Bird Patterns of Development -- Page 1

To a great extent, the kind of care require is determined by the development pattern of the Chicks. Ornithologists separate those development patterns into two kinds: altricial and precocial.

The chicks of altricial species--which includes songbirds, woodpeckers, hummingbirds, hawks, and owls--are naked and blind when they hatch, and are too weak to do anything but open their mouths to be fed by the parents. Altricial chicks usually remain in the nest for two or more weeks, until they have developed enough plumage, strength, and coordination to fly short distances. After fledging they may remain dependent upon the parents several weeks longer for protection and feeding. You may see full sized young birds at this time begging and harassing their parents for food.

In contrast, the chicks of precocial species, such as ducks, geese, grouse, pheasants, shorebirds, and grebes, are appealing and capable birds at birth. At hatching they are covered with a thick layer of down, have well-developed legs and bills, and their eyes are open. Sandpiper and plover chicks may leave the nest within hours of hatching, and before they are one day old can run, hide, peck at insects on low vegetation. The parent or parents do not need to carry food to these chicks, which is the most-consuming job of parents of altricial chicks. .

Precocial parents need only lead the chicks to appropriate feeding habitats, keep them warm during the first days by occasional brooding, and protect them from predators This last job is especially critical. Since the chicks are moving around in open habitat, they are easily noticeable; because they are unable to fly, they are easy prey. Among shorebirds the solution is a combination of remarkable chick camouflage and energetic adult distraction displays. Baby shorebirds have special down feathers that create a finely spotted effect to break the outline of the chick, and their response to an alarm call from a parent to crouch, motionless, amid the vegetation. The parent then employs the rodent run, broken wing, or other distraction displays. The distraction displays are often so artful and insistent that the predator is drawn far away from the chick area. Afterwards, the parent circles back, giving the all-clear whistle, and gathers the brood together again. Many precocial waterfowl chicks are even better equipped to avoid predators because they can swim almost from birth.