San Juan Island National Historical Park amphibian inventory 2002

Samora, Barbara; Layes, Michael; Lofgren, Rebecca

This document details amphibian inventories conducted at San Juan National Historical Park (SAJH) as part of a larger effort to document species presence at five North Coast and Cascades Network (NCCN) parks: Mount Rainier National Park (MORA), Ebey’s Landing National Historical Reserve (EBLA), Lewis and Clark National Historical Site (LEWI), Fort Vancouver National Historic Site (FOVA), and San Juan Island National Historical Park (SAJH). Four parks (EBLA, FOCL, FOVA, and SAJH) had incomplete amphibian lists based on limited or undocumented data. Our primary goal was to meet the National Park Service Inventory and Monitoring program goal to better assess the status of amphibian species listed as “expected” in the parks and to verify the occurrence of 90% of these species. Species occurrences were documented or verified by written records and photographs; no specimens were collected in this inventory. Prior to this inventory, SAJH had no verified list of amphibians or reptiles occurring in the park, however a wetland study conducted by Holmes (1998) documented incidental observations of two frog species. Additional searches of museum specimens and state records have not been completed. Our primary goal for SAJH was to search for the presence of expected species: Ensatina (Ensatina eschscholtzii), western red-backed salamander (Plethodon vehiculum), northern red-legged frog (Rana aurora), Oregon spotted frog (Rana pretiosa), American bullfrog (Lithobates catesbeianus), Pacific treefrog (Pseudacris regilla), and western toad (Anaxyrus boreas). Inventories of reptiles were not targeted during this project; however they were documented when encountered and are reported in this document. This report provides an updated list of amphibian species present within SAJH, describes the methods used for and results of the surveys, and discusses each species detected. The results include a summary of species documented at each survey site, information on species life stage and habitat, and maps showing the spatial distributions of amphibians in the park. The appendices include more details on information documented in the inventory. One voucher photograph was taken for the northern red-legged frog observation. Voucher specimens for amphibians and reptiles exist for many NCCN species in various park collections and at other institutions. These collections, along with new data provided through this inventory, represent an historic amphibian collection for additional research in the future. Fourteen surveys were conducted at American Camp and 15 surveys at English Camp. We confirmed the presence of two species in SAJH in this inventory: northern red-legged frog and Pacific treefrog. Amphibian habitat is sparse on San Juan Island and within SAJH, one of the driest parks in the NCCN, with only one permanent pond located at American Camp and no perennial streams. Several surveys of palustrine wetlands did not result in amphibian detections. This inventory was conducted during April 2002 and when surveys were initiated, many areas were already too dry to support amphibians. A follow up survey in late February and early March could possibly yield additional amphibian species detections. Species absence is extremely difficult to determine and it is possible that some species recorded historically or occasionally but not detected during our survey efforts may still be present in the park. Additional surveys of targeted habitats and species should be conducted.

San Juan Island National Historical Park amphibian inventory 2002

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