Luckily with all of the time he spends outside, Ranger has not proven to be too adept at catching birds. (Yes, I'm knocking on wood - at least metaphorically - as I say that!) Animal-snob that I guess I am, I'm not too worried about the hispid cotton rat population that seems to provide him with the most frequent victims. It'll be another matter altogether if he starts getting Harris sparrows, Carolina wrens or goldfinch.
Anyway, I got quite a laugh last week when he suddenly discovered a fox squirrel that comes in occasionally to bulk up at the feeders. As I stood at the kitchen sink washing dishes, the first thing I noticed was a rusty blur streaking along the ground and up a tree. Then a black blur followed close behind it. When the action paused, the squirrel was high up in the branches of the green ash, chattering and flicking its tail vigorously, not letting its eyes leave Ranger. Ranger actually disappointed me - he climbed up in the tree and seemed to study all the angles for several minutes, but abandoned the chase that day after barely getting 1/3 of the way to his quarry.
By the next day, he was more determined, however, and worked his way at least halfway up the tree before deciding to go after easier prey. (Maybe the grayer day just had him more inclined to chase away his boredom.)
I'm quite sure that the squirrel can balance on far smaller branches than Ranger can, but it's going to be interesting to see how far out a limb Ranger is willing to go!