Demography of the spotted turtle (clemmys guttata) in Illinois
Feng, Christina Yen
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https://hdl.handle.net/2142/101120
Description
Title
Demography of the spotted turtle (clemmys guttata) in Illinois
Author(s)
Feng, Christina Yen
Issue Date
2018-03-09
Director of Research (if dissertation) or Advisor (if thesis)
Dreslik, Michael J.
Committee Member(s)
Phillips, Christopher A.
Suski, Cory D.
Department of Study
Natural Res & Env Sci
Discipline
Natural Res & Env Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Keyword(s)
Spotted Turtle
Clemmys guttata
turtle
demography
Abstract
The Spotted Turtle (Clemmys guttata) has been well-documented and studied at two locations in Will County, Illinois, since 1987. Although spatial and reproductive ecology are relatively well understood, there remains no comprehensive demographic analysis of the two populations. I investigated the population size, structure, and demographic behavior of C. guttata populations at Lockport and Romeoville Prairie Nature Preserves by supplementing an existing dataset by conducting capture-mark-recapture in 2015–2016. I used the subsequent capture and reproductive data spanning 1988–2016 and Package RMark to analyze deterministic measures of change for both populations. Both populations exhibited an even sex ratio, a strong bias towards adults, and positive growth over the length of the study. I used a POPAN model to estimate the population size to be 116 individuals in 2010 at Romeoville and 99 individuals in 2016 at Lockport. I employed the CJSRandom model in RMark to determine age-specific survival and coupled the estimates with age-specific fecundity to create a female-only, deterministic Leslie matrix model for each population and subsequently conducted a perturbation analysis and population projection. Population growth was most sensitive to survival rates for the youngest age class and most elastic to pre-adult survival for both populations, which corroborates results on C. guttata from the species’ northern range limit and contradicts the general trend for long-lived turtle species. Neither population appears demographically viable in the long-term although their short-term dynamics appear stable.
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