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Desert Diary


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Many a proud parent has said, "My child is really precocious!", meaning very advanced for her age. Precocial, a similar word with much the same meaning, is used for animals by naturalists, along with its opposite, altricial.

Here in the Chihuahuan Desert, we have a number of animals demonstrating both. Our Black-tailed Jackrabbit, for example, is precocial. That is, born in an advanced state, with fur, open eyes, and the ability to move around shortly after birth. On the other hand, its altricial relative, the Desert Cottontail, has young who are born virtually naked, with eyes and ears sealed and a relatively long, helpless time in the nest.

The bird world is as productive of examples. Precocial quail are covered with downy feathers at hatching, and within hours are scrambling around, pecking at potential food items. Contrast this with a Desert Sparrow, born helpless and ugly, utterly dependent on Mom and Dad for days.

Is one better than the other? No—just different ways to get to the same end—survival and reproduction of the next generation.
pen and ink

Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.

photo of ducklings

Mallard hen and ducklings. The ducklings are precocial and ready to take to the water shortly after hatching. Photograph by Marguerite Gregory. © 1999, California Academy of Sciences.



Vaughan, T. E., J. M. Ryan, and N. J. Czaplewski. 2000. Mammalogy, 4th ed. Saunders College Publishing, Philadelphia.

Welty, J. C. 1982. The Life of Birds. Saunders College Publishing, 3rd ed., Philadelphia, 754 pp.

Web Resources

Messenger Woods. Descriptions and photographs of altricial and precocial birds in the theme of rescuing baby birds.