First! Whooping Crane Pecking Order
If you are in a family
with siblings, you might feel like a bigger or older sibling has more
"power" or "rights" than those who are younger or
weaker. That's how it is for Whooping cranes, but did you know that most
wild Whooping cranes don't grow up with brothers or sisters? Wild Whooping
cranes almost always lay two eggs, but only about 60 percent hatch. Babies
face so many dangers in the wild that over one-fourth of the hatchlings
die in their first month of life, especially during the first two weeks.
1.5 percent of wild Whooping crane nests have three eggs (none have more
than that!) and all in all, only about 8 percent of nests produce two
both survive to reach the wintering grounds.
When two baby cranes in a nest DO survive, they can't waste time bickering,
especially in years when food is scarce. Fortunately, they don't usually
have to. The smaller chick (the one who hatched out one or two days after
the bigger one) can see that its sibling is stronger and bigger. It
keeps out of the way! If the smaller chick isn't careful, the bigger
one may grab it by the back of the neck, peck at it, or chase it. But
littler chick quickly figures out that it's best to simply avoid
its big sister or brother. The bigger chick is usually first to be fed
and cared for, but as long as there is enough food to support both babies,
they both have a good chance of surviving.
Big Happy Family: Cohorts and Pecking
baby cranes that were costume-raised in captivity to start forming the
Eastern flock must deal with something that wild Whooping
cranes never do: a whole group of other baby cranes, all in
the same "family." But since these birds aren't necessarily
related at all, they're called a cohort. There's plenty of food for all of them, but they still
instinctively need to sort out who's top dog—or rather,
Scientists have been raising Whooping cranes in captivity
for many years now. They have learned that when they raise a cohort,
birds eventually fall into a linear hierarchy. This means that
Crane A can "boss around" all the other cranes. Crane B can
boss around all the cranes except Crane A. Crane C can boss around all
except A and B, and so on. Other birds that have this kind of linear
include barnyard chickens and chickadees. Sometimes a whole group of
baby chickens will gang up on the bird at the bottom of the hierarchy,
even peck it to death. Chickens were the first birds observed developing
a linear dominance hierarchy, so we often call this arrangement a pecking
order. Chickadees also have a dominance hierarchy, but they work it
out without hurting each other.
Young cranes sometimes fight to figure out their dominance hierarchy. But
as soon as everyone knows exactly where they fit in, they can settle their
disputes in a surprisingly peaceful way. This is because the
dominant bird always wins whenever
two birds both want the same morsel of food, or the same particular
Socialization: Helping Cranes to Get Along
A pair of wild crane siblings are usually two days apart in age, and
because they are different sizes it's easy for them to figure out which
dominant without much fighting. Crane chicks in a captive-bred cohort
can be closer in size than sibling wild cranes. The tiniest one might
have a few days or a week of being fed alone before it meets other birds
in the cohort. When the cranes finally meet one another, it can take
while before they figure out their dominance hierarchy.
at Operation Migration want their crane chicks to work out their pecking
order without too much actual pecking. They call their process socialization.
The work on socializing crane chicks starts at the Patuxent Wildlife Research
Center when the cranes are still tiny. The process is off to a good start
by the time the young cranes are delivered to what will be their summer
home and future breeding grounds at Necedah National Wildlife Refuge in
Wisconsin. Aviculturist Kelly Maguire worked with the young cranes being
trained to follow the ultralight
on their first migration. Kelly described the very first chicks for the
project in 2001:
chicks first arrived at Necedah National Wildlife Refuge, it was
for me to see an obvious hierarchy. But within weeks, both cohorts
began showing a definite and consistent one. Hierarchy can change,
of it is reinforced during exercise. When the chicks get out of the
pen, before the ultralight takes off, they are jumping and flapping
to burn energy—but you will also see some dominate and submissive
If a lower-ranking chick gets a bit too rowdy, a "higher"
chick may grab the back of its neck, or mildly chase the submissive
one just to keep it in line. We see very little intense aggression
at this point, which seems to mean that the main structure of
the hierarchy has been established.
Order With the Ultralight
As the hierarchy works out among the birds in each cohort, and between
the two cohorts, the birds will find their "place in line" for
following the ultralight. This is a very important process. Once the
is complete, the birds won't have to argue or fight about where they
fly. When 10 or 20 cranes are flying in formation, two bickering birds
disrupt the whole line. When they all stay in proper formation,
each bird can take advantage of the air currents of the ultralight and
the birds in front of them, to make flying as easy as possible.
along helps everyone!
a paragraph explaining why it's important for the trainers and ultralight
pilots to thoroughly understand and work with the cranes' dominance
how you think having a "pecking order" order might help a
species survive. Do you think it holds true for humans (who have broader
- Play the
Pecking Order Simulation
- We humans
have many things in common with animals, including an urge to fit into
a social hierarchy. Discuss how school classes are "cohorts"
too, with a large number of students all close to the same age.Think
about the way kids in a class sort themselves out socially. How is their
"pecking order" similar to that of a whooping crane cohort?
How is it different? Write your thoughts in your journal, or discuss
as a class.
Science Education Standards
- An organism's
behavior patterns are related to the nature of that organism's environment,
including the kinds and number of other organisms present.
- An organism's
behavior evolves through adaptation to its environment. How a species
moves, obtains food, reproduces, and responds to danger are based in
the species' evolutionary history.