Black Tern – State Wildlife Action Plan

The Black Tern, Chlidonias niger, is Oregon’s smallest tern with black head body and gray wings during the breeding season. Sexes are both similar but the males are generally larger. Bill black; legs blackish red.

Overview

Species Common Name Black Tern
Species Scientific Name Chlidonias niger
State Listing Status Sensitive (pending)

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.

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

Black Terns are found in shallow freshwater marshes, flooded meadows, and wetlands with emergent vegetation and are often associated with bulrush, sedge rush, or tufted hairgrass/rush habitats with some standing water. Emergent vegetation often supports or anchors the small, flat-floating nest platform. Seasonal water levels, prior to and during nesting/fledging, are critical to nesting success.

Limiting factors

Black Terns nest on the edges of lakes or shallow inland wetlands, often among emergent vegetation. Their nesting areas are vulnerable to drought, flooding, and fluctuating water levels, which can lead to nest abandonment. They are also susceptible to disturbance from human activities. Black Terns frequently move in response to changing water levels. Additionally, they are vulnerable to the impacts of insecticides, which can reduce the availability of their invertebrate prey.

Data gaps

• Identify landscape-level breeding and post-breeding habitat needs for responding to annual site-specific changes in water levels and forage availability.

Conservation actions

• Protect suitable nesting areas and occupied sites.
• Maintain wet pastureland within proximity to nesting areas to provide foraging areas.
• Limit disturbance in known breeding areas.
• Manage for pollution concerns including organochlorine pesticides, lead, and mercury.

Key reference or plan

Waterbird Conservation Plan for the North Americas: Waterbird Conservation Plan. Read here

Intermountain West Waterbird Conservation Plan. Read here