Mark-recapture data from 7888 individuals spanning 28 years along with reproductive characteristics for 196 litters (4905 offspring) were used to analyze temporal and spatial variation in demographic parameters of the recently de-listed Lake Erie Watersnake, Nerodia sipedon insularum. Specifically, goals were to 1) determine whether demographic parameters had increased following a rapid shift in diet, 2) identify sources of temporal and spatial variation 3) provide estimates of sub-adult (neonate and juvenile) survival and 4) provide current estimates of adult survival, reproductive output and population growth that demonstrate recovery. Using data from 41 litters (844 offspring) in the pre-round goby period and 155 litters (4061 offspring) in the post-round goby period, I found that both litter size and offspring SVL have increased. Similarly, post-partum mass also increased (26% heavier). Although mark-recapture data from early in this study (1980-1983) were limited, comparisons at one site (North Bass Island) indicated survival has increased by 17% in males (from 28% in 1980-1983 to 45% in 1996-2008) and 4% in females (from 66% in 1980-1983 to 70% in 1996-2008). Analysis of recent data (1996-2008) showed that spatial variation, but not temporal variation, was an important factor in adult survival, both among islands and among sites within islands. Sex influenced survival, but without clear pattern; male survival was higher at some sites and female survival was higher at others. Age influenced survival within a single site, increasing from 18% as neonates, to 21-53% as juveniles before reaching adult levels (60-78%). These survival estimates are combined with results from the literature as a large summary table found in the supplemental materials to this dissertation. Litter size varied among years when sites were pooled, and within a single site. The proportion of gravid females varied temporally, ranging from 80-97% over 5 years. The realized population growth rate also varied temporally over 8 years (mean: 1.07, range: 0.90 to 1.21, σ2 = 0.014). The combined results of this long-term, detailed study allow for a thorough review of the demographic parameters currently controlling population growth and are important for investigating the role of large-scale processes and their influence on life-history.
Some files may require a special program or browser plug-in. More Information
|Advisor:||King, Richard B.|
|Commitee:||Gasser, Kenneth, King, Bethia, Meserve, Peter, VonEnde, Carl|
|School:||Northern Illinois University|
|School Location:||United States -- Illinois|
|Source:||DAI-B 73/11(E), Dissertation Abstracts International|
|Keywords:||Demography, Lake Erie watersnake, Mark-recapture, Reproduction, Snake, Survival|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be