There are a lot of birds in my yard, but the most attractive of them all is the hummingbird.

I’ve been watching them for quite sometime now and what I found most stunning about them is their whimsical, fairytale-like presence, which in combination with their strong territorial tendencies renders them quite fascinating, in my opinion.
Being a territorial animal myself, I do understand the need to ferociously protect one’s turf. I personally often engage in mile long chases (chipmunk miles, mind you, are bit shorter the human ones) that are designed to forever deter intruders from entering my area, not to mention my feeding station. So, in order to do that we just run and run until one of us decides that we are in no chipmunk’s zone and it is time to let go.
But, I am not sure how does it work with hummingbirds. For few days now, I have been watching this one female who was determined to fend off any hummingbird that came close to the feeder. Each time one of the neighboring hummingbirds casually arrived at the feeder, she would launch at them with full force. But, I can never tell what happens next. After the launch, that is. Seconds after pursuit starts both birds vanish into thin air and the only palpable thing is the descending hum of their wings. Next thing you know they are gone.

Then, few seconds later the female returns to her perch and resumes her wait for another victim. How do they know where they are going. Can they see one another? Do they know which way they fly? I mean chipmunk chase is fast enough for some to even realize it happening, but even if we do not see the intruder, we can always hear his/her squealing and a fast moving upright tail. What does a hummingbird go by?