1: Tree for Two
usually lay two eggs. One scientist studied 77 Ruby-throated Hummingbird
nests. He found that 66 nests had two eggs, 10 nests held only one
egg, and one nest had three eggs.
Why do you think hummingbirds almost always lay two eggs? (Answer
egg is not the best number for hummingbird nests. If anything
happens to one baby or the egg doesn't hatch, all the work and
energy the mother put into building the nest and incubating will
be lost. But more than two eggs take too much energy from the
mother. She would have to use more body heat to warm the eggs.
She'd need so much food to feed three babies that she might grow
too weak. If weather conditions were great and food abundant,
a nest of three babies could survive — but it's
a very big risk.