Western Grasshopper Sparrow – State Wildlife Action Plan

The Grasshopper Sparrow is a small, enigmatic, and inconspicuous grassland bird which can be easily overlooked, but is considered rare in Oregon. Occurrence of the species is often erratic, as small populations may arrive to an area for nesting, move away, then return a few years later. It is difficult to detect due to secretive behavior. It has a characteristic insect/grasshopper-like song delivered from a fence-post or shrub. It is small ‘flat headed’ sparrow with short tail, prominent black eye, and large bill. The Grasshopper Sparrow has a cream-buff breast, white belly, dark crown streaked with buff-white crown stripe, orange-yellow between bill and eyes – sometimes extending thinly over and behind eye; grayish streaked nape, back streaked with chestnut-rust and blackish, and the edge of the wings are yellow.
Only one subspecies of Grasshopper Sparrow is known to occur in Oregon, the Western Grasshopper Sparrow (A. s. perpallidus).

Overview

Species Common Name Western Grasshopper Sparrow
Species Scientific Name Ammodramus savannarum perpallidus
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.

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.

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 …

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

Grasshopper Sparrows prefer dry grassland and pasture habitats with low to moderate grass height and little shrub cover. They need large areas of suitable habitat to thrive. Among grassland birds that occur in Oregon, it is one of the most dependent on native perennial grasses and occupies a narrow niche including bare, sparsely vegetated ground with relatively short vegetation. In Western Oregon in particular, they are dependent on habitats without shrubs and trees that invade grassland habitat in areas with a history of fire suppression historically used by Indigenous people.

In the Willamette Valley, Western Grasshopper Sparrow territories have more grass cover but less cover from forbs, shrubs, and trees compared to areas occupied by Western Meadowlarks. Their nests are often located in lightly grazed pastures and fallow fields. They are also found in recently restored and remnant prairie areas around Eugene. In the foothills of the Blue Mountains in Morrow County, these sparrows are found in remnant bunchgrass stands that are not intensively grazed.

Limiting factors

Grasshopper Sparrows are uncommon and locally distributed in Oregon. Loss of their grassland habitat due to conversion and shrub/tree encroachment may be the most important factor limiting their abundance in Oregon. Nesting failure due to timing of land use practices (e.g., mowing, haying, spraying) also impacts this species.

Data gaps

• Assess distribution and abundance.
• Investigate habitat relationships, including the effects of habitat patch size on abundance and productivity.
• Identify and describe planting mixes that may favor this species.
• Assess the impacts of grazing and agricultural management on productivity.
• Assess wintering locations for Oregon birds.
• Study demographics, movement, and site fidelity.
• Specific information about barriers to dispersal and migration for Western Grasshopper Sparrow in Oregon is needed.
• Evaluate impacts from wind energy development.

Conservation actions

• Maintain or restore grassland habitat.
• Increase plant diversity to promote greater insect diversity.
• Maintain high percent native grass cover and <10% shrub cover in patches >20 acres.
• Delay mowing and other field management until after July 15 at known nesting areas.
• Control key invasive plants to maintain habitat suitability.

Key reference or plan

Status Assessment and Conservation Plan for Grasshopper Sparrow. Read here

PIF Focal and Imperiled Species. Rockwell et al. 2022. Read here

Population and Habitat Objectives for Landbirds in Prairie, Oak, and Riparian Habitats of Western Oregon and Washington. Read here

The Willamette Valley Landowner’s Guide to Creating Habitat for Grassland Birds. Read here