Abstract/Details

Spatial ecology, population structure, and conservation of the wood turtle, Glyptemys insculpta, in central New England


2009 2009

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Abstract (summary)

Wood turtles (Glyptemys insculpta) are of conservation interest rangewide. Anecdotal accounts demonstrate that some populations have been decimated since 1850, and recent studies demonstrate that declines are still underway. From 2004–2008 I investigated the ecology of wood turtles in Massachusetts and New Hampshire. I obtained between one and five years of annual home range data for 150 turtles, and evaluated population structure at 31 sites in five major watersheds.

Seasonal floods displaced 7% of wood turtles annually in one watershed, and accounted for elevated mortality. Twelve wood turtles were displaced < 16.8 km, and two were displaced over a 65-foot dam. Several turtles overwintered at their displacement site and two returned successfully, indicating that floods are a mechanism of population connectivity. Several homing turtles ended up in new areas. Turtles occupied stream segments with gradient < 1%, lower than generally available. </p>

Agricultural machinery accounted for most observed mortality, followed by automobiles and mammals. Female turtles exhibit smaller home ranges in agricultural areas. Older turtles move farther from the river than do young turtles, possibly reflecting their familiarity with a former landscape.

Population density ranged from 0–40.4 turtles/river-kilometer. The highest densities occur in central New Hampshire and lower densities occur in the Housatonic watershed. Population density is negatively correlated with agriculture at both riparian and watershed scales, and responds unimodally to forest cover. Wood turtle populations in western Massachusetts are declining by 6.6–11.2% annually.

I estimated ages of turtles by assessing shell-wear rates from photographs. Wood turtles regularly achieve ages over 80 years, and like related species, do not exhibit clear signs of senescence. Old wood turtles are reproductively dominant, and their survival rates are twice as high as young turtles. Carapace scutes appear to require 80 years to become worn.

Population modeling indicates that wood turtle populations are declining in New England due to anthropogenic and natural factors. Conservation efforts must address the effects of agriculture on adult survival. Climate change may negatively affect northeastern wood turtles through increased flooding. Populations in mountainous areas may be likely candidates for conservation because they don't occupy prime agricultural land, but may be more susceptible to floods.

Indexing (details)


Subject
Ecology;
Organismal biology;
Forestry
Classification
0329: Ecology
0472: Organismal biology
0478: Forestry
Identifier / keyword
Biological sciences, Conservation, Emydidae, Glyptemys insculpta, Home range, Senescence, Wood turtles
Title
Spatial ecology, population structure, and conservation of the wood turtle, Glyptemys insculpta, in central New England
Author
Jones, Michael T.
Number of pages
265
Publication year
2009
Degree date
2009
School code
0118
Source
DAI-B 70/06, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9781109190076
Advisor
Sievert, Paul R.
Committee member
Fuller, Todd K.; Melvin, Scott M.; Richmond, Alan M.
University/institution
University of Massachusetts Amherst
Department
Organismic & Evolutionary Biology
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3359143
ProQuest document ID
304921373
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304921373
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