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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Status of a Translocated Florida Sand Skink Population After Six Years: Establishing and Evaluating Criteria for Success

Emerick, Adam Ryan 30 January 2015 (has links)
The translocation of organisms is becoming a frequently used tool in conservation biology. There are, however, a disproportionate number of unsuccessful attempts translocating populations of herpetofauna. Logistical and temporal limits of monitoring, combined with ambiguous metrics concerning "success," have led to few advances regarding reptile translocations. Successfully established and persistent populations are those in which both the founding population and subsequent generations show consistent or positive levels of survival and reproduction. A small population of the threatened Florida Sand Skink (Plestiodon reynoldsi) was translocated in 2007. Data collected from 2007 to 2009 confirmed survival and reproduction among the founding individuals, but the sampling did not include a long enough period to allow for the evaluation of the survival and reproduction of individuals born on the site. In this study, individuals were collected during two separate sampling events, one during the third spring and one during the sixth spring after the translocation occurred. Survival estimates, reproduction, population size and generation structure were calculated by combining and analyzing data from all years post-translocation. The numbers of both total and new individuals captured in the sixth year exceeded captures from every prior sampling event since monitoring began in 2008. Founding individuals represented only 14% of the total individuals captured, while the number of individuals born on site continued to increase. The proportion of recruits and increased number of hatchlings despite the loss of founders shows that the filial generations are producing offspring. The methods utilized in assessing this translocation effort will further the understanding of the population dynamics of the Florida Sand Skink and allow for more informed decisions in future management studies of this threatened species.
2

Microhabitat preferences of the prairie skink (Plestiodon septentrionalis) in southwestern Manitoba

Larkin, Jill A. 11 April 2011 (has links)
In Canada, the endangered prairie skink (Plestiodon septentrionalis) exists only in southwestern Manitoba. Habitat loss is the most significant threat faced by the prairie skink in Canada, with leafy spurge (Euphorbia esula) invasion identified as one of the suspected factors contributing to habitat loss. The objectives of this study were to determine microhabitat preferences and effect of leafy spurge on prairie skinks in southwestern Manitoba. To determine microhabitat preferences, occupied sites were compared to unoccupied sites. Artificial cover was identified as the most important microhabitat element. To determine the impacts of spurge on microhabitat, ground temperatures in invaded were compared to un-invaded sites. No significant differences in temperature or skink density were observed between invaded and un-invaded site; however, skinks were more likely to use spurge when cover was present, than when no cover was present. Artificial cover may improve microhabitat by providing refuge from predators and microhabitat for prey.
3

Microhabitat preferences of the prairie skink (Plestiodon septentrionalis) in southwestern Manitoba

Larkin, Jill A. 11 April 2011 (has links)
In Canada, the endangered prairie skink (Plestiodon septentrionalis) exists only in southwestern Manitoba. Habitat loss is the most significant threat faced by the prairie skink in Canada, with leafy spurge (Euphorbia esula) invasion identified as one of the suspected factors contributing to habitat loss. The objectives of this study were to determine microhabitat preferences and effect of leafy spurge on prairie skinks in southwestern Manitoba. To determine microhabitat preferences, occupied sites were compared to unoccupied sites. Artificial cover was identified as the most important microhabitat element. To determine the impacts of spurge on microhabitat, ground temperatures in invaded were compared to un-invaded sites. No significant differences in temperature or skink density were observed between invaded and un-invaded site; however, skinks were more likely to use spurge when cover was present, than when no cover was present. Artificial cover may improve microhabitat by providing refuge from predators and microhabitat for prey.
4

Long-term effects of prescribed fire on reptile and amphibian communities in Florida sandhill

Halstead, Neal Thomas 01 June 2007 (has links)
I examined the effects of fire frequency on reptile and amphibian community composition in a periodically burned sandhill habitat in west-central Florida. Plots burned in 2003 had lower species richness, diversity, and evenness indices than plots that had not been burned during the previous six years. Community composition was different among plots burned at different times and followed a gradient of change that corresponded to the time since the last fire. Aspidoscelis sexlineata were the most abundant lizards in recently burned plots, while Scincella lateralis and Plestiodon inexpectatus were relatively more abundant in unburned plots. Gopherus polyphemus were least abundant in unburned plots. Community composition among plots was correlated with mean leaf litter cover and herbaceous ground cover. Mean percent cover of leaf litter and herbaceous vegetation responded to the time since the last fire. Fire indirectly affects community composition through changes in environmental variables, such as percent coverage of leaf litter and herbaceous vegetation.Additionally, I examined annual variation in reptile and amphibian community composition over a period of four years in the mid 1980s and again in 2004. Differences existed in number of individuals captured, diversity, and evenness among years. Community composition was different between all consecutive years except 1986 and 1987. Number of individuals captured per year and annual differences in community composition were correlated with summer rainfall. The annual pattern of variation in community composition over time was no different in unburned experimental plots than in experimentally burned treatments. The power to detect such a difference is low, however, because of low replication. No apparent loss of species occurred between the 1980s and 2004, but the abundances of two non-native species were significantly higher in 2004 than in the 1980s. A third exotic species was documented at the site for the first time in 2004. Because of the increasing number of exotic reptiles and amphibians in Florida, the site is at risk of invasions of other species.

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