Altricial

Altricial refers to a developmental strategy in certain animals, particularly birds and some mammals, where the offspring are born or hatched in an undeveloped state and require extensive care and feeding by the parents. This is in contrast to precocial species, whose young are relatively mature and mobile from the moment of birth or hatching. The term "altricial" is derived from the Latin word "alere," meaning "to nurse, to rear, or to nourish," which reflects the high level of parental investment required in raising altricial offspring.

Characteristics

Altricial young are typically born with their eyes closed, lacking feathers or fur, and are incapable of leaving the nest or den. They are highly dependent on their parents for warmth, protection, and nourishment. This state of helplessness at birth or hatching extends the period during which the offspring remain in the nest or den, receiving care from their parents.

Examples

Among birds, species such as owls, hawks, sparrows, and most songbirds are altricial. They hatch from their eggs in a very immature state, requiring weeks of parental care before they are ready to fledge (leave the nest). In mammals, examples of altricial species include rodents, rabbits, dogs, and cats. These species give birth to relatively undeveloped young, which stay in a den or similar protected environment until they are capable of some degree of independent activity.

Evolutionary Significance

The altricial strategy allows for the birth or hatching of offspring in a less developed state, which can reduce the gestation or incubation period and potentially allow for a larger number of offspring per breeding attempt. However, it requires a significant investment of time and resources from the parents to ensure the survival of their young. This strategy can be advantageous in environments where resources are abundant and the risks of predation are lower, as it allows parents to produce more genetically diverse offspring over time.

Comparison with Precocial

The opposite developmental strategy is seen in precocial species, where offspring are born or hatched in a more developed state, with their eyes open and capable of moving around almost immediately. Precocial young are less dependent on their parents for survival, which can be advantageous in environments where the risks of predation are high or where parents are less able to invest time and resources in their care.

Implications for Conservation

Understanding whether a species is altricial or precocial can have important implications for its conservation. Altricial species may be more vulnerable to environmental changes that affect their nesting habitats or the availability of food resources, as their young require more prolonged care. Conservation efforts for these species may need to focus on protecting nesting sites and ensuring that parents have access to sufficient food to rear their offspring.

See Also

• Life history theory
• Parental investment
• R/K selection theory