Biology Reference
In-Depth Information
identifying them to observing their behavior. But now that I'm paying attention, I'm
wondering why my chickadees come in flocks the way my goldfinches do, but the
chickadees never sit side by side and eat together the way the finches do. Why is
that?
A
I agree that watching bird behavior is fascinating! Every species has its own set of be-
haviors that make it successful in its own habitat.
Goldfinches are one of the rare species that eat almost entirely seeds, even feeding
their nestlings mostly a seed diet rather than the insects that most growing young song-
birds need for protein. Goldfinches and their relatives tend to eat food items that are
“patchy” — abundant in a few spots at a time while not at all available in other places.
By spending time in a flock and wandering widely, they have plenty of opportunities to
discover new patches of appropriate food. But these food supplies can be depleted within
a short window of time, either as goldfinches or other animals eat them or as the plant
sheds them. This is factored into the game plan of nomadic flocking birds: when the food
is used up, they move on. So whether in the wild or at your feeders, normal goldfinch
behavior is to feed together.
Chickadees aren't nomadic — a winter flock stays within an area of about 25 acres
(10 ha) for the entire season. Chickadee flocks benefit from many eyes to spot predators
andnewfoodresources,butindividualbirdshideandstoreseedsandotheritemsforlater
feeding, so individuals prefer to keep more distance between themselves and other flock
members. Usually chickadees space themselves from about 3 to 30 feet (1-10 m) apart,
whereas the distance between goldfinches at a feeder can be measured in inches.
