Hummingbirds primarily eat flower nectar, tree sap, insects and pollen. The hummingbird's fast breathing rate, fast heartbeat and high body temperature require that they eat often. They also require an enormous amount of food each day.
Brightly–colored flowers that are tubular hold the most nectar, and are particularly attractive to hummingbirds. These include perennials such as bee balms, columbines, daylilies, and lupines; biennials such as foxgloves and hollyhocks; and many annuals, including cleomes, impatiens, and petunias.
If you are patient, they should eventually start feeding from the one you're holding. When you have good hummingbird traffic one day, remove your other feeders. Next, place a small feeder filled with sugar water in the palm of your hand (Abigail used an old milk jug lid).
When hummingbirds sleep and are in the Torpor state, they have been known to hang upside-down. If you find a hummingbird that is hanging upside-down and they appear to be dead, it is actually more likely that they are just asleep. ... The hummingbirds will eat 25% of their daily intake as soon as they recover from torpor.