Biology Reference
In-Depth Information
startled by a predator, young of these species tend to remain in the nest until they are
strong fliers.
All About Eggs
Q How many eggs do birds lay?
A
Thisdependsonthespecies. Somespecies, suchasalbatrosses andsomepenguins,lay
just one egg each time they attempt to raise young. Despite their difference in body size,
Ruby-throated Hummingbirds and Common Loons lay two. Many songbirds lay four or
five eggs, but chickadees and House Wrens usually lay six to nine and the even tinier
kingletsmaylayevenmore!Ducksandgrousecanlayadozenormoreinasingleclutch.
If something destroys the nest early in the season, most birds can start over, but if it's too
late, they give up for the year.
Many birds are
indeterminate layers
, meaning if their eggs are removed one by one,
they'll continue laying more for a long time. People take advantage of this with domestic
poultry, but indeterminate laying is also present in wild birds. In one experiment, an egg
was removed each day from a Northern Flicker nest (a species that normally lays 6 to 9
eggs in a clutch), and the female produced a total of 71 eggs in 73 days.
Q How long does it take for eggs to hatch?
A
Itdependsonthespecies.Smallsongbirdeggscanhatchinjust11days,Ruby-throated
Hummingbirds in 12 to 14 days, Common Loons and many ducks in about 28 days, Bald
Eagles in about 35 days, and Emperor Penguins in about 65 days.
On average, clutch sizes are smaller in the tropics, where adults are long-lived, than in
the temperate zone, where birds live fast and die young.
