Ruby-throats are intensely inquisitive and easily attracted to feeders. Hummingbirds quickly become accustomed to human presence and will swoop down to investigate red articles of clothing, possibly as potential food sources.
The bird that claims a feeder as its territory may spend much of the day perched nearby, guarding the food source against intruders. Males in particular typically display aggressive territoriality toward rival hummers, other birds, and even insects such as bees, butterflies and moths.
Aggressive and territorial.
That is...until he sees a pretty lady.
And they're not nearly as aggressive or territorial.
They have friends and share nicely.
Hummingbirds have no sense of smell.