A female hummingbird caring for her young is a busy bird -- particularly if she has two broods during the summer season. These tiny birds start life very vulnerable, so Mom is very busy ensuring they eat and stay warm. It doesn't take long for them to leave the nest.
When a hummingbird lays her eggs, she usually lays two oblong eggs, around 1/2 inch long and 1/3 inch wide, though some species may be a bit larger or smaller. Depending on the species, she may spend less than a minute or up to three hours at a time sitting on her eggs, taking breaks of less than a minute to half an hour. Generally, incubation is between 14 and 17 days, but that can be affected by weather and the species.
When the babies hatch, their eyes are closed, they have no feathers and weigh about one-third of the weight of a dime. They're about an inch long and can't regulate their body heat, so Mom takes care to nest with them for the first eight to 12 days. At about two weeks, the nestlings have developed enough temperature regulation to stay warm through the night in the nest. During this time, the chicks are fed regurgitated insects, as Mom inserts her long beak down their throats, usually one to three times an hour. Chicks leave the nest when they're ready to, usually after about three weeks; however, harsh weather conditions can extend the nesting period. Mom will help her fledglings a few days after they take off, showing them where to catch bugs and find nectar, before she chases them off to live on their own.