Publication Date

Fall 2015

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Advisor

Jerry J. Smith

Subject Areas

Conservation biology

Abstract

By Joseph P. Belli

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).

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