Silver-haired Bat – State Wildlife Action Plan

The silver-haired bat is a small vespertilionid, with adults ranging from 92-115 mm in length, weighing 8.1 to 11 g with a tragus length of 5-9 mm. Their distinctive fur coloration, consisting of silvery or frosted hairs, makes them unlikely to be confused with other bat species in Oregon. Their interfemoral membrane is furred above the basal half. Wingspan, area, and body mass are important contributing factors to flight speed and maneuverability, and therefore foraging habits.Their wingspan on average is 27-31 cm, which is long compared to other species.

Overview

Species Common Name Silver-haired Bat
Species Scientific Name Lasionycteris noctivagans
Federal Listing Status Species of Concern
State Listing Status Sensitive

Ecoregions

Blue Mountains

Located in NE Oregon, the Blue Mountains ecoregion is the largest ecoregion in the state. It provides a diverse complex of mountain ranges, valleys, and plateaus that extend beyond Oregon into the states of Idaho and Washington.

Coast Range

Oregon's Coast Range, known for its dramatic scenery, is extremely diverse, with habitats ranging from open sandy dunes to lush forests and from tidepools to headwater streams. It follows the coastline and extends east through coastal forest to the border of the Willamette Valley and Klamath Mountains ecoregions

Columbia Plateau

The Columbia Plateau ecoregion was shaped by cataclysmic floods and large deposits of wind-borne silt and sand earlier in its geological history. It is dominated by a rolling landscape of arid lowlands dissected by several important rivers, and extends from the eastern slopes of the Cascades Mountains, south and east from the Columbia River to the Blue Mountains.

East Cascades

The East Cascade ecoregion extends from the Cascade Mountains' summit east to the warmer, drier high desert and down the length of the state. This ecoregion varies dramatically from its cool, moist border with the West Cascades ecoregion to its dry eastern border, where it meets sagebrush desert landscapes.

Klamath Mountains

The Klamath Mountains ecoregion covers much of southwestern Oregon, including the Klamath Mountains, Siskiyou Mountains, the interior valleys and foothills between these and the Cascade Range, and the Rogue and Umpqua river valleys. Several popular and scenic rivers run through the ecoregion, including the Umpqua, Rogue, Illinois, and Applegate rivers. Historically, this ecoregion is known …

Northern Basin and Range

The Northern Basin and Range ecoregion covers the very large southeastern portion of the state, from Burns south to the Nevada border and from the Christmas Valley east to Idaho. It is largely a high elevation desert-like area dominated by sagebrush communities and habitats.

West Cascades

The West Cascades ecoregion extends from east of the Cascade Mountains summit to the foothills of the Willamette, Umpqua, and Rogue Valleys, and spans the entire length of the state of Oregon. It is largely dominated by conifer forests, moving into alpine parklands and dwarf shrubs at higher elevations.

Willamette Valley

The Willamette Valley ecoregion is bounded on the west by the Coast Range and on the east by the Cascade Range. This long mostly level alluvial plain has some scattered areas of low basalt, and contrasts with productive farmland and large urban areas. It has the fastest-growing human population in the state resulting in challenges due to land-use changes.

Special needs

Silver-haired bats inhabit late-successional conifer forests. They use large snags and hollow trees for day, night, and maternity roosts. They may be found in other habitat types during migration. Silver-haired bats are an insectivorous tree-roosting bat, and tend to be solitary, although there are records of multiple females roosting together in Oregon.

Limiting factors

Silver-haired bats have low reproductive rates. They are vulnerable to habitat loss, including reductions in late-successional conifer forests and their components (e.g., hollow trees and large, newly-dead snags). Migratory behavior increases the vulnerability of this species to habitat changes and wind turbine-related mortality in the spring and fall. Mortality of mature females in the spring may be particularly problematic. Silver-haired bats have been documented carrying the fungus that causes white-nose syndrome.

Data gaps

• Assess distribution, abundance, and trends.
• Describe population dynamics.
• Improve understanding of migration patterns and habitat use.
• Evaluate the impacts of wind facilities on migratory bats.

Conservation actions

• Maintain late-successional conifer habitat.
• Maintain and create large-diameter hollow trees and snags.
• Implement impact reduction strategies (e.g., operational minimization) at wind energy facilities to reduce fatalities.
• Investigate other best management practices for implementation at wind energy facilities.
• Continue white-nose syndrome surveillance.
• Follow most recent decontamination protocols to prevent spread of the fungus that causes white-nose syndrome, Pseudogymnoascus destructans

Key reference or plan

North American Bat Monitoring Program in the Pacific NW. Read here