From Sciencenewsforkids.com
Some birds are masters of crime. These
sneaky
species steal food from other birds—and
get away with it.
A
diverse collection of birds
is guilty of such thievery, and scientists have
long wondered what these families of birds have in common.
A new study suggests that big body size does not predict
bullying behavior. Instead, among other traits, it is the
size of the birds' brains that matters most.
Food
theft is also called kleptoparasitism, and about 2 percent
of the world's birds do it. That's 197 out of 9,672 known
bird species that have been seen swiping food from other
bird species.
Certain families of birds, including falcons, eagles, and
pelicans, are especially
prone to stealing.
Some songbirds, on the other hand, are less likely to
steal.
To
learn more about what makes some birds tend toward a life
of crime, scientists from the University of Québec at
Montréal analyzed 856 published reports of
theft by
one bird from another.
Researcher Julie Morand-Ferron, a member of the study
team, says she started the project after watching birds in
Barbados sneak dry dog food out of unattended bowls. The
birds, called Carib grackles, then snatched pellets from
each other.
For
her study, Morand-Ferron considered only birds that steal
from other species of birds (rather than from dogs,
people, or the thief's own species). She read about some
dramatic examples of thievery, including birds that
grabbed
food from others in midair and high-speed chases during
which birds zigged
and zagged through the sky. She learned that
members of some species harass other birds until they spit
up food that they'd swallowed.
The
team found some patterns among the behaviors of the birds
they studied. For one thing, bird families that often
steal tend to live in open environments such as ocean
shores. There, they can easily see the targets of their
attacks.
Kleptoparasitic families also tend to eat fish, mice, and
other vertebrates instead of just insects. These meatier
meals are hard to catch, and they deliver lots of valuable
calories, so they are
tempting to steal.
Finally, kleptoparasitic birds tend to have big brains in
relation to their bodies. That may seem surprising, since
human bullies are often thought to be stronger in size
than in smarts.
But
for birds, stealing isn't about brute strength. It takes a
clever bird to get food out of another hungry bird's
claws, especially if that bird is bigger than you are. In
other words, birds that steal might deserve some respect.
"There's this stigma attached to individuals who steal
things to make a living: that they can't catch fish or
forage on their own," says David Shealer of Loras College
in Dubuque, Iowa.
But
Shealer has studied birds called roseate terns. And the
terns that steal, he says, are "far and away the best
parents."
But
don't take this as advice to start swiping cookies from
your classmates' lunches. These are birds we're talking
about!—Emily Sohn