bird sex

Caution, this post really is about sex.
I am noticing something that I have not noticed in other springs...crazy, wild and obsessive bird mating. Evan and I were in the back of the holler and we saw this titmouse couple, chasing and then coupled together in flight and staying that way for a long, long time....down the creek and back up and down again, then once around the pond for good measure.
We were impressed.
I didn't give it any more thought, then this morning, I watched phoebes doing it, then a couple of chickadees, more phoebes, titmice and some hummingbirds....The seemed to stay together longer than what I have observed before and were generally making more of a commotion than what I consider normal. And I had to ask myself, why is everybody doing this in my front yard on this particular morning?
I have seen birds mate before, but this behavior is different. Kinda reminds me of the goings on of the current younger generation downtown Nashville in the club scene....extreme, frantic, and a different person every night.
Then I saw something that really wrinkled my forehead in pondering.
I saw a carolina wren pair. They were making alot of noise and commotion, doing what they were doing....a male cardinal came swooping in, I thought to break up the commotion. But he ran off the male wren and then he jumped on the female wren like a big rooster on a little banty hen. When he finally fisnished what he was doing and it was not a "mutual in flight thing" like the other pairs, he flew off of her. She was pretty ruffled up and hid under the forsythia bush for a while, regaining her composure before she flew off.
Is bird rape normal? is this rape, if it is not your species? Has this been going on all along and I just didn't notice?