| Abstract/Description or Keywords |
The objectives of this base-level amphibian assessment were to determine the distribution of amphibians within the Fish and Wildlife Compensation Program (FWCP) project area, provide a benchmark for future population monitoring, and to survey for the presence of Batrachochytrium dendrobatidis (Bd), or chytrid fungus. This survey is a continuation of 2008 surveys—2008 and 2009 surveys were intended to follow up 1995 and 2005 amphibian surveys in the East Kootenay which suggested that the Western Toad (Bufo boreas) had disappeared from several historic breeding sites. Surveys were conducted within the Interior Cedar-Hemlock (ICH) Biogeoclimatic Ecosystem Classification (BEC) zone of the Columbia Forest District, in south-eastern British Columbia. Survey protocols followed those developed in 2008 in the Arrow-Boundary and Kootenay Forest Districts. Forty-three random wetland sample sites were conducted through GIS analysis of TRIM data. Visual encounter and dipnet surveys were conducted over 17 days from 5 July – 24 July 2009. Each site was visited once. Amphibians were found at 88% of the wetlands sampled and breeding was confirmed at 63% of the sites. These proportions are less than those reported in 2008 in the Arrow-Boundary and Kootenay Forest Districts. The Columbia Spotted Frog (Rana luteiventris) was found at most sites (74%) followed by the Long-toed Salamander (Ambystoma macrodactylum) (28% of sites), Western Toad (28% of sites), and the Pacific Chorus Frog (Pseudacris regilla) (5% of sites). Breeding-site encounter rate for the Western Toad was 0.28 compared to 0.23 for the Arrow-Boundary and Kootenay Forest Districts, 0.04 in Southeast Alaska and 0.19 in the East Kootenay. The Columbia Forest District is likely an important breeding region for the species. Amphibian species richness was lower than that in the Arrow-Boundary and Kootenay Forest Districts but higher than that reported in the East Kootenays. Twenty-one sites (48.8%) had one species present, 14 sites (32.6%) had two species, three sites (7.0%) had three species and no sites had more than three species present. There was no relationship between amphibian species richness and known fish presence. American beaver (Castor canadensis) activity was noted at most sites (67.4%, n = 29). The prevalence of Bd in sampled adult amphibians in the Columbia Forest District was alarmingly high (69%). Forty R. luteiventris (71%) and five (56%) B. boreas samples tested positive for Bd. This contrasts to tests from the Arrow-Boundary and Kootenay Forest Districts in 2008 when only three of 46 samples (7%) tested positive for Bd. Occurrence within wetlands (93%) was much higher than reported elsewhere. These results confirm the presence of Bd in additional B. boreas populations in Canada. We recommend close monitoring to document the extent and distribution of this fungus within the region and between species. Most (95%) of the sampled wetlands were classified as small (<10 ha). In our opinion, randomly selecting wetlands sample sites through GIS using TRIM data is an effective way to satisfy the requirements of occupancy modeling and these sites are good candidates for future amphibian monitoring using proportion of area occupied (PAO) analysis. In order to determine occupancy rates for each amphibian species, we recommend sampling each site at least twice over the breeding season, preferably with two observers collecting data independently. The completion of this base-level amphibian assessment is a first step toward mid-level amphibian monitoring and we recommend continuing and expanding base-level amphibian monitoring throughout the FWCP project area. If long term monitoring reveals that regional amphibian species are in decline, apex-level monitoring efforts may help determine the causes. Habitat management could include actions such as stewardship outreach, land use planning, land acquisitions, protection of breeding areas and connectivity corridors, mitigating for road mortality and habitat enhancement or restoration. Non-habitat management tools might include captive breeding, population augmentation and translocations, non-native species control and predator or competitor control. These actions would require follow-up monitoring to ensure their efficacy. |
