From the base of the tower, the highest point in Mt. Auburn Cemetery, you can usually see Boston. But late this afternoon all you could see was low clouds and maybe a little fog in some of the hollows of Cambridge. It was a lousy day to go looking for warblers, but this was the only free day I had.

I walked around for half an hour and the only birds I could see well enough to identify were some American Robins. The light was bad, and mostly I just saw silhouettes. I could hear birds all around me though. Good birders can identify hundreds of birds by ear. Not me; all I know is a couple dozen of the more common ones. Mewing: Catbird. Konk-a-ree: Red-Winged Blackbird. Cheeriup, cheeriee: American Robin. A few others.

After an hour I had managed to see a few birds, but no warblers. The whole reason you go to Mt. Auburn Cemetery in the spring is to see warblers; it’s nationally famous for being a spring warbler trap. I was about to leave when I heard a lazy song that sounded something “zee zee zee zee zoo zee,” the “zee”s all on one note, and the “zoo” perhaps a major second lower. I had been camping up in Maine early one July, in a campsite in a pine grove, and I used to hear that lazy song every morning right at sunrise: “zee zee zee zee zoo zee” over and over again; or sometimes “zoo zoo zee zoo zee.” I had finally tracked the bird down: Black-throated Green Warblers who had been nesting right next to my campsite. Here they were in Cambridge, lazily calling from somewhere up in one of the trees.

“Zee zee zee zee zoo zee.” I tried to figure out where the bird was sitting. I walked around in a big circle, trying to triangulate. “Zee zee zee zoo zee.” There were at least two; one of them seemed to be moving further away. Once I thought I had the nearer one spotted; I brought my binoculars up; but then I heard it from the next tree over, lazily calling “zee zee zee zee zoo zee.” At last I gave up, and went back to the car. You don’t always have to see things to know they’re there.

For my mom, who was a birder; today would have been her 82nd birthday.