Western Pond Turtle Summer Habitat Use in a Coastal Watershed

Western pond turtle (Actinemys marmorata) habitat use was studied in a coastal pond, lagoon, and stream system during the summer of 1995 and 1996 at Waddell Creek, Santa Cruz County, California. Location and habitat association data were recorded for locations and sightings of radio-tagged and un-tagged turtles during the normal active season. Summary comparison of habitat associations and habitat availability provided inference of habitat preference at several habitat scales. For most of the active season the turtles were in relatively sunny aquatic habitat, in deeper, slower velocity water. In addition, the turtles were most commonly associated with exposed and sub-surface woody debris, rooted bank, and branches positioned near the water surface. In the lagoon and stream this was usually associated with the thalweg and along positions just off the bank, where large wood and pool scour was most abundant. Newly placed and relocated floating wood was utilized for basking within days by radio-tagged and untagged turtles. Subsequent data on the basking behavior of a sub-set of radio-tagged turtles was developed with externally attached temperature sensors to chronicle periods when the turtle shell was exposed to sun. A regular pattern of extensive daily basking was identified in all thermistor-fitted turtles. The combination of sunny aquatic habitat with natural structural elements, particularly woody debris, which provided escape cover and basking opportunities, appeared to be the preferred habitat for this species