I'm having one right now! One little Rufous has driven off all my other birds. I have to go stand by the feeder so they can come in and load up w/o this bird attacking them. I may have to get a badminton racquet.
The black-chinned one is trying to do that here, too, but so far the anna's far outweigh the pair in sheer numbers! My male is sooo sneaky - I spent quite a bit of time out yesterday with just the one "spot" open (got some nice shots - thank you for the tips!) had to go inside for less than a minute, came back out and there he was guzzling down the nectar, I get to the right angle to catch his blue throat - and he's outa' there, never to return LOL, at least for the rest of my available time but I will prevail!!
The best time is dusk when they have to feed. Set the camera speed=100-250, ISO=100-400, Aperture to ~f/8 Make sure your flash sync speed is set to 1/320FP. Set the strobe to manual and the setting to between 1/8 power to 1/64 power. That range is roughly 1/6000 seconds to 1/30,000 seconds. The nice thing is the strobe, if you use a Nikon extension cable, will fire at high speed. Try to keep the strobe off the camera or you will get strong reflected light from the iridescent pigments in the feathers.