I had a hard time choosing a song for today. Not satisfied with the material I had on the shelf, I opted for a morning of recording at Bear Island Wildlife Management Area, in South Carolina's ACE Basin. If you will go to Ebird Checklist S68026174, you can check out the runners-up for today: the stolid monotony of a Chuck-will's-widow song, a very complex sound made by Red-winged Blackbirds, the surprisingly loud chuckle of the Least Bittern, and a song duel by a couple of nopareils, adult male Painted Buntings. None of those is here, because, before I left, I heard the neighborhood mocker down the street. It was 4:30 a.m., but that's not a problem for a mockingbird. They'll sing all night, and keep you awake if you happen to have a resonating chimney to sing from.
He has been singing a lot lately. I heard him doing the Eastern Phoebe the other day, which inspired me to record him for a few minutes. Now he's singing at night, too. He must be looking for a mate. We could speculate about that, but let's talk about syntax instead. We have here, today and yesterday, the juxtaposition of two different singing styles. The California Thrasher produced long rambling arias that lasted many seconds and that were separated by many seconds of silence. This mockingbird produces tight, highly-organized clusters of sound that typically last a second or so, with equally short silent breaks between them. And if you look at each cluster, you will see that it is constructed by stringing together three or more copies of a short phrase. Three is important. If most clusters have three or more identical units, the singer is a Northern Mockingbird; if that number is two, the bird is a Brown Thrasher. Most other mimids, such as the California Thrasher, do not follow such rigid rules.
"Syntax" is another word for combination rules. Birders depend on those rules to distinguish singing Brown Thrashers from singing Northern Mockingbirds. The birds probably do, too. And if they get it wrong, they might not get a mate. I'm wondering if this male repeats identical clusters too much. Just a pattern that I noticed that I had never noticed before. I could test the hypothesis by counting how many types of sounds he has in his repertoire, and whether he sings with immediate or eventual variety (see the Varied Thrush). Then I could compare my counts from this bird to counts made from online resources. Or maybe that's something you'd like to do. Feel free to get your feet wet.