As young hummingbirds grow up in the nest, they will strengthen their wings by firmly grasping hold of their cottonlike nest or a branch very nearby, and power up their little motor. They start very young, and by the time they are ready to leave the nest they have built up an endurance to fly or at least do short bursts to another nearby branch. They soon have the ability to fly like most adult hummingbirds, but lack the special abilities to fly and feed from awkward flowers. It really doesn't take long once they've been chased or engaged in battles to build up the muscles needed for greater endurance. But within the first few days away from the nest they still lack the strength in those wing muscles to perform like an adult. They will gradually increase their feeding time, and/or learn which food sources require less energy to feed.
This young Ruby-throat solved the problem after it tired out and perched on a Delphinium branch. It shuffled along the branch and just poked around in the flowers, no matter how awkwardly it had to contort it's body. Young hummingbirds can often times be identified by this behavior. They will perch in flowers and regain energy, even if just for a few seconds. They may be little but they're not lazy. It's just to regain strength, and then it's back to business. Adults will refuse awkward flowers unless they're the only ones available.
Young Male Ruby-throat hummingbird. N.E. of Edmonton, Alberta, Canada. August 2, 2018