Chapter 3 – Tailed Frog as a Model for Understanding Connectivity within Aquatic, Riparian and Terrestrial Ecosystems Protocol

Principal Investigators: Chris Johnson, Brent Murray


The Tailed Frog Protocol tested a range of techniques for monitoring changes in the distribution and abundance of the coastal tailed frog (Ascaphus truei) in order to recommend methods for assessing presence and for maintaining connectivity of montane ecosystems. The coastal tailed frog is distributed from northwestern California to the Nass River north of Prince Rupert, BC (Dupuis et al. 2000). Relatively little is known of the ecology and biogeography of the species at the northern extent of their range, in the vicinity of the Pacific Trail Pipeline project. Current research, in combination with past studies from southern BC, however, indicate that post-metamorphic tailed frogs use old forest types with a particular affinity to coarse woody debris and associated subterranean structures. Larval frogs and breeding adults are dependent on cool, fast-flowing headwater streams (Dupuis et al. 2000, Matsuda and Richardson 2005, McEwan 2014). Populations of tailed frogs are negatively affected by disturbances that reduce forest and riparian structure and alter stream hydrology (Dupuis and Steventon 1999). In northwestern BC, such effects are related to forest harvesting, hydroelectric developments, and other land developments. Given their biology, limited abundance, and the threats from landscape change, the coastal tailed frog is protected under the federal Species at Risk Act (Special Concern) and provincially recognized as a Species at Risk under the BC Forest and Range Practices Act. The high sensitivity of tailed frogs to environmental change and their need for a range of aquatic and terrestrial communities suggest that they are a good species for assessing the connectivity of habitats found in wet montane ecosystems that border fast-flowing streams.

The Tailed Frog Protocol included two integrated components designed to monitor and understand changes in the connectivity of aquatic and terrestrial ecosystems by using tailed frog populations as a (qualitative and quantitative) measuring tool. The first component tested mitigation strategies using three pre-existing Experimental Watersheds near Terrace, BC (Todd et al. 2012) in close proximity to the pipeline RoW. These watersheds are representative of habitat conditions found on the RoW. At the Experimental Watersheds, we used systematic pitfall traps and radio-telemetry to reveal multi-scale resource selection and movements of individual frogs in areas that are disturbed by forest harvesting. This component of the study was partially supported by PTP and was reported in McEwan (2014). In the second component, we tested a number of direct (i.e., pitfall sampling and visual encounter surveys) and indirect (i.e., environmental DNA) techniques for measuring and monitoring the distribution and abundance of post-metamorphic tailed frog populations. Also, we conducted two studies to assess the connectivity of tailed frog populations along the pipeline RoW. This included analyses of the genetic structure and by inference the connectivity of populations from across northwest BC. Second, we studied the environmental parameters that influence the relative abundance of tadpoles in larval streams that may be bisected by the RoW. In combination, these studies investigated the movements and distribution of tailed frogs at both the ecological and evolutionary spatio-temporal scales. When complete, the data will allow for the interpretation of patterns of tailed frog distribution and can be used to guide restoration after pipeline construction.