Hummers are fierce. How do I know? Well, we have had a group of 7 frequenting two feeders for years with usually one obnoxious male guarding the stash along with one dominant female as silent partner. As often stated, one never grows tired of watching incredible aerial acrobatics and threat posturing to the nth degree in the birds' endless pursuit to get access to the all important sugar water when insects and flower nectar become increasingly scarce.
If you want to know what makes hummingbirds tick, it’s best to avoid most poetry about them.
Whither? Probably off to have a bloodcurdling fight, that’s whither.
Ferocity personified indeed. :)