[PDF] Nesting Activity Of The Painted Turtle Chrysemeys Picta On Beaver Island Michigan And Mechanisms Used By Predators To Locate Nesting Sites eBook

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Page : 54 pages
File Size : 44,56 MB
Release : 2021
Category : Nest building
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Oregon's two native freshwater turtle species, Chrysemys picta bellii (Western painted turtle) and Actinemys marmorata (Northwestern pond turtle), have seen significantly reduced population sizes since the founding of Portland in 1845, with estimates of up to 90% for A. marmorata. This project examined turtle nesting activity at 25 sites across a range of turtle populations and habitats around the Lower Willamette River Basin. All discovered turtle nesting activity was found in areas of high solar exposure. We found 93% of over 400 nest attempts to have been depredated across the 25 sites, well above most other reported rates. At several sites, many aborted nest attempts were found atop gravel roadbeds, indicating that lack of appropriate substrate is potentially limiting nesting success. The presence of greater than five pedestrians per hour at turtle nesting areas was correlated with a substantial decrease in nesting attempts suggesting that management of recreational activities may play a role in the amount of nesting activity occurring. Hence, site-specific solutions, such as importing substrate, alteration of path locations or seasonal trail closures to lessen human foot traffic disturbance of turtle nesting attempts, are likely to improve recruitment rates of native turtles in the Lower Willamette Basin. Further studies that improve knowledge of population demographics, the impact of human activities on turtles, and habitat needs of juvenile turtles are needed to support long-term self-sustaining turtle populations.

Author : Steven Kell
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Page : pages
File Size : 10,74 MB
Release : 2018
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Nesting is a costly time for female turtles, both energetically and from threat of predation. Females must ensure maximum survival of offspring for population stability and individual fitness. I observed signs of communal nesting in female Painted Turtles (Chrysemys picta). My goals were to determine; are females choosing to nest at high nest-densities, what cues do they use to select nest sites, are offspring benefitted. Using ArcGIS, I found that females nested in clusters, the location of clusters varied among years, and that nest site selection was not strongly determined by environmental characteristics. When female turtle models were placed on the nesting embankment females nested most often with the highest density of models. In ~25% of cases, nests were so clustered that eggs were deposited directly into existing nests or directly beside existing nests. Survival of clustered nests (49%) was higher than that of solitary nests (39%). In incubators, older clutches had faster incubation times, suggesting embryonic communication as a mechanism promoting hatching synchrony. We strongly suggest that female Painted Turtles choose to nest in close proximity to conspecifics, and that this clustering results in a fitness benefit.

Author : Jenny Lynn Rutherford
Publisher :
Page : 54 pages
File Size : 17,9 MB
Release : 2010
Category : Turtles
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Understanding predator foraging habits and nesting ecology of turtles is essential for the long term management of predator and prey. The objectives of this study were to (1) collect descriptive data on nesting ecology, including nest predation rate of a Wood Turtle population in the Upper Peninsula of Michigan, (2) investigate potential cues used by predators for location of Wood Turtle nests, and (3) determine effects of the distance of nests from a river on predation. Natural nests (identified by oviposition behavior of females) were marked and monitored for predation. Additionally, simulated nests were created with 1 of 4 treatments applied: soil disturbance, turtle-scented water, soil disturbance and turtle-scented water, and distilled water (control). In a second experiment, artificial nests with buried chicken eggs were created at varying distances from the river and monitored for predation. Natural nest in this study experienced a low predation rate (4/7) compared to other studies. This result may be an artifact of small sample size or the remoteness of the study area, absence of human disturbance and resulting low density of raccoons. My results also suggest that nest predators used soil disturbance cues primarily for locating nests. Thus, applying a chemical cue to artificial nests in future empirical nest predation studies may be irrelevant. Nest predation decreased as nest distance from the river increased, which may have important conservation implications for future management plans.