It surprises me that I haven't had Lewis do this yet. It seems like the thing he would do all the time. I'll have to have him do it again in the future.
Also, it is very true that "titmice" is not correct, but I'm not in the habit of correcting people on it. I mean, it just sounds right, and it feels right, so it's not something that I'm a stickler about. I do correct people about other plurals, though, like "octopi." No. It's not "octopi." It's "octopuses" or even "octopodes" if you want to be fancy.