July022007

Nature Photos of the Week

July 2, 2007

Feathers and Young Birds!

Natal downs are present on some birds even right at the time they hatch. These feathers are responsible for giving baby chicks and ducklings their fluffy appearance. Natal downs are typically found on well developed hatchlings that can almost immediately walk or swim independently of their parents (precocial birds).

The distinction between precocial and altricial species is particularly sharp in birds. Precocial birds, including many ground-nesting species, have offspring that are born covered with down and ready to leave the nest in a short period of time following hatching (e.g. 24 hours). This amount of time is necessitated by the fact that offspring require time for their downy coats to dry.

Additionally, most precocial chicks lack the ability to regulate their own body temperatures (thermoregulation), and they depend on the attending parent(s) to provide an outside source of heat for a short period of time. Precocial birds find their own food, sometimes with help from the parents. Examples of precocial birds include the domestic chicken, many species of ducks and geese, rails, and sandpipers.

The young of most passerine species, such as American Robins, are totally helpless and virtually naked at birth (alticial birds). It is thought that the these baby birds save energy by not producing down and are able to absorb the body heat of the parent bird more easily.

submitted by Ross Strickland

Altricial species are those whose newly hatched young are relatively immobile, have closed eyes, lack hair or down, and must be cared for by the adults. Altricial young are born helpless and require care for a comparatively long time. Among birds, these include, for example, herons, hawks, woodpeckers, owls, and most passerines.