How Do Bald Eagles Work?

These large, intelligent North American birds weren't everyone's first choice for a United States icon. Learn more about bald eagles in this episode of BrainStuff, based on this article: https://animals.howstuffworks.com/birds/bald-eagles.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to Brainstuff, a production of iHeartRadio. Hey brain Stuff,
Lauren Vohlbaum. Here, if you're a fledgling nation selecting a
national bird, you could do a lot worse than the
bald eagle. It's got the stately profile and steely eyed gaze,
the dramatic contrast coloring, and huge wingspan, which is all

(00:25):
part of why members of Congress chose the bald eagle
to represent the United States in seventeen eighty nine. For
the article this episode is based on How Stuffworks, spoke
with Scott Cordon, wildlife curator at the Center for Wildlife
Education and the lamar Q Bald Junior Raptor Center at
Georgia Southern University. Cordon is an expert falconer and manages

(00:46):
the center's najerie, which includes two bald eagles. First off,
to be clear, these eagles don't have the bald moniker
because their heads look hairless, but rather because they're white.
Their name comes from the Middle English word bald b alde,
meaning white, but bald eagles don't develop those striking white

(01:10):
head and tail feathers until they're mature, somewhere between the
ages of four and five years old. Immature Bald eagles
are mostly dark brown in color, with mottled brown and
white wings. They also don't fully develop the bright golden
yellow coloration on their beaks and feet until they're mature.
When they reach full size, bald eagles are big, with

(01:31):
the female eagles growing a bit larger than males. Overall,
they can weigh around nine to fourteen pounds that's about
four to six and a half kilos, with a wingspan
of around five and a half to seven feet or
about one point six two one point two meters. Only
a few other North American birds, like the golden eagle
and the California condor, are as large or larger. Bald

(01:53):
eagles are in the sea eagle family, meaning they live
near rivers and coasts and hunt mostly fish and white fowl,
but they're considered opportunistic carnivores, which means that they usually
eat whatever is available, including other small game like rabbits, squirrels,
or rodents, plus deadfish that have washed up on shore,
or even stolen prey from other birds such as osprey's.

(02:17):
The scientific name for this type of food snatching behavior
is klepto parasitism, but it's most common among the immature birds.
Once mature, bald eagles can be formidable hunters. When a
bald eagle swoops down to catch its prey, it uses
its razor sharp talons to snatch the unlucky animal it's
decided to make a meal out of. They'll roam a

(02:39):
pretty wide hunting territory about twenty five miles across some
forty kilometers. But for all that, your average bald eagle
can easily live off of a couple of adult rats
per day. Corton said, most birds don't eat every day
because they'll catch something that's large enough to sustain them
for a couple of days. Instead, they might feed off
of something large and fill their a part of their

(03:01):
digestive system where they temporarily store food that can sustain
them for two or three days, sometimes even longer. A
Bald eagles are the only sea eagles endemic to North America,
and they really have the territory covered. The bald eagles
range stretches from southern Alaska to northern Mexico and from
coast to coast. Due to their distinctive plumage, they are

(03:23):
almost impossible to mistake with other birds, even other large eagles.
When you see that white head soaring above the trees,
it's a bald eagle for sure. These birds can be
very social under the right circumstances. When food is plentiful
and it's not nesting season, a few to a few
hundred may roost together and have been observed engaging in

(03:44):
play behavior even as adults. They also mat for life,
though if one of a pair dies, the surviving birds
sometimes finds a new mate and they take nesting seriously.
Mates built nests called aries together, which takes around one
to three months. They also trade parental duties, with both
birds incubating the eggs for the five weeks or so
that it takes for them to hatch, because it takes

(04:07):
the hatchlings ten to twelve weeks to grow to the
point that they fledge, that is, take their first flight.
Eagles only lay one clutch or a group of eggs
per year. Cordon said. If their eggs or their young
are destroyed early enough in the season, they will lay
another clutch to try to reproduce again. In fact, that's
part of how they got the bald eagle population back up.

(04:30):
They would remove eagle eggs from the nest early in
the season and the adult eagle would lay another set
of eggs. It's called a double clutch. Due to these efforts,
the bald eagle was removed from the federal endangered species
list in two thousand and seven and is off every
state endangered species list too, though it's still protected by
several laws to prevent the population from dipping again. But

(04:53):
back to those nests. A bald eagles have the largest
nest of any bird species in North America. Their average
nest size is up to five feet across and four
feet deep that's about one point five by one point
two meters. The biggest arion record was built by pair
bald eagles in Saint Petersburg, Florida. It measured twenty feet
by nine feet that's about six by three meters, and

(05:15):
weighed two tons. A Cordon explained eagles only live in
their nest during the mating season, incubation, and while they're
raising the fledglings. Once they learn to fly and everyone
is out, they don't live in the nest. The birds
will return to the same nest year after year if possible,
but will leave if the tree's built in can't sustain it.

(05:38):
They're also pretty smart. A Courton said, they tend to
never forget anything, and they hold grudges. If you're training
an eagle and you make a mistake, that can either
ruin the training you've done or set you back several months.
But it's important to note that the bald eagle wasn't
the only bird in the running for a national symbol.
A founding father, Benjamin Franklin and favored the turkey as

(06:01):
the national bird, calling it more respectable and with all
a true original native of America. Part of Franklin's beef
was that the bald eagle is a scavenger. Corton said,
of all the birds of prey other than the vultures,
bald eagles will most readily go to a dead animal
on the side of the road, where other birds of
prey will only carry in if they're starving. Nevertheless, the

(06:25):
bald eagle was chosen as a symbol of strength, courage,
and freedom, and despite Franklin's comments, the bald eagle is
indigenous only to North America. Today's episode is based on
the article Bald Eagle, size, diet and History is a
National Icon on HowStuffWorks dot com, written by Patty Rasmusen

(06:47):
Brain Stuff is production of by Heart Radio in partnership
with HowStuffWorks dot Com and is produced by Tyler Klang.
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