A Survey of Small Mammals in Wood-Tikchik State Park, Alaska

Abstract

Wood-Tikchik State Park in southwestern Alaska is the largest state park in the United States (7000 km2), however relatively little is known about the small mammal communities occurring in the area. Wood-Tikchik State Park is located approximately 30 km north of Dillingham in southwestern Alaska. Glaciation was the main influence in creating the Park's many features which include spire shaped granite peaks, rising from near sea level to 1525 m. From 1936 to 1938, Olaus Murie conducted a faunal survey of the Alaska Peninsula and Aleutian Islands. He reported that the masked shrew (Sorex cinereus), dusky shrew (S. monticolus), short-tailed weasel (Mustela erminea), and meadow jumping mouse (Zapus hudsonius) had been collected from the Dillingham area in the early 1900s, but apparently did no collecting himself in this area (Murie 1959. North American Fauna 61:1-406.). In 1972, Grumman Ecosystems Corporation conducted an inventory of the Park's resources, including incidental observations of small mammals (unpublished report on file at Alaska Department of Natural Resources, State Parks, Anchorage, AK 99503). Forty-two trap nights yielded only single specimens of the northern red-backed vole (Clethrionomys rutilus), deer mouse (Peromyscus maniculatus), tundra vole (Microtus oeconomus), Z. hudsonius and collared lemming Dicrostonyx groerlland icus). The methods used, including trap locations, trap types, habitats surveyed, and procedures for identifying specimens were not documented in the Grumman report. The meadow vole (M. pennsylvanicus) is also thought to occur in the Park, but no positive verification is available (P. Caswell, U.S. Fish and Wildlife Service; pers. comm.). To provide a current and more reliable inventory of small mammal species occurring in the Park we systematically trapped available habitats at 2 localities from June to September 1994. Our primary trapping site was along the Agulukpak River, which drains Lake Beverly into Lake Nerka in the Wood River Lakes. Mixed forest, meadow, wet tundra, and meadow/mixed forest edge are the dominant habitats near the river. Mixed forest consists of white spruce (Picea glauca), birch (Betula spp.), balsam poplar (Populus balsamifera), ferns (Athyrium, Mattiuccia, and Dryopteris spp.), and grasses (Poa spp.). Meadow habitat consists predominantly of grasses and fireweed (Epilobium angustifolium); whereas sedges (Carex spp.), cottongrass (Eriophorum spp.), crowberry (Empetrum nigrum), and sphagnum moss (Sphagnum spp.) predominate in the wet tundra habitat. The other location was Eagle Island, a 43.7-ha island in Lake Tikchik composed mainly of mixed forest, dry tundra and shrub edge habitats. Dry tundra is composed predominantly of E. nigrum, dwarf blueberry (Vaccinium caespitosum), and lichens (Cladina rangiferina and Cetraria islandica). Shrubs include dwarf willow (Salix spp.), and bog blueberry, (E uliginosum). We used 3 types of traps to collect specimens: small, homemade Sherman-style live traps, 1-gal can pitfall traps, and Museum Special snap traps. We used cheese, peanut butter, and sunflower seeds for bait in the live and snap traps. We placed traps in the dry tundra/shrub edge habitat on Eagle Island and in meadow, wet tundra, mixed forest, and meadow/ mixed forest edge habitats at the Agulukpak River. We used only snap traps in wet tundra, but used all 3 trap types in the remaining habitats. In each habitat type, we set 10 to 15 snap traps at 2.5-m intervals along a single transect. Five live traps and 8 pitfall traps were placed in no particular pattern within habitats. Traps in non-edge habitats were set at least 20 m from habitat edges. We recorded species, standard measurements, location, date, and habitat type for each animal captured. Voucher specimens for each species collected were identified by Dr. Johnson, Emeritus Professor of Zoology, University of Idaho, Moscow and deposited in the museum there. We collected 41 small mammals in habitats near the Agulukpak River: 30 shrews (S. monticolus, S. cirlereus, and pygmy shrew [S. hoyi], 3 C. rutilus, and 8 Z. hudsonius. One specimen of C. rutilus was collected on Eagle Island and 1 M. erminea was collected on the mainland adjacent to the island (Table 1). We observed a colony of arctic ground squirrels (Spermophilus parryii) in August on Lake Nuyakuk and saw red squirrels (Tamiasciurus hudsonicus) in several locations throughout the Park. A colony of little brown bats (Myotis lucifugus) lived in the Agulukpak cabin. The cabin is located at the head of the Agulukpak River and houses the Wood-Tikchik State Park volunteers. Pitfall traps were much more effective than snap traps in capturing shrews; of the 30 Sorex collected, 28 were caught in pitfall traps. Live traps were ineffective in capturing specimens for unknown reasons; none of the various baits placed inside the traps was ever disturbed. That only 1 C. rutilus was collected on Eagle Island in 255 trap nights suggests that species richness and abundance of small mammals on the island were low. This is the 1st record of