Western Meadlowlarks spend the Winter around here, as do Eastern Meadowlarks. The only reliable way to tell them apart is by their song. In fact, it was because their songs are so different that they were considered a different species! The Eastern Meadlowlark's song is composed of high pitched whistles, and sounds nothing like this gurgly guy, who was recorded in May 1999 near the Salinas River of Central California.
A bird mutters to himself in a "whisper song" that bears little relation to the other sounds this species makes - sung from atop a power pole near Cornville, Arizona, 5/99.