Logically speaking, if a hummingbird drinks too much nectar, it will be temporarily overweight and less able or unable to fly to escape danger. However if the same hummingbird doesn't drink enough nectar, it will suffer the same problem of not being able to flee danger, but for the different reason of it wouldn't have enough energy to do so. Hummingbirds are incredibly small, so I would assume they would have the most problem with this issue due to the fact it would have very little margin for error. I am not sure how much that margin is though or the marginal percent of body weight, so I'll ask that question too.
What mechanisms do (humming)birds have to regulate and control their body weight and their energy needs and scouting and timing the acquisition of their next potential food source? What is their margin for error and how do they meet it and how did they meet it in the past?
EDIT: I want a more concise question, so hopefully this is answerable:
Alternatively and optionally, Can you describe to me a general day in the life of a Hummingbird? I want to know what good decisions it makes over the course of its "perfectly average" day to survive. Such things as what it does to avoid dangers, and how it finds its time to eat and how much it eats and at what intervals, and what it does with the rest of its time?