The Horned Lark is very widespread in North America. I first encountered the species on the dusty roads of Dillon County, South Carolina as a youth. They are still there today. More typically, they inhabit the desolate places of the interior. You can see flocks of them flying around the snow plains when nothing else is about. Despite the rigors of nesting in places where the footprint of bare ground rivals the footprint of vegetation, though, they are legion. They are so often the only act in town.
But all Horned Larks are not the same. Just in North America, they have split into 21 subspecies, according to Peter Pyle. One of these, the Streaked Horned Lark, Eremophila alpestris strigata, is endangered. It is adapted to the wet prairies of the West Side of the Pacific Northwest. This is hardly a desolate place. It is lush, but the Streaked Horned Lark, isolated in the Willamette Valley and the Puget Lowlands, found a way to make a living in the fire-maintained prairies, and along the coast. It was once fairly common from British Columbia south to Oregon. Today it is down to a couple of thousand birds at best, victim, like many other plant and animal taxa endemic to these prairies, of the wholesale conversion of prairie to farmland in the nineteenth century. Stalwart efforts are saving the plants, but that seems easier than "recovering" the animals, who must cope with widespread pesticides as well as habitat loss.
The birds singing for us here are in all likelihood Streaked Horned Larks. To begin with, they are the kind of Horned Lark expected in this place. Further, one of the photos shows the dark streak down the middle of the tail that is a peculiarity of this subspecies. (This streak adorns an extremely long upper tail covert, which nearly covers the black tail.) The eastern subspecies have dark streaks, too. The West Side is the only place in the west that equals the east in rainfall, and that leads to heavy pigmentation, making strigata stand out. These larks could be found along Green Hill Road opposite the Eugene airport in the summer of 2011 and for several years before that. To the east was a field that was kept in low-growing clover, which seemed to fit the lark need for sparse vegetation. They also foraged on the side of, and even in the middle of, the paved road. It was a noisy place, with jets taking off and trucks barreling down the highway, so I had to filter the sound before uploading it. Thus liberated from the noise at the bottom of the spectrum, the flight songs of the larks are loud and clear, the way they were before the arrival of the machines.
The Horned Lark is the only species of true lark (Family Alaudidae) that occurs naturally in the New World. It's the reverse of the situation with wrens. The New World has many wren species, the Old World has many lark species. In both cases a single member of a family that already had produced many species ventured across the Bering Land Bridge and moved into a new world. Both spread across the northern continents but not into the southern ones. Both are distinctive and one could say beloved members of their hemispheric avifaunas. Long live immigration.