177 research outputs found
Reproductive Characteristics of South Florida Sternotherus odoratus and Kinosternon baurii (Testudines: Kinosternidae)
SNAKE ASSEMBLAGE STRUCTURES AND SEASONAL ACTIVITY PATTERNS ON A MILITARY BASE IN SOUTH-CENTRAL PENNSYLVANIA:: LAND MANAGEMENT IMPLICATIONS FOR SNAKE CONSERVATION
We ascertained the assemblage structures of snakes occurring in a mixed habitat matrix of natural and disturbed habitats during 2008–2011 at Letterkenny Army Depot (LEAD), a 7200 ha U.S. Army base in south-central Pennsylvania, to understand the patterns of species abundance as they related to habitat type of managed lands. We detected eight species in 12 sites comprising natural and disturbed habitats of wetlands, forest, and thicket and open fields. The Common Gartersnake (Thamnophis sirtalis) occurred in the most sites, the Red-bellied Snake (Storeria occipitomaculata) was the rarest species in the study. Two to six species occupied each site and were distributed unevenly. Dynamics of assemblages could be explained in part by habitat and also by the presence of the North American Racer (Coluber constrictor). All species for which data were available exhibited a unimodal pattern to their seasonal activity (mostly May and June); however, seasonal activity peaks differed between sexes. Sex ratios varied among species but were consistently female–biased in the Common Gartersnake and Ring-necked Snake (Diadophis punctatus) in Pennsylvania and surrounding areas. As elsewhere in Pennsylvania and the Northeast, body sizes of adults were larger for species syntopic with the North American Racer than for species not syntopic with this potential predator. We found a degree of predictability with respect to snake assemblage dynamics among habitats at LEAD, which in turn can prove useful in resource management of this large and protected human-impacted system
GEOGRAPHIC VARIATION IN SELECTED LIFE HISTORY TRAITS OF THE EASTERN NARROWMOUTH TOAD, GASTROPHRYNE CAROLINENSIS (HOLBROOK, 1836), ALONG THE NORTHEASTERN EDGE OF ITS GEOGRAPHIC RANGE
We examined the Eastern Narrowmouth Toad,Gastrophryne carolinensis, along the northeastern edge of its geographic range in Virginia to determine the extent to which selected life history traits in this region adhered to patterns associated with a latitudinal gradient in this species. As in studies elsewhere, a significant difference in mean adult body size between males (28.3 mm SVL) and females (30.1 mm SVL) was typical of this species as was the absence of a relationship between clutch size and female body size. Mean body sizes of both sexes appeared larger in northern populations than southern counterparts. Geographically predictable, the breeding season in Virginia was severely curtailed in response to climatic constraints despite extended fertility, and its breeding activity peaked in mid-summer as it has been reported to do throughout its geographic range. Thus, along the northern edge of its geographic range, the Eastern Narrowmouth Toad retains its ability breed for a longer season despite present climatic constraints, an advantage in the face of climate change that could alter timing and duration of acceptable breeding atmospheric conditions
Correction: Reproductive characteristics of South Florida Sternotherus odoratus and Kinosternon baurii (Testudines: Kinosternidae)
SEASONAL INCIDENCE OF CAPTURE AND REPRODUCTION OF FIVE FOSSORIAL SNAKE SPECIES IN WEST VIRGINIA
Museum specimens of five species of fossorial snakes collected in West Virginia during 1930–2000 were examined to determine monthly incidence of capture, adult body sizes, reproductive cycle, and clutch characteristics. Captures occurred over the shortest time in the year in the Eastern Earthsnake (Virginia valeriae valeriae) and Northern Red-bellied Snake (Storeria occipitomaculata occipitomaculata) and were longest in the Northern Brownsnake (S. dekayi dekayi). Male gonadal cycle conformed to the temperate pattern, whereas that of females tended towards a tropical pattern. Incidence of females nearing oviposition or parturition was highest during June–July for all species, and length of their reproductive seasons were generally in keeping with those of northerly populations of the respective species. Mean clutch sizes were largest in the Northern Brownsnake (mean = 20.5) and smallest in the single oviparous snake, the Eastern Wormsnake (mean = 2.8). Adult body sizes were similar to respective populations elsewhere within their ranges. The Mountain Earth Snake (V. pulchra) was the least represented species in this study. A meaningful degree of predictability existed in the life history traits examined in our study as they related to geographic trends of this Allegheny snake assemblage
Clutch Sizes in Two Populations of the Eastern Garter Snake (Thamnophis sirtalis) in Pennsylvania
THE NATURAL HISTORY OF THE NORTHERN BLACK RACER (COLUBER CONSTRICTOR CONSTRICTOR) IN SOUTH-CENTRAL PENNSYLVANIA
Long-term species surveys are effective tools for identifying changes in population demography which is of particular importance for those in threatened habitats such as grasslands. Due to their cryptic nature, snakes can benefit greatly from these types of surveys but multiyear surveys for snakes are rare in Pennsylvania and the surrounding region. We conducted coverboard surveys of the grassland specialist Northern Black Racer (Coluber constrictor constrictor) over eight years separated into two sampling periods (2008-2012 and 2015-2017) across a habitat-mosaic in south-central Pennsylvania. We recorded information on their body size, demography, and monthly activity. We compared these traits between the sampling periods to determine how they vary over time. A total of 70 Northern Black Racers were captured during this project. As expected, grasslands were heavily exploited by Northern Black Racers highlighting their importance to this species. There was a shift from relatively larger-bodied, older individuals towards relatively smaller-bodied, younger individuals between the sampling periods, but the sex ratio remained unchanged. Monthly activity of adults was unimodal in both sampling periods, but the month of peak activity varied and there was a possible effect of precipitation on this difference. The change in age structure between the sampling periods suggested that a widespread mortality event, possibly from exceedingly cold overwintering conditions, may have culled older individuals resulting in a younger cohort to fill the void. As Northern Black Racers are an important grassland predator, our data show the benefits of long-term surveys through detecting changes in demographics that could potentially influence long-term survival of a population
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