Not sure if this is the right place to ask, but I just looked out the window and saw what I can only describe as hundreds of bees flying in little loops in my backyard (some near the ground, some 20 feet up). Some have been lightly pinging against the windows. At first I thought they were just passing through, but after watching them for a while they seem to be coming from the only large tree in the yard, which I didn't even know had bees living in it. As far as I know no one's been near that tree in the past few hours, and while it's slightly windy it's definitely not anything extreme, so I don't know what might have triggered this.

Anyone know what might have caused this, and if there's anything I can do to help them, or if it's just something that happens and will die down? It's been about 10-15 minutes and they're still about the same as when I first noticed them.