Date: 9/3/20 9:43 am From: Joel Geier <clearwater...> Subject: [obol] Fwd: Grassland sparrows (Lark, Vesper & others) near Airlie in s. Polk Co.
From: "clearwater" <clearwater...> To: "Mid-Valley Nature" <mid-valley-nature...> Sent: Thursday, September 3, 2020 9:41:34 AM Subject: Grassland sparrows (Lark, Vesper & others) near Airlie in s. Polk Co.
This morning after checking for banded Vesper Sparrows at a Christmas tree farm near Airlie in s. Polk County, on my way out I happened across one or likely two Lark Sparrows that flew up from some shrub-sized Xmas trees right along Sauerkraut Rd. They were together and both flashed similar tail patterns as they flew but only one sat up in view on the pasture fence on the north side of the road. It looked like a hatch-year (first fall) bird based on the relatively subdued facial pattern.
According to historical accounts, Lark Sparrow was a moderately common nesting species in this region in the late 1800s and early 1900s. Arthur Roy Woodcock, writing in a bulletin of the Oregon Experimental Agricultural Station published in 1902, mentioned finding three nests in the Corvallis area. However, since the 1920s this species has become scarce in the Willamette Valley, and (like Lewis's Woodpecker) has been seen only as migrant or wintering birds in recent decades.
Earlier in the morning, I found two separate flocks of Vesper Sparrows on private land (accessed by permission), adding up to about 15 birds. They were in areas where we've seen Vesper Sparrows throughout the breeding season, but none of them were banded, so I suspect that most or all of them were hatch-year (first-fall) birds that hatched locally.
At other Vesper Sparrow monitoring sites that were monitored more intensively this year (so there were more banded fledglings), nearly all of the banded birds still around since mid-August have turned out to be hatch-year birds. It seems as if the adults begin their migration earlier in the season, along with juveniles from early nests, while juveniles from later nests may stay on their natal sites well into September.
Other grassland sparrows this morning included fair numbers of Savannah Sparrows, and a couple of flocks of White-crowned Sparrows around the edges of the taller Xmas trees. The White-crowns were also mainly juveniles with rusty crowns, though I saw one adult.
I didn't find any Chipping Sparrows -- seems like the ones that were around during nesting season have mostly cleared out.