Searching for Wex̱és (frogs) on Cha7élkwnech/Gambier Island

Summary

Identification of the distribution of species at-risk is a key step in ensuring the protection of that species. Presence and distribution data indicates habitat that needs protecting as well as directs monitoring efforts for populations. We are continuing our mission to strengthen collaboration in Átl'ḵa7tsem / Howe Sound and are collaborating with the Islands Trust Conservancy, the Gambier Island Conservancy and the Sḵwx̱wú7mesh Úxwumixw to fund a scientific research project to sample creeks for eDNA within seven watersheds on Gambier Island to determine the presence of the Coastal Tailed Frog. Once presence is known, this study will continue to assess the abundance of this species within the watersheds, as well as the productivity of the habitats they inhabit.

View Project Updates

The Need

Gambier is the largest island in Howe Sound, spanning roughly 69 square kilometres of a highly complex landscape. At least ten watersheds lead to the ocean in all directions. Riparian areas and wetlands support at least five amphibian species and have probably remained isolated from the mainland for about 10,000 years (i). These freshwater ecosystems are home to a massive diversity of species which provide extensive ecosystem services (ii).

Remarkably, Gambier Island retains a large interconnected mosaic of highly productive, old and mature forest, an ecological asset increasingly rare in south coastal BC. Sustaining contiguous habitat complexity is essential for ecosystem resilience that sustains a rich diversity of old forest-dependent species (iii). Large contiguous areas of complex old forest are increasingly rare on the Southern Gulf Islands and threats from habitat loss and fragmentation have already caused extinctions of unique and irreplaceable components of biodiversity in these geographically isolated landscapes (iv). Because of the rarity of this type of ecosystem in the region, Gambier Island is home to many species at risk of extinction (v). Most of these species are threatened by disturbances due to the extent of human settlements and the rapid rate of forest harvesting in south coastal BC.

Amphibian species' existence is threatened due to human activities in these freshwater systems, as streams are critical to amphibian survival for at least one life stage. Amphibians are extremely vulnerable to disruption, with population declines happening more rapidly than for birds or mammals; an estimated 70% of amphibian species are experiencing population declines (vi). At-risk amphibians reported to have been found on the island include the Coastal Tailed Frog and the Red-Legged Frog.

The Coastal Tailed Frog has been observed in streams on Gambier (vii). The Coastal Tailed Frog and Northern Red-Legged Frog are listed as a Special Concern by SARA, but no records exist in the BC Government Conservation Data center (2020). Coastal Tailed Frogs are rare on islands (viii) and the geographically isolated Gambier Island population is probably unique from surrounding mainland populations. We risk losing a significant component of biological diversity before it is formally recognized.

Project Objectives

Phase 1:

Conduct eDNA sampling in seven of Gambier Island’s Watersheds
Analyze samples and produce data used for determining the distribution of Coastal Tailed F-frog on Gambier Island
The results will be summarized in a report that will also inform on the impacts of logging to prime habitat for these frogs

Phase 2:

Determine tadpole abundance and productivity of natal areas among streams where Coastal Tailed Frog presence has already been detected from Phase 1
Develop a rigorous sampling plan with sufficient statistical power to monitor productivity among natal areas
Select sentinel sites for long term monitoring and inform conservation status with trends in abundance

Project Benefits

The results of this project will provide a better understanding of the presence and distribution of the Coastal Tailed Frog on Gambier Island through the analysis of eDNA testing. This knowledge will help inform the Islands Trust Conservancy and Howe Sound Biosphere Region Initiatives Society’s conservation planning and can also inform forestry operations on potential areas where damage to critical Coastal Tailed Frog habitat has occurred or could occur in the future.

This research is beginning to inform the conservation status for CTF and has the potential to expand the known species range in BC.

Location

Gambier Island.

What Was Found?

Results from phase 1 indicate that coastal tailed frogs are present in at least 5 streams within the study area
During sampling of one of the stream systems, a CTF tadpole was identified!

Project Updates

April 2024

After successfully applying for a provincial sampling permit, sampling for Coastal Tailed Frogs continued on Gambier Island. The field personnel visited 19 sites and employed a 15-minute time constrained survey to determine the abundance of this species among the five streams identified in Phase 1. A total of 26 tadpoles, one juvenile and one adult were found in four of the five streams. Presence of natal areas (where tadpoles can be found) were identified among three streams, but were not found in Andy’s Bay Creek.

A grant application to fund more sampling in 2024 was submitted to the Habitat Conservation Trust Foundation by Stamford Environmental in November of 2023. Unfortunately, this application for the 2024 funding round was unsuccessful.

August 2023

Beginning phase 2

HSBRIS in partnership with the Gambier Island Conservancy has contracted Stamford Environmental again to continue this project. A sampling methodology is currently being developed to assess the abundance of this species as well as the productivity of natal areas in stream systems where results from phase 1 indicated Coastal Tailed Frog presence. A permit application to survey for this species has been submitted to the Ministry of Waters Lands and Resource Stewardship.

April 2023

Phase 1 is now complete!

During summer 2022, sampling of all seven major watersheds took place on Gambier Island with 34 sample sites and 37 samples collected. A full report of the field operation was provided at the end of November, and samples collected during the summer were sent for analysis to UNBC in early 2023.

Deliverables & Resources

Deliverables:

Progress Report - Coastal Tailed Frogs Environmental eDNA Project Gambier

Searching for Wex̱és (frogs) on Cha7élkwnech/Gambier Island – Field Summary Report 2023

Resources & Other Materials:

COSEWIC Assessment and Status Report on the Coastal Tailed Frog

i - Friele & Clague, 2002, ii - Meidinger & Pojar, 1991, iii - e.g. Doyle and Yadao 1999; Gayton and Almuedo 2012; Oliver et al. 2015. iv - Harding and McCallum 1994; Cannings and Cannings 1996, v - BC Conservation Data Center, 2020, vi - Abney et al., 2019, vii - e.g. Doyle and Yadao 1999, viii - Environment and Climate Change 2016