I had suspected that my avian nemesis was a mockingbird, and in talking to a friend of mine who, it turns out, has the exact same problem, my suspicions were confirmed.
So listen: it is a sin to kill a mockingbird, according to Atticus "Whose Side Are You On Let's Check Your Last Name" Finch, because they never do any harm to anyone. Well I AM BEING HARMED.
I did some Googling and I am certainly
not the only one with this problem. One person suggested
this as a solution, which I will definitely look into.
It also bears mentioning that there are a number of vegetarians who want to kill their own unwanted mockingbirds. Maybe I'll start a mockingbird assassination service. And before I shoot them I'll say "HEY BIRD! MOCK THIS!"