It’s in Our Nature: Precocial or altricial birds

All birds hatch from eggs warmed by one or both of the parents. However, after hatching, birds’ developmental processes may be drastically different.

Precocial birds are those species whose young are quite developed after hatching and shortly after that are mobile enough to leave the nest area with parental care continuing.

The simplest example of precocial birds would be domesticated chickens. The chicks soon after hatching are tiny downy miniatures of the adult birds. In the wild, examples of precocial birds are: ducks, geese, grouse, turkeys, and killdeer.

Precocial birds with few exceptions have one clutch with often 10 or more eggs. Even though the female bird takes excellent care of her wandering brood, the young are easy prey for weasels, hawks or fox.

The aquatic precocial young (ducks, etc.) are vulnerable to large fish, snapping turtles, and hawks as well.

If a grouse has a dozen eggs that hatch, you could probably at best get to see only three or four young make it until their first autumn. The downy young face too many hurdles.

Altricial birds incubate their eggs which results in hatchlings nearly featherless and unable to move about at all.

Altricial young are essentially helpless until about three weeks after hatching when they eventually grow the body and flight feathers.

The young are fed in the nest and for about the first week are brooded almost constantly for retaining warmth.

Altricial birds generally have two nests each summer containing about four to six eggs each.

They do have fewer eggs than precocial birds but they offer the young better protection in the nest.

Altricial species include: robins, bluebirds, sparrows, wrens, blue jays, eagles and warblers.

Altricial birds somewhat mimic mammals in offering “doting” care to their growing offspring.

Heavy rains or sudden summer downpours often take their toll on precocial young. When we experience very wet May or June conditions, biologists have noted that grouse and turkey reproduction suffers.

The young precocial birds with limited feather coverings suffer from the elements. This type of weather condition is detrimental to altricial birds too; however, the females seldom leave the young untended in the nest. She is able to shelter the young much easier there.

In an earlier column I spoke of bird’s poor sense of smell. A bluebird or owl nest can be monitored and the young can be taken from the nest, banded, and returned with no ill effects. However, it is important to know that if you disturb an altricial bird nest and cause the young to “jump” from the nest too early, they too are still poorly feathered and usually still cannot fly. Their likelihood of surviving is greatly reduced so always be careful as the young mature.

Keep your eyes and ears open and enjoy what nature has to offer us. …

Test your outdoor knowledge:

Which of these does not migrate? A. Monarch Butterfly B. Blue Jay C. Red tailed hawk D. Ruffed Grouse

Last Week’s nature trivia: Unfortunately for bluebird lovers, a male house wren will sometimes enter other cavity nesting birds’ nests and puncture the eggs. They eat “tons” of insects but have this “bad” trait.

Contact Barry Reed at breed71@gmail.com.