Hummingbirds are tiny birds known for their incredibly fast metabolism and agile flight. Their life cycle, from a minuscule egg to a fully-fledged bird, is a remarkably rapid process. This swift development allows them to grow at an astonishing pace, transforming from helpless hatchlings into independent flyers in a matter of weeks. The speed of their growth is a testament to their unique biological adaptations.
From Egg to Hatching
The journey of a baby hummingbird begins with a remarkably small egg, typically the size of a coffee bean, measuring between 0.5 and 0.8 inches in length and weighing less than half a gram. A female hummingbird usually lays two white, elliptical eggs, often a day apart.
The incubation period for hummingbird eggs is notably short, generally ranging from 11 to 18 days, though it can extend up to 21 days in cooler weather. The female hummingbird is solely responsible for incubation, sitting on the eggs almost continuously. She only leaves the nest for brief periods to feed, ensuring the consistent warmth needed for the embryos’ rapid development.
Inside the Nest Growth
Once hatched, hummingbird nestlings are altricial, meaning they are helpless, blind, and largely featherless. They weigh approximately 0.62 grams, less than a dime. Their eyes typically open around 7 to 10 days after hatching, and their beaks are initially short and stubby, gradually elongating as they grow.
Feather development is rapid; pin-like feathers begin to appear around day 7 to 10, and a full set of feathers usually develops by about three weeks old. The nestlings grow quickly. To fuel this intense growth, the mother constantly feeds them a high-protein diet of small insects and nectar. She inserts her long bill directly into their throats, feeding them frequently throughout the day.
Fledging and Beyond
The transition from nestling to fledgling happens swiftly. Baby hummingbirds are ready to fledge, or leave the nest, about 18 to 28 days after hatching. At this stage, they possess all their feathers and are capable of flight.
Upon leaving the nest, fledglings are not yet fully independent. The mother continues to feed them for about another week as they refine their flying skills and learn to forage for themselves. She teaches them how to catch insects on the wing and locate nectar sources. Within approximately one month of hatching, young hummingbirds typically become self-sufficient and reach their adult size.
Factors Affecting Development
Several factors influence a baby hummingbird’s development. A consistent and abundant food supply is important, as the mother must provide a high-protein diet of insects and nectar to support the nestlings’ rapid growth. The availability of these food sources directly impacts the nestlings’ health and development.
Environmental conditions also play a role. Extreme weather, such as high temperatures, heavy freezes, strong winds, or prolonged rain, can pose threats to nests and young birds. Nests can be damaged by wind and rain, while temperature extremes can be fatal to eggs and chicks. Predators, including snakes, lizards, jays, crows, squirrels, and domestic cats, can target nests, eggs, and vulnerable chicks, impacting survival rates. The quality of parental care, particularly the mother’s ability to protect the nest and consistently provide food, directly affects the young’s survival.