The availability of suitable basking sites is important for freshwater turtles. Basking in the sun elevates the turtle's body temperature, so permitting digestion of food. It also provides vitamin D and helps rid the body of ectoparasites. Suitable basking sites must have exposure to the sun, be accessible to turtles, and provide a safe site from predators and disturbance. Turtles are often seen basking on logs that are partially in water and partially on the shore. These slanted logs give turtles a choice to either climb completely out of the water or remain partially submerged. Other natural basking sites include rhizome mats of water lilies and exposed sites on the shoreline.
Water bodies with few natural basking sites may benefit from the addition of basking logs. Turtles readily use different types of installed logs and platforms, and the choice often depends on the availability of materials and resources.
Installation of Basking Logs
Examples of basking structures for habitat enhancement
1. Fallen logs from the vicinity of the water body or logs brought in to the site from elsewhere (suggested diameter at least 30 cm) are ideal; the larger the better); use machinery or roll the logs into water, then tow them with a boat to desired location and anchor them in place. Two logs can be tied together, side by side, to create a larger surface for turtles and to prevent them from rolling.
2. Mill-end slabs with one side milled and the other side with bark attached (3 - 4 m long; ~30 cm wide) are also suitable. These slabs are the by-product of lumber processing and can be obtained inexpensively or even for free - ask your local saw mills. The slabs are relatively light and can be carried into water by one person and then towed with a boat to desired location. However, they are not as durable as round logs and can become water-logged or sink with the weight of aquatic vegetation after only a few years.
Selecting location for basking logs
- Select a sunny area, such as the north side of the water body.
- Select a secluded site away from people, pets, and areas where trails are close to the shore; turtles are wary of disturbance from land.
- Use locations where the logs will be visible from a vantage point along the shore; this will help with monitoring of their use by turtles.
Installing basking logs
- Place the logs perpendicular to the shoreline with one end firmly attached to the shore or shoreline vegetation; in our experience, turtles are reluctant to use floating boards away from the shoreline.
- Where feasible, attempt to place the log at an angle with the shore-end raised; this provides a range of distances from the water for turtles and allows for water level fluctuations. This may not be possible at all sites, such as where there is much aquatic vegetation near the shore.
- Anchor the log firmly in place at the shore-end. For mill-end slabs, drill a hole near the end and push a 5' or longer rebar through the hole and into the shore, bottom substrate, or matted vegetation. For larger logs, use rope to secure the end to trees or shrubs (such as willows along the shoreline), or use an anchor.
Camosun Environmental Technology students Alanna Umphrey, Amanda Kletchko, Danny Desrosiers, & Marie Burgess prepared a report on basking log use at Swan Lake: "Basking Preferences and Interspecies Interactions of the Western Painted Turtle (Chrysemys picta bellii) at Swan Lake, Victoria, BC", Umphrey, Kletchko, Desrosiers, & Burgess, 2012. They designed small basking structures with floats for use in smaller ponds. While turtles readily use these structures, longer-term monitoring has revealed that they are likely to flip over in winter storms and provide only a short-term solution.
- ↑ Engelstoft, C. and K. Ovaska. 2011. Western Painted Turtle surveys and stewardship activities on Vancouver Island in 2010. Unpublished report prepared for Habitat Acquisition Trust, Victoria, BC. 67 pp.