Precocial

Precocial

In Biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. The opposite developmental strategy is called "altricial", where the young are born helpless. Extremely precocial species may be called "superprecocial". These three categories form a continuum, without distinct gaps between them. Precocial species are normally nidifugous, meaning that they leave the nest shortly after birth.

The span between precocial and altricial species is particularly broad in birds. Precocial birds, including many ground-nesting species, have offspring that are born with well-ossified skeletons, with good sight, and covered with feathers. Very precocial birds can be ready to leave the nest in a short period of time following hatching (e.g. 24 hours). Many precocial chicks are not independent in thermoregulation (the ability to regulate their own body temperatures), and they depend on the attending parent(s) to brood them with body heat for a short period of time. Precocial birds find their own food, sometimes with help or instruction from the parents. Examples of precocial birds include the domestic chicken, many species of ducks and geese, and rails and crakes. The most extreme, superprecocial birds are the megapodes, where the newly-hatched chicks dig themselves out of the nest mound without parental assistance, and fly on the first day after hatching.

Precociality is found in many other animal groups. Familiar examples of precocial mammals are most ungulates, the guinea pig, and most species of hare. This last example demonstrates that precociality is not a particularly conservative characteristic, in the evolutionary sense, since the closely related rabbit is highly altricial.

Precocial species typically have a longer gestation or incubation period than related altricial species, and smaller litters or clutches, since each offspring has to be brought to a relatively advanced (and large) state before birth or hatching.

The phenomenon of imprinting studied by Konrad Lorenz is characteristic of precocial birds.

Etymology

The word "precocial" is derived from the same root as "precocious", implying in both cases early maturity. ["Webster's New World Dictionary". David B. Guralnik, Editor in Chief. New York:Simon and Schuster, 1984.]

Phylogeny

Precociality is thought to be ancestral in birds. Thus, altricial birds tend to be found in the most derived groups. There is some evidence for precociality in Protobirds (Elzanowski, 1995.) and Troodontids (Varricchio et al. 2002).

References

Footnotes

Notations

*Starck J.M., Ricklefs R. E. Patterns of Development: The Altricial - Precocial Spectrum. In; Avian Growth and Development. Oxford University Press, New York, NY, 1998.


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Look at other dictionaries:

  • precocial — [prē kō′shəl] adj. [< ModL praecoces (< L, pl. of praecox: see PRECOCIOUS), precocial birds + AL] designating or of birds whose newly hatched young are covered with down and fully active: opposed to ALTRICIAL …   English World dictionary

  • precocial — adjective Etymology: New Latin praecoces precocial birds, from Latin, plural of praecoc , precox Date: circa 1872 capable of a high degree of independent activity from birth < ducklings are precocial > compare altricial …   New Collegiate Dictionary

  • precocial — US var. of PRAECOCIAL. * * * precocial, a. Now the usual spelling of præcocial a …   Useful english dictionary

  • precocial — 1) young showing independent activity from birth. Opposite of altricial 2) a fish that has matured quickly, or faster than the remaining fish of its age class. Usually exhibited by male fish …   Dictionary of ichthyology

  • precocial — /pri koh sheuhl/, adj. Biol. (of an animal species) active and able to move freely from birth or hatching and requiring little parental care (opposed to altricial). [1870 75; PRECOCI(OUS) + AL1] * * * …   Universalium

  • precocial — adjective hatched from the egg already covered in down and with eyes open; capable of leaving the nest within a few days …   Wiktionary

  • precocial — prɪ kəʊʃl adj. (about animals) requiring little parental care, able to move about and function almost entirely independently upon birth (Zoology) …   English contemporary dictionary

  • precocial — [prɪ kəʊʃ(ə)l] adjective Zoology relating to or denoting a bird or other animal species whose young are hatched or born in an advanced state and are able to feed themselves almost immediately. Often contrasted with altricial. Origin C19: from mod …   English new terms dictionary

  • precocial — pre·co·cial …   English syllables

  • precocial — pre•co•cial [[t]prɪˈkoʊ ʃəl[/t]] adj. dvl active and able to move freely from birth or hatching and requiring little parental care (opposed to altricial). • Etymology: 1870–75; precoci ( ous) + al I …   From formal English to slang

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