A flock of about 10 White-throated Sparrows has been hopping and scratching around the yard for a few days. They sing first thing in the morning, last thing in the evening, and off and on all day.
Now their pretty song (YouTube video here) is really stuck in my head.
White-throated Sparrows sing a pretty, thin whistle that sounds like Oh-sweet-canada-canada or Old-Sam-Peabody-Peabody. The whistles are even but typically move slightly up or down in pitch by the second or third note. The whole song lasts about 4 seconds. White-throated Sparrows sing often during the breeding season, even in the middle of the day, and on their winter range as well.