The Anna's hummingbirds that visit the garden are very territorial about the nectar we cook for them, especially when the nectar is fresh.
The hummingbirds like to perch on the highest branches of the cape honeysuckle shrub (photo above), even in light rain and guard the area where the nectar stand is. If any competition flies anywhere near the nectar, the "guard" bird swoops down from the branch and chases away the invader.
Then it returns to its perch on the shrub.
The day a fresh batch of nectar was put in the feeder, this Anna's hummingbird was very agitated when another hummingbird flew nearby to get to the feeder. This bird perched below the nectar feeder, on the lower arch of the feeder stand (and old birdcage stand we discovered when we cleared the backyard many years ago) and swayed to the left, then to the lright, repeatedly, making sure the other hummingbird didn't get close to the feeder.
Look how it is puffed up, compared to the image below, taken afterwards.
Satisfied that there was no competitors nearby, it was time to savor the delicious fresh nectar.