As soon as I step out of the car, I hear them. Four to six singing birds, no matter where I stop along the farm road that winds through the pastures of Michael Horton and Sandy Allen's farm.
The Oregon Vesper Sparrow dominates the morning airwaves here amid a chorus of Western Meadowlarks, Western Kingbirds, Ash-throated Flycatchers, Lazuli Buntings, and Grasshopper Sparrows. The sparrow's melodious song often fills the evening hours, too, inspiring its name and signaling the end of another day.
Despite the ubiquity of the sweet song in this particular spot, however, the Oregon Vesper Sparrow is not a common bird. It is one of our rarer birds in western North America. A subspecies of the more-common Vesper Sparrow, it was once widespread among the grasslands and savannahs west of the Cascade Mountains. The bird's estimated population now numbers fewer than 3,000.
I first became interested in the sparrow about 20 years ago, intrigued by its status as a bird of concern. At the time, I did some initial studies on habitat and nesting in the Willamette Valley of western Oregon. But only in the last few years have I have begun to focus on their conservation. This is due in large part to widespread concern about the prairie and savannah habitats in which this rare bird historically lived, and the fact that most of these lands are privately owned.
The Oregon Vesper Sparrow's demise tracks closely with settlement patterns in the lowland valleys of the Pacific Northwest. Prairies and savannah dominated these areas when early Europeans first arrived. The settlers quickly realized these were the best places to live and to farm.
Judging by what we see today, the Oregon Vesper Sparrow likely adapted somewhat from living on prairies and savannahs to the small farms and pastures of the early settlers. However, over the next century, the native prairies and savannahs nearly disappeared. And since the 1950s, those small farms and pasturelands have given way to the large farms and commercial croplands we see today.
But Oregon Vesper Sparrows did not adapt to cropland agriculture as they did to pastures. That is what has kept me busy the past two breeding seasons: I am trying to find the remaining populations and understand why they persist in those places and not others. Just as importantly, I want to understand the major threats the remaining birds face.
The Umpqua Valley of southwestern Oregon, where Michael and Sandy live, is home to roughly two-thirds of the Oregon Vesper Sparrow's population. Large ranches of grazing livestock command the hilly landscape, and cropland is generally confined to smaller areas in the bottomland fields. Scattered oak trees and shrubs dot the grassy slopes, meadows, and swales. Light to moderate grazing, along with shallow and rocky soil, keeps vegetation from growing tall and dense. It is a perfect setting for vesper sparrows.
Michael and Sandy bought their ranch here in 1993. In the years since, they have been diligent stewards of the land, allowing their neighbor to graze cattle in a sustainable manner on most of the property.
They knew nothing about the Oregon Vesper Sparrow until my inquiry this year to work on their property. But we now know they have the densest population I have seen: approximately 30 pairs across 150 acres.
It's a good thing there are places like this, because the picture is pretty grim elsewhere. There are only a few breeding pairs of Oregon Vesper Sparrows on Vancouver Island, British Columbia, and the northern Puget Sound ecoregion. Fewer than 500 birds are left in the Puget Lowlands and Willamette Valley ecoregions, and maybe only 200 birds in the Rogue Basin.
It's not hard to see why this is so. The valleys of the Pacific Northwest west of the Cascade Mountains are among the fastest-growing population centers in North America, and the historic prairie and oak landscape continues to be the place where people want to live. The region is also dominated by agricultural cropland, including recent development of vineyards, which prevent Oregon Vesper Sparrows from using the land.
The future of this bird will likely depend on significant restoration of historic prairie and savannah habitats to provide new opportunities to create or expand populations. There may even be the need for the bird to be listed under the Endangered Species Act to ensure protection and enhance conservation efforts.
At Bald Hill Farm, near Corvallis in the southern Willamette Valley, some of this habitat restoration is happening now. The Greenbelt Land Trust, which owns the roughly 600-acre property, began a large restoration effort this summer. Ecologists who specialize in habitat restoration are converting areas of degraded savannah and dense oak and oak-and-fir woodlands and forests to oak savannahs and open woodlands—landscapes that draw vesper sparrows and many other rare and declining species.
I have been mapping territories of approximately 25 pairs of Oregon Vesper Sparrows on this property over the last two years. The restoration will open up another 20 to 30 acres adjacent to four or five existing territories for the bird.
Amid the real potential for extinction of this bird, efforts like those of Michael Horton and Sandy Allen and the Greenbelt Land Trust are bright spots. They provide hope that in the years to come, the Oregon Vesper Sparrow will once again be a prominent songster on the grasslands and savannahs of the Pacific Northwest.
Bob Altman is ABC's Pacific Northwest Conservation Officer. He has a degree in wildlife biology from Eastern Kentucky University. He has been active in Partners in Flight since its inception, with several committee positions at state and regional levels, including his current position as Chairperson of the Oregon-Washington chapter. Before coming to ABC, Bob worked as an independent ornithologist conducting avian research and monitoring under the business name of Avifauna Northwest.