I continue to watch Rufus the hummingbird throughout the day. My office window looks out over the backyard so it's a pleasant distraction.

It turns out Rufous hummingbirds are very territorial. Rufus regularly chases away other hummingbirds. Our neighbors also have a hummingbird feeder which is part of his territory. He zips back and forth between the different feeders, and dive bombs any other hummingbird who dares take a sip. I've now know his attack trill and quickly look up when he's on the attack.