Returning to their breeding grounds

The marina where I walk Devil Dog is a gay male cruising spot. There used to be restrooms where they got their freak on, but they tore those down to try to prevent the shenanigans.
It hasn't stopped them though. The area is littered with condom wrappers.

I told right-wing co-worker about it.

"They are like birds who keep flying back to the same breeding ground," I said.

"Yeah," said he. "They're swallows."