Wild bird behavior

I love my backyard. It is big enough so I can putter around gardening, swim in the pool, watch the dogs play or simply sit and enjoy a cup of coffee and listen to the birds sing.
I have so many different varieties of birds in the backyard, I can't even identify them all but the basics are here: crows, blue jays, mockingbirds, herons, and cardinals. I did once have a Mallard Duck in the pool but he flew away.
A couple of weeks ago, I kept hearing a noise that sounded like pecking on the sliders which lead to the outside. I have three different sets of cardinals which have nests in my backyard and seeing the females, pecking at my sliders was a behavior I had never observed in them before.
So I went and researched why they were doing this. It seems in the spring and early summer, they are protecting their nests and when they see themselves in windows, they believe there are other birds they need to defend themselves and their nests from.
This is not only the males, but the females participating in this action. So to protect them, I got a bar of soap, biodegradable of course, and streaked the sliders with it.
Although I love to watch them and listen to their song, I don't want any of them hurt.