The bird with a black cap is not a Blackcap. The bird with a red-brown cap is a (female) Blackcap.
The bird with a black cap is a Great Tit.
Then they came to blows (pecks) flying six inches into the air.
"Are you a Bluecap?"
The male Blackcap finds it easier to tolerate other diners . . .
unlike the hen, he is not chased away by the resident Robin.
"You've a blacker cap than I have."
Sometimes he swears at intruders.