Altrical

Altrical, also spelled altricial, is an adjective used in biology to describe a developmental pattern in which offspring are born or hatched in an underdeveloped state and depend on parental care for feeding, warmth, and protection. Altricial young are typically helpless at birth: they may be blind, deaf, featherless or fur-less, and unable to locomote. Postnatal growth and sensory development occur largely under parental provisioning rather than independently.

The term derives from Latin alere, to nourish, via the agent noun form altrix that denotes the nourisher, and entered English scientific usage in the 19th century.

It contrasts with precocial development, where offspring are relatively mature at birth, able to move and feed themselves soon after birth or hatch. The altricial/precocial dichotomy is partly a life-history strategy related to parental investment and environmental conditions.

In birds, most passerines (songbirds) are altricial, whereas many waterfowl and shorebirds are precocial. In mammals, humans, mice, cats, dogs, and bears have altricial young; ungulates such as deer, cattle, and horses typically have precocial neonates. The degree of altriciality can influence parental behavior, nest structure, and the tempo of postnatal development.

Ecologically, altricial species often rely on extended parental care and may experience strong selection for social or cooperative behaviors, nest protection, and rapid postnatal brain and sensory development. This developmental pattern reflects broader trade-offs between parental investment, offspring survival, and ecological context.