In your damning of deer, you left out that they host ticks.
A big problem in coastal New England.
Yet birds are but one of the necessary intermediate hosts for tick nymphs that grow up to spread Lyme.
I have deer everywhere here and haven’t seen a tick all year.
Why?
The birds who usually frequent my backyard are not there because I stopped feeding them out there.
Figured out several years ago, the bird/tick connection.
Used to have to spray the yard after every rain to keep the dogs safe.
Never spray it now.