[PDF] Population Structure Life History And Terrestrial Movements Of Western Pond Turtles Actinemys Marmorata In Lentic Habitats Along The Trinity River California eBook

Author : Barry S. Nerhus (Jr.)
Publisher :
Page : 60 pages
File Size : 33,19 MB
Release : 2016
Category : Pond animals
ISBN : 9781339687421

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Abstract: This study investigates the population dynamics, movements, and habitat use of a population of western pond turtles in Orange County, California from 2008-2012 using radio telemetry and mark-recapture data. Western pond turtles have been thought to be declining throughout their range. However, few studies have documented their status in southern California, where urbanization has changed the landscape drastically in recent decades. I individually marked 236 pond turtles using hoop-net funnel traps and estimated the population size at 308 individuals, which is the largest estimate reported in southern California. Mean capture per unit effort was 5.03±0.87. Mean female carapace length (CL) (142±14mm) was not significantly larger than males (139±14 mm). I also documented 20 nest and 9 estivation locations. Mean distances included 176 ±130.80 meters (m) and 91±58.6 m. These data identify the population demography, which can be a metric of population stability. Other known populations need to be estimated to determine their regional status.

Author : Cristina Yarnal
Publisher :
Page : pages
File Size : 44,40 MB
Release : 2019
Category :
ISBN :

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This project provides insight into western pond turtle (Actinemys marmorata) population health at sites in three states on the western part of the United States. Washington, Oregon and California have identified the western pond turtle as endangered, a critical and a species of special concern in that respective order. Washington has implemented a recovery plan for western pond turtles and Oregon has established best management practices for the conservation of native turtles. California has yet to establish any guidelines for the conservation of western pond turtles. This species is endemic to the western United States and has been suffering from declining populations since the late 1800s. The factors that have contributed to the decline in western pond turtle numbers include: historical commercial food use, habitat destruction and fragmentation by water diversions, urbanization and agriculture, non-native species interactions, fire, drought, and flood which are increased by climate change due to anthropogenic activity. Reptiles in general do not do well with high disturbance rates in their environment, due to their slow movements. Western pond turtles have also been afflicted by different diseases, such as a respiratory illness that decimated one-third of the population in Washington and shell disease that has been affecting populations in Washington, Oregon and California. Exposure to diseases is proliferated by contact with released pet turtles, as captive turtles contain different bacteria. The western pond turtle sites analyzed are in the Columbia Gorge and South Puget Sound in Washington, Willamette Drainage in Oregon and sites in Lake County, San Diego County and Yolo County in California. These sites were analyzed through a combination of data from peer-reviewed, unpublished literature and government agency reports. The purpose of this research is to determine the effectiveness of management plans and strategies used for the recovery and conservation of western pond turtle populations, with an emphasis on head-starting programs, non-native species removal, habitat restoration and enhancement. The results will be analyzed by looking at historical data and more recent results in relatively the same area to determine if the western pond turtle populations have increased or decreased at those sites, in order to best allocate resources and prepare management plans for the conservation of western pond turtle populations in California. The recommendations being propose are surveying and monitoring, collaboration, habitat restoration/enhancement, non-native species removal, head-start programs and land acquisition. The analysis between sites in Washington, Oregon and California showed some progress but requires further research.

Author : Bethany Brock
Publisher :
Page : 262 pages
File Size : 42,36 MB
Release : 2009
Category : Western pond turtle
ISBN :

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The Pacific Pond Turtle (PPT), Actinemys (Clemmys) marmorata, is a small, highly aquatic turtle whose populations along its entire distribution range are in decline. As most of the published papers focus on the populations in the central and northern portions of the distribution range, the southern California PPT populations' demographics and overwintering ecology are not well-known or understood. A protected population of PTTs in Riverside County, California, was studied and the demographics of population size, survivorship and recapture probabilities, population structure, growth and sexual size dimorphism were analyzed. The overwintering ecology, including overwintering behaviors, timing and microhabitat characteristics of overwintering sites, of the same population were also studied using radiotelemetry. It was found that the southern California PPT population in 2008 contained approximately 120 individuals, had high adult female and juvenile survivorship rates, and lower than expected adult male survivorship rates. The population structure appeared to be that of a healthy, undisturbed population. The adult females were found to be significantly larger than the males. The PPTs exhibited terrestrial overwintering behavior as the seven turtles in the study all left the water to overwinter in upland locations. They utilized fewer locations than PPTs in northern populations and returned to the water earlier than northern PPTs. None of the study turtles were observed thermoregulating, as has been observed for all other PPT studies. The overwintering sites were located in a variety of habitat types. The knowledge gained from this study will help resource managers understand the population demographics and overwintering ecology of a robust southern California PPT population and utilize the knowledge to protect other PPT populations. Keywords: population size and structure, survivorship, sexual size dimorphism, overwintering, turtle, Pacific Pond Turtle

Author : Joseph Paul Belli
Publisher :
Page : 97 pages
File Size : 29,35 MB
Release : 2015
Category : Animal populations
ISBN :

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"Western Pond Turtles, Emys (Actinemys) marmorata, were captured (n=173) in 2011 (wet year) and 2012-2013 (successively drier drought years) along upper Coyote Creek, an intermittent stream in central California. Males outnumbered females 2.8:1, juveniles less than 120 mm long made up 26% of captures, growth rates varied among individuals, and little growth occurred in turtles older than 10 years. I radio-tracked turtles from May 2011 through August 2013 to ascertain movements and seasonal habitat use. Males had much larger home ranges than females (means of 2281 m for males and 501 m for females in 2012), and males moved extensively in April and May, during the apparent breeding season. Turtles preferred deep and complex pools, complex runs, and backwaters. Turtles left the stream for upland habitats in late spring and summer as stream flow ceased and pool connectivity was broken. There was substantial variation in departure dates among individuals and between wetter and drier reaches. Mean departure date was 16 August in 2011, but decreased to 20 July in 2012 and 28 June in 2013, as the drought intensified. Upland sites were mostly within 100 m of the stream, beneath dried leaves and/or thatch, and on slopes varying from flat to over 40%. Turtles remained upland for almost seven months in 2011-2012, although there was much variation. Mean return to stream dates were 27 February (males) and 16 March (females)." -- Author's abstract.