system occurred at a maintenance road access point and along 300 m of type-A fence bordering private property. The 24 h kill rate during the post-construction survey was 4.9 compared with 13.5 during the pre-construction survey. We counted 1891 dead vertebrates within the entire area surveyed, including the ecotone between the surrounding uplands and prairie basin which did not include the barrier wall and culverts. Approximately 73% of the nonhylid road kills occurred in the 400 m section of road beyond the extent of the barrier wall-culvert system. We detected 51 vertebrate species, including 9 fish, using the 8 culverts after the construction of the barrier wall-culvert system, compared with 28 vertebrate species in the 4 existing culverts prior to construction. Capture success in culverts increased 10-fold from the pre-construction survey to the post-construction survey. Barrier wall trespass was facilitated by overhanging vegetation, maintenance road access, and by the use of the type-A fence. Additional problems resulted from siltation, water holes, and human access. These problems could be corrected using design modifications and by routine, periodic maintenance.

Biological Conservation↗
USGS2004

Using counts to simultaneously estimate abundance and detection probabilities in a salamander community

A critical variable in both ecological and conservation field studies is determining how many individuals of a species are present within a defined sampling area. Labor intensive techniques such as capture-mark-recapture and removal sampling may provide estimates of abundance, but there are many logistical constraints to their widespread application. Many studies on terrestrial and aquatic salamanders use counts as an index of abundance, assuming that detection remains constant while sampling. If this constancy is violated, determination of detection probabilities is critical to the accurate estimation of abundance. Recently, a model was developed that provides a statistical approach that allows abundance and detection to be estimated simultaneously from spatially and temporally replicated counts. We adapted this model to estimate these parameters for salamanders sampled over a six vear period in area-constrained plots in Great Smoky Mountains National Park. Estimates of salamander abundance varied among years, but annual changes in abundance did not vary uniformly among species. Except for one species, abundance estimates were not correlated with site covariates (elevation/soil and water pH, conductivity, air and water temperature). The uncertainty in the estimates was so large as to make correlations ineffectual in predicting which covariates might influence abundance. Detection probabilities also varied among species and sometimes among years for the six species examined. We found such a high degree of variation in our counts and in estimates of detection among species, sites, and years as to cast doubt upon the appropriateness of using count data to monitor population trends using a small number of area-constrained survey plots. Still, the model provided reasonable estimates of abundance that could make it useful in estimating population size from count surveys.

Herpetologica↗
USGS2004

Fluctuations in a metapopulation of nesting four-toed salamanders, Hemidactylium scutatum, in the Great Smoky Mountains National Park, USA, 1999-2003

We tested two predictions associated with the hypothesis that certain populations of pond-breeding amphibians are structured into metapopulations using minimum relative abundance estimates of nesting four-toed salamanders (Hemidactylium scutatum Schlegel) from 11 different ponds in the Great Smoky Mountains National Park. Coefficients of variation (CV) for counts at individual ponds ranged from 0.25 to 1.26, and the overall mean CV at all 11 ponds was 0.34. Many pairs of ponds had negative correlations in abundance from 1999-2003, whereas others had various degrees of positive correlation (mean r = 0.29). Thus, nesting population size fluctuated semi-independently among the ponds from year to year, inferring the existence of inter-pond dispersal. The mean number of nesting females at a pond was negatively, but non-significantly, correlated (r = -0.27; P = 0.40; 10 d.f.) to the pond's isolation. Owing to physiological constraints on plethodontid salamander energetics, precipitation during the nesting season (February and March) appeared to play an important role (r = 0.78; P = 0.12; 4 d.f.) in the number of nesting females we observed. Unlike some other plethodontid salamander populations in more fragmented southern Appalachian forest ecosystems, this (meta)population within Great Smoky Mountains National Park does not appear to be declining.

North carolina, Tennessee↗
USGS2003

Using ground-placed PVC pipes to monitor hylid treefrogs: Capture biases

We sampled a population of two species of hylid treefrogs using 90 vertical ground-placed PVC pipes of 3 diameters positioned along a 1500-m transect at a forest-open pond ecotone in north-central Florida in order to identify potential capture biases. We recorded 1,981 treefrog observations (778 unmarked, 1,203 recaptures) in 8 months. Our results identified species-specific seasonal and weather-related variation in capture by pipe diameter and pipe location. These biases may limit the usefulness of this sampling technique when monitoring long-term treefrog population status and trends.

Southeastern Naturalist↗
USGS2003

Estimation of Flattened Musk Turtle (Sternotherus depressus) survival, recapture, and recovery rate during and after a disease outbreak

We estimated survivorship, recapture probabilities and recovery rates in a threatened population of Flattened Musk Turtles (Sternotherus depressus) through a disease outbreak in Alabama in 1985. We evaluated a set of models for the demographic effects of disease by analyzing recaptures and recoveries simultaneously. Multiple-model inference suggested survival was temporally dynamic, whereas recapture probability was sex- and age-specifc. Biweekly survivorship declined from 98-99% before to 82-88% during the outbreak. Live recapture was twice as likely for male turtles relative to juveniles or females, whereas dead recoveries varied only slightly by sex and age. Our results suggest modest reduction in survival over a relatively short time period may severely affect population status.

Journal of Herpetology↗