[PDF] An Examination Of Limiting Factors Of Chrysemys Picta Bellii Western Painted Turtles In The Lower Willamette River Basin Oregon eBook

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Page : 54 pages
File Size : 12,29 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 : Kelsey Allison Marchand
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Page : 0 pages
File Size : 46,95 MB
Release : 2017
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Understanding resource use is necessary to properly manage and conserve habitats for long-lived species, especially for populations residing urban settings. I studied habitat selection, space use, and isotopic resource use of an urban population of western painted turtles (Chrysemys picta bellii) residing in Wascana Creek in Regina, Saskatchewan from May 2015 to April 2017. Using radio-telemetry to track movements, I determined habitat selection at multiple spatial (Johnson's second and third order habitat selection) and temporal scales (active season; encompassing emergence, nesting, and post-nesting) using compositional analysis. I found that turtles selected for shoreline habitat over urban/parkland and open water (second order). The characteristics of the selected shoreline (third order) varied between habitat areas; however, they did not substantially differ across the active season. Within creek habitat, turtles chose shoreline habitat randomly. Within marsh habitat, turtles selected for particular shoreline features, preferring treed shoreline across all three periods of the active season. Across the active season, both male and female turtles moved significantly more during emergence than during nesting and post-nesting periods and movements were larger in marsh habitat than creek habitat. Suitable overwintering locations were limited within the study area, and were warmer and deeper than those randomly available, likely ensuring that their overwintering locations did not freeze. There was no significant difference in the dissolved oxygen level between used and available overwintering sites. I measured stable isotopes of carbon and nitrogen from nail samples to examine isotopic resource use within and among the populations in two habitats (marsh and creek). Isotopic niche size varied across the population as a result of variation in body size, sex, and location. Isotopic niches overlapped between 26-77%, with the least overlap between males and females. This indicates that although western painted turtles are generalist omnivores, there is indication of distinct isotopic resource use by subgroups. By comparing the isotopic values found in the turtles to those found in prey, I found that all turtles consumed low proportions of a wide variety of potential prey items, but there were differences among subgroups. Female and sub-adult turtles in the marsh consumed a higher proportion of crayfish and males consume a higher proportion of amphipods, whereas turtles in the creek consumed a higher proportion of chironomid larvae in comparison to the other available prey items. Turtles in this urban environment require aquatic systems with high productivity and diversity, vegetated shorelines to provide buffers from disturbance as well as provide suitable basking areas (i.e. banks with overhanging trees), and protected overwintering habitat that is at least 2 m deep. My findings indicate that turtles take advantage of a wide range of resources; however, there are particular requirements that are necessary to ensure their survival and long-term persistence in this environment.

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Page : 0 pages
File Size : 39,64 MB
Release : 2023
Category : Floodplain management
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This management plan has been prepared for the Lower Columbia Estuary Partnership and is intended to provide guidance for the improvement and protection of western painted turtle (Chrysemys picta bellii) habitat at the Sandy River Delta in Troutdale, Oregon. The Sandy River Delta is a 1500-acre natural area situated where the Columbia and Sandy Rivers meet. Its dynamic floodplain habitat supports a diverse assemblage of species, including the western painted turtle, an Oregon Conservation Strategy Species. A small, unknown number of western painted turtles utilize the wetland habitats of the Sandy River Delta, and the frequency in observations of these turtles has decreased over time. The habitat utilization of western painted turtles at the Sandy River Delta has likely been influenced by changes in site hydrology, disturbance by off-leash dogs, and the presence of invasive vegetation in key turtle habitat. To create this management plan, western painted turtle habitat at the Sandy River Delta was evaluated to determine the necessary management actions for habitat improvement and protection.

Author : Amy Diane Duncan
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Page : pages
File Size : 13,86 MB
Release : 2016
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Overwintering is a critical life-history stage for species inhabiting temperate environments characterized by harsh, cold winters lasting up to half the year or longer. Ectotherms, such as herpetofauna, display behavioural adaptations in order to survive winters. During this period of their life history, those animals occupying fluctuating environments, such as reservoirs, may face additional challenges. I studied the overwinter ecology of a population of Western Painted Turtles (Chrysemys picta bellii) in a hydroelectric reservoir in British Columbia, Canada. My study built upon a preliminary study on the general ecology and population demographics of this population. This preliminary study identified variation in overwintering tactics between two water bodies within the reservoir - congregated and dispersive hibernation. The specific goals of my research were to (1) document more closely the variation in overwintering tactics occurring across the different subpopulations, (2) determine if the turtles in the subpopulations were experiencing and/or selecting different conditions during hibernation, and (3) determine if changes in reservoir levels during winter elicited response(s) in the turtles, and if so, examine how this relationship contributed to the use of different tactics. I focused on two locations within the reservoir that supported the overwhelming majority of turtles, and also included a small, isolated pond not influenced by the reservoir. By using radio telemetry to track turtles over two winters, my research identified variation in the overwintering tactics used between water bodies and years, and determined that overwintering tactics did not vary with water depth, temperature or dissolved oxygen. Turtles in all locations buried in the reservoir substrate for winter. Turtles displayed longer movements in winter than those documented in similar studies; however, these movements could not be correlated to changes in water levels. Body condition was comparable between the reservoir and reference water bodies yet population density and turtle size were notably higher in the non-reservoir location. In conclusion, this population of turtles exhibited behavioural plasticity in their overwintering tactics, and did not appear to be impacted by water level fluctuations in winter.

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Page : 98 pages
File Size : 22,74 MB
Release : 2016
Category : Western painted turtle
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Western painted turtles (Chrysemys picta belli) are found occupying Fairview Creek Headwaters (FCH) in Gresham, Oregon. This urban stream contains a large wetland with an adjacent butte, all managed by the City of Gresham. This management plan addresses the preferred habitat and population of turtles at the site. A habitat delineation of the site revealed specific locations where habitat improvements could take place as well as areas of already beneficial habitat. Two site plans were prepared showing areas of the site that could be enhanced with nesting habitat as well as additional aquatic habitat and basking habitat. A habitat study was conducted comparing the terrestrial and aquatic habitat in the northern part of the site and the southern portion of the site. The northern portion of the site, where the most turtles are seen, was found to have more bare ground, with a rush species and emergent vegetation as indicator species. The southern portion of the wetland was dominated by reed canary grass and birdsfoot trefoil. This area had high plant density with very little bare ground. The aquatic habitat in the southern portion of the wetland had less emergent vegetation and more floating vegetation. Two management plans were created for Fairview Creek Headwaters northern section of the site. The first plan is a low impact plan, focusing on nesting habitat creation along the west edge of the north wetland. Plan 2 is a more comprehensive plan which includes improving aquatic habitat and basking habitat. Seven years of mark-recapture data collected on the turtle was used to summarize findings on the turtle population. Two methods were used to estimate the population size, Lincoln Petersen and Schnabel methods.