Altricial Birds[]
Most passerines, such as these Spotted Flycatchers, are altricial.
Altricial is a term used to describe the condition when a hatchling is underdeveloped at the time of hatching and are completely dependent on its parents. Altricial or nidicolous birds typically hatch out of small eggs in a nest built above ground. Birds that are altricial are blind, naked, and helpless when they hatch. They grow quickly, develop feathers, and usually leave the nest within 2 or 4 weeks. When young altricial birds fledge, they're called fledglings. Parent altricial birds care for their fledglings for a short time after they leave the nest until they're completely independent. New altricial fledglings often follow their parents around and beg for food. Birds such as herons, falcons, hawks, woodpeckers, owls, parrots, pigeons, cuckoos, and most passerines have altricial young.
Semi-altricial[]
Semi-altricial birds are covered with down, incapable of departing from the nest, and are fed by the parents. In species classified as semi-altricial 1, such as hawks, storks and herons, chicks hatch with their eyes open. In the category semi-altricial 2, for example, owls, hatch with the eyes closed.
Precocial Birds[]
.jpg){kind=link}
Domestic fowl chicks are precocial.
Precocial or nidifugous birds are much more developed than altricial birds when they hatch out of their eggs. Some young precocial birds can feed themselves soon after hatching, while others, like gulls and terns, have to depend on their parents for food. They're covered with down feathers, have their eyes open, and are capable of locomotion shortly after hatching. With their fluffy feathers and down, precocial chicks can usually keep themselves warm without help from their parents. They usually hatch out in relatively simple nests on the ground and stay with their parents until they can look after themselves. They grow much more slowly than altricial birds and it takes them a long time, often 2 months or more, before they're able to fly. Parents of precocial chicks spend a lot of time watching out for predators, since the small, flightless chicks are easily vulnerable to attack until they grow their remiges. Birds such as ratites, landfowl, ducks, shorebirds, cranes, gulls, geese, swans, terns and many wading shorebirds have precocial young.
Semi-precocial[]
The semi-precocial chick of a European Herring Gull.
Semi-precocial hatchlings hatch with eyes open, covered with down, and capable of leaving the nest soon after hatching (they can walk and often swim), but stay at the nest and are fed by parents. Basically precocial but nidicolous, this developmental pattern is found in the young of gulls and terns.