Squirrelorgy In The Bathroom Window?

What the heck is going on with the squirrels on our bathroom window ledge?? We've had one squirrel trying to make a nest on the ledge and the wind and branches periodically knock it down. A month ago, I had two squirrels hanging out there. But on and off all summer, some squirrel has been hanging out there more often than not. Today, I stepped into the bathroom and could see one squirrel head and it looked like a second one was there too. I grabbed my camera and tried to sneak a photo--check it out, there are three.

One of the squirrels heard the camera and jumped away, only to reveal a FOURTH squirrel. The little dude on the right was busily grooming the squirrel on his left. I love the paw on the back of his buddy, looking at the squirrel hopping away on the branch as if to ask, "What's up bro'?"

When they all realized there was a camera, they hopped away, but gave me that disaffect youth look. As if I was the old person telling them to loiter elsewhere.

So, what is going on here? Which one of you readers out there knows about squirrel behavior--what would make four squirrels hang out on a ledge while sleeping and grooming each other? They all looked fully grown, I don't think they were young ones, but maybe they are? Anyone have any clues as to why they're hanging out together?