Survival of the western pond turtle (Emys marmorata) in an urban California environment

Publication Type:

Journal Article

Authors:

Spinks, Phillip Q.; Pauly, Gregory B.; Crayon, John J.; Shaffer, H. Bradley

Source:

Biological Conservation, Elsevier Science Ltd., Volume 113, Issue 2, p.257-267 (2003)

Call Number:

A03SPI01IDUS

URL:

http://www.nhm.org/site/sites/default/files/herpetology/pdf/SpinksEtAl2003_marms.pdf

Keywords:

Emys marmorata, Pacific Pond Turtle, Western Pond Turtle

Abstract:

The western pond turtle Emys (formerly Clemmys) marmorata is declining throughout its range, primarily due to loss of habitat from urbanization and conversion to agriculture. Urban waterways present several important challenges to freshwater turtle populations, but they also present an opportunity to maintain declining species in a ubiquitous habitat that has high public visibility. The arboretum waterway on the University of California, Davis, campus is an example of an extensively altered urban habitat that supports a relatively large E. marmorata population. Over the last 6 years, the authors monitored the turtle population inhabiting the arboretum waterway to determine the demographic health of the population and the challenges and opportunities that urban environments pose for pond turtles. Since 1993, the naturally existing arboretum pond turtle population has declined by approximately 40% and has shown little natural recruitment. During this time, the authors also introduced 31 headstarted turtles into the arboretum. (Headstarting is the process of raising juveniles in captivity until they have outgrown their period of greatest vulnerability to predators and then releasing them into the wild.) The headstarting results demonstrate that this contentious strategy is a viable option for adding young turtles to the population, but it does not address the causes of decline. Over the course of this study, nine species of nonnative turtles were encountered in the waterway, and these appear to be a serious threat to the native species. As more habitat becomes urbanized, it is increasingly important to understand how freshwater turtles, such as E. marmorata, adapt to urban waterways and what the impact of nonnative turtles is on native turtle species. The authors believe that urban waterways can provide habitat for viable populations of freshwater turtles and showcase them to the public, but both aquatic and terrestrial habitats must be managed according to the biological requirements of individual species.