by Steve Elston, TNC volunteer

Sagebrush at the Moses Coulee preserve. Photo by Lane Justus.

The sagebrush habitat of The Nature Conservancy’s Moses Coulee and Beezley Hills Preserves comes to life with song in the spring. Male birds sing on their nesting territory to attract females and warn-off other males. While beautiful to the human ear, this song is serious business for these birds.

In this post we explore some of these sagebrush songsters.

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Birds of Moses Coulee

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The Habitat

The Moses Coulee & Beezley Hills Preserves protect a significant area of rich sagebrush habitat. Historically, about 1/3 of Washington was covered in sagebrush, but now only about 40% of this threatened ecosystem remains.

Plant communities dominated by sagebrush are a core component of the shrub-steppe ecosystem, a harsh environment. Winters are cold, often with significant snowpack. Summers are long, hot, and dry. As a result, this environment is dominated by shrubs, such as stiff sagebrush (Artemisia rigida) and big sagebrush (Artemisia tridentata), and a multitude of native bunch grasses occupy the open space between the shrubs. Trees are confined to areas along creeks, seeps, and springs. Thus, the birds breeding in this harsh environment have adapted in a number of ways.

Sage Thrasher

The sage thrasher is a bird of the open sagebrush. Male sage thrashers are less secretive than other shrub-steppe birds, often singing from the highest perch available.

Sage thrashers are opportunistic foragers. During nesting season you might see one running in the open spaces between shrubs, hunting for their preferred food of insects and spiders. Sage thrashers also eat berries when available.

Fun fact. Like all thrashers, sage thrashers are in the Mimidae family, the mimics, which includes the new-world mockingbirds.

Both female and male sage thrashers work to build nests. The nest is usually placed low in the densest sagebrush. This careful placement is thought to protect the nest from both aerial predators and the intense summer sun. Sage thrashers are secretive near their nest, often approaching the nest by walking on the ground rather than flying.

During breeding season, male sage thrashers perch high in a large shrub and sing. You can often hear two male birds counter-singing (singing back and forth) along the boundary of their territories. You might see a male performing a courtship display with a low circular undulating flight pattern. Hear the sage thrasher’s long liquid song by clicking below:

Accessible at www.xeno-canto.org/512251.

Sagebrush Sparrow

The sagebrush sparrow is aptly named. This bird has a strong affinity for nesting in the sagebrush habitat. In the spring, the song of the sagebrush sparrow rings through the sagebrush of Moses Coulee and Beezely Hills.

In all respects, the sagebrush sparrow is perfectly adapted to life in the shrub-steppe. Look carefully during breeding season, and you might see sagebrush sparrows hunting on the ground or low in the brush for insects and spiders. These birds are opportunistic feeders and will consume berries and small fruit, along with succulent parts of plants, in any season.

Dense shrub cover at Moses Coulee. Photo by Lane Justus.

The sagebrush sparrow’s nest is an open cup, placed low in a shrub or even on the ground. Sagebrush sparrows prefer to place their nests in the cover of large, thick sagebrush. This location protects the nest from the midday sun and hides it from the prying eyes of predators.

Male sagebrush sparrows have a strong affinity for their territory. Male birds are known to return to, and defend, the same patch of sagebrush nesting territory for their entire lives! The same male might be found on the same breeding territory for up to 6 years.

The sagebrush sparrow typically sings its song from a perch in a large sagebrush plant. Hear the distinctive song by clicking below:

Accessible at www.xeno-canto.org/468609.

Brewer’s Sparrow

The life of the diminutive Brewer’s Sparrow is strongly linked to the shrub-steppe. These slim birds are among the smallest sparrows found in North America. Despite their size, Brewer’s Sparrows are likely the most common bird that you will see or hear in the shrub-steppe during spring.

Important fact. The Brewer’s Sparrow, along with Sagebrush Sparrows, Sage Thrashers and Sage Grouse, are sagebrush obligates. With the exception of the Timberline subspecies of the Brewer’s Sparrow, these birds can only reproduce in the sagebrush habitats. Therefore, their continued existence is tied to areas like the Moses Coulee & Beezley Hills Preserves.

During breeding season, Brewer’s Sparrows forage low in the shrubs of this habitat. They eat a variety of insects and spiders.

Brewer’s Sparrows prefer to place their nests in dense large sagebrush, away from open ground. These birds have a preference for big sagebrush (Artemisia tridentata). The dense sage cover keeps the nest hidden from both predators and intense sun.

The song of the male Brewer’s Sparrow is unmistakable. It is said to sound like an old-fashioned lawn sprinkler. Click below to hear this unique song.

Accessible at www.xeno-canto.org/342060.

Vesper Sparrow

The Vesper Sparrow is an aptly name shrub-steppe bird with a sweet tinkling song. Unlike the other sagebrush habitat birds that we have explored, the Vesper Sparrow feeds and breeds primarily in the grassy open spaces between stands of shrub.

Vesper Sparrows forage on the ground. These birds will scratch the soil in open areas to find seeds, particularly grass seeds. Vesper Sparrows will also pluck insects found low in shrubs or grasses.

Being a bird of the open ground, Vesper Sparrows build their nests in open, grassy areas. These nest are often a shallow depression in the ground surrounded by grass and twigs.

Fun fact. The male Vesper Sparrow will start singing at dawn, but often continues singing well into the evening. This evening song gives rise to this bird’s name.

Since they spend most of their life on the ground, Vesper Sparrows are more often heard than seen. To hear the melodic song of the male Vesper Sparrow click below.

Accessible at www.xeno-canto.org/539420.

Bunch grasses in open spaces between shrubs at Moses Coulee. Photo by Lane Justus.

Birds on the Move

All of birds discussed here are migratory. They spend their winter months in the southwest United States and northwest Mexico. In February these birds start an annual migration to their nesting sites, including sites at the Moses Coulee & Beezley Hills Preserves. From April into the summer, these birds can be found on their breeding territories. Once the summer breeding season is over, the birds return to their winter habitat.

The ebird web site contains sightings for thousands of bird species from around the world, mostly made by citizen-scientists. Animated maps showing the annual migration of many species can also be found on ebird. You can find the maps for the sagebrush songbirds discussed here by clicking the links below:
- Sage Thrasher
- Sagebrush Sparrow
- Brewer’s Sparrow
- Vesper Sparrow

Climate change and shrub-steppe birds: The shrub-steppe is a threatened ecosystem. As a result, many sagebrush-dependent songbirds are losing habitat. According to a study by National Audubon Society scientists, for just 1.5 C of average temperature increase, these species will lose significant parts of their current breeding ranges. Click to links below and scroll down to see effects of other climate change scenarios.

Sage Thrasher, 30% loss
Sagebrush Sparrow, 23% loss
Brewer’s Sparrow, 24% loss
Vesper Sparrow, 32% loss

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