In 2013 and 2014, the Zoology Program conducted amphibian surveys on Prince of Wales Island. The specific goals of the project were to (a) gather baseline data on amphibian distribution, species composition, and habitat use, with a focus on wetlands within or downstream of karst topography, (b) resurvey monitoring sites established by Pyare et al. (2004-2006) to document continued presence or absence of amphibians in non-karst habitats, and (c) compare the extent to which amphibians use karst and non-karst habitats and the suitability of site characteristics as they relate to amphibian occupancy between the two habitat types. Understanding a species’ ecological role and predicting the effect of habitat change on a species requires awareness of habitat preferences. To our knowledge, our study is the first in Southeast Alaska to investigate habitat usage of karst-influenced wetlands by amphibians.
Studies elsewhere in North America have indicated that old growth loss has had negative impacts on amphibians. Karst systems on Prince of Wales Island often support old growth and are highly productive ecosystems. Timber harvest on Prince of Wales Island has been disproportionately higher in these landscapes due to the presence of large, dense forest stands. If amphibians exhibited a preference for karst wetlands, this could have implications for forest management practices in the future.
This study occurred during the amphibian breeding season (June/July) of 2013 (Year I) and 2014 (Year II). During Year I, we revisited a subset of monitoring sites established by Pyare et al. to document occupancy rates, and conducted a pilot survey for amphibians in karst habitats (Walton et al. 2014). During Year II, we focused our surveys in both karst and non-karst sites to assess the influence of karst topography on amphibian distribution and abundance and to gain a better understanding of overall habitat preferences. During 2013 and 2014 we surveyed 220 wetlands for amphibians on Prince of Wales Island, in both karst and non-karst influenced habitats. Species composition included western toads and rough-skinned newts, which were detected in juvenile and adult life stages. Both species have been previously described on the island, with most historical observations from the central part of the island. We added 28 western toad and 56 rough-skinned newt detection sites, with an emphasis on the northwest corner of the island, increasing our overall knowledge of amphibian distribution on Prince of Wales Island.
This project was funded through the Alaska Department of Fish and Game: Threatened, Endangered, and Diversity Species Program. In addition to field crew members from Alaska Center for Conservation Science, Marian Snively and Michael Kohan of Alaska Department of Fish and Game participated in the survey efforts for 2013.