Literaturdatenbank
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Fendrich, R. H. , Home range, habitat use, and mortality of hatchling and juvenile ornate box turtles (terrapene ornata ornata) in iowa (abstract). Unpublished paper presented at 2013 Box Turtle Conservation Workshop.
Added by: Admin (06 Jan 2014 18:24:24 UTC) |
| Resource type: Conference Paper BibTeX citation key: anon2013.15085 View all bibliographic details  |
Categories: General Keywords: Emydidae, Habitat - habitat, Nordamerika - North America, Schildkröten - turtles + tortoises, Terrapene ornata Creators: Fendrich Collection: 2013 Box Turtle Conservation Workshop |
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| Abstract |
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The ornate box turtle, Terrapene ornata ornata, is threatened in Iowa, as the species’ prairie habitat has mostly been converted into agricultural land, reducing and fragmenting natural habitat, increasing contact with motor vehicles, farm implements, and most likely with mesopredators like raccoons, which thrive around humans and edge habitats. Our long-term project strives to understand the ecology and natural history of the second largest population of T. ornata in Iowa and provide information to management agencies to help develop conservation plans for this species. Perhaps the largest gap in our knowledge of ornate box turtles pertains to the biology of juveniles or hatchlings, as they are both uncommon and secretive. With the advent of miniature radio telemetry transmitters, we have begun monitoring hatchling and juvenile turtles to obtain data on home range, habitat, and microhabitat. I will discuss the results from our first two years of efforts at tracking hatchlings and juveniles. We tracked 19 adult turtles, 12 hatchling turtles, and 9 juvenile turtles in the Hawkeye Wildlife Area in Johnson County, Iowa, during the summers of 2011 and 2012 using radio telemetry. We recorded each turtle’s GPS coordinates daily and calculated their home ranges using 95% fixed kernels and minimum convex polygons. In addition, we gathered data on mortality, habitat, and microhabitat used by these turtles. Mean adult weekly and monthly home ranges were consistently larger than weekly and monthly juvenile and hatchling home ranges. Juvenile home ranges were not significantly different than hatchling home ranges. Habitat and microhabitat preferences varied based on age. Juveniles were far more likely than either adults or hatchlings to be found in a forest habitat, while hatchlings were more likely to be found in prairie. No age group spent more time in agricultural fields, even though the nesting area was within 100 meters of agriculture. Hatchlings were far more likely to be found buried than were juveniles or adults. While our sample remains small in both number of individuals and duration of individual observations for hatchlings, it appears that compared to older turtles, hatchlings have smaller home ranges and use fewer different habitat types. This may simply reflect reduced movement compared to older turtles. If they do not move far from the nesting site in the first month after emerging, they will encounter mostly prairie habitat. The reduced movement may reflect simple size scaling of movements or a greater need to remain underground to avoid predators or high daytime temperatures. During 2011, one hatchling died from human causes; during the summer of 2012, all seven of our hatchlings were preyed upon within two months of the time we began tracking them. While it remains unclear whether predation on nests, hatchlings and juveniles is artificially high at our site, predation on early life stages is substantial; our data suggest that the nesting site and the immediate surrounding area might be an appropriate and cost-effective focus for conservation measures.
Added by: Admin |