Basking dynamics among sympatric turtle species (Trachemys scripta elegans, Pseudemys texana, and Graptemys pseudogeographica kohnii) in Waco Creek, Texas.
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Worldwide access.Access changed 12/22/15.
Date
2013-09-24Author
Bardwell, Jeff H.
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The premise of this manuscript condenses into three words: turtles on logs.
Turtles splaying their limbs and sunning themselves on emergent deadwood is commonly
known as basking. Basking involves ectotherms taking advantage of solar radiation to
boost their core temperature and fuel metabolic processes. This study examines a
community assemblage of three turtle species within the Family Emydidae—Trachemys
scripta elegans: Red-eared Slider, Pseudemys texana: Texas River Cooter, and
Graptemys pseudogeographica kohnii: False Map Turtle—in Waco Creek, Texas, a
tributary of the Brazos River, from 2010-2012. Turtles were collected daily via
specialized traps which take advantage of repetitive basking habits, individually marked,
measured, identified, and then released from June to October 2010, April to October
2011, and April to October 2012. Multiple recaptures allowed for observation of
individual, population, and community progression over time. This manuscript asks three
fundamental questions about the role of basking behavior in the Waco Creek emydid
turtles: 1) What is the significance of the basking community assemblage composition in
Waco Creek, 2) How do basking trap modifications and population demographic
selection affect group trap response, and 3) How do polynomial and k-growth mixed
models describe juvenile turtle logistic growth?
Trachemys scripta elegans comprise 46%, Pseudemys texana 32%, and
Graptemys pseudogeographica kohnii 23% sample composition within the Waco Creek
basking turtle assemblage. All mature populations were significantly male skewed and
turtle demographics exhibited several expected seasonal behavior patterns. The
community has a large abundance of juveniles, young males, and immature females
regardless of species. In addition, juvenile T. scripta appear to be the most actively
basking demographic. Between individual demographic behavior and trap design as
predictors for trap response, demographic behavior was significant across most response
variables whereas trap design variables were not. This study pioneered a new technique
for comparing turtle logistic growth models using a polynomial mixed model as a control.
With an adequate sample size and consistent seasonal dispersal, results from this
technique agree with reports from the literature and look promising.