(Describer) In an animation, leaves fall.
[crickets chirping]
(female narrator)
Fall is the time
for migration.
Along with ducks, geese,
and the typical snowbird,
there's another group
of feathered friends
preparing for
their yearly trip south,
but you won't see these
in your typical flying V.
Raptors migrate south
during the winter months
when their yummy morsels
are scarce,
but being a raptor,
they do it slightly differently
than most birds,
and here's how.
Seasonal Science
brings you "Raptor Migration."
(Describer) A raptor is a bird.
Step one: Find a flyway.
So, forget the flying V.
If you're a raptor,
you want to find a flyway--
a route along a mountain
or river or a coast
that creates the right
conditions for soaring.
Updrafts or thermals
let raptors coast along
without using much energy.
Each raptor species
has a different timetable
and destination,
and many use
different flyways.
Step two:
Watch the weather.
Flapping is super costly
physiologically,
so the weather is key
in aiding the journey.
One to three days
after a September cold front,
when the conditions are right
for updrafts and thermals,
is the ideal time
for most raptors
to board the solar train
and book it down south,
especially if you're
an obligate soaring migrant
like the broad-winged hawk.
If a raptor misses
this small solar window,
or there's
a poorly timed hurricane
or drought or heat wave,
the migration
could be thrown off,
and an entire population
can suffer.
Step three: Make frenemies.
Raptors are solitary
and competitive normally,
and most raptors,
like eagles and harriers,
stick to these solitary ways
and take a leisurely pace south,
hunting as they go.
But during migration season,
raptors like
the broad-winged hawks
forego all that
competition nonsense
and coalesce into large groups
called "kettles"--
hundreds, sometimes thousands
of broad-winged hawks
on their way upwards
and down south.
Young birds find older mentors,
and the more birds
there are,
the easier it is
to find a thermal.
And step four:
Settle in for the duration.
Once they've settled
in their southern locations
for the winter,
they do what raptors do.
They sit back, relax,
shred small mammals,
and prepare to do it all again
when they head back north
in the spring.
(Describer) Titles: Seasonal Science by Melissa Salpiera.
Science Advisor: Keith L. Bildstein, Hawk Mountain Sanctuary.
Accessibility provided by the US Department of Education.
Accessibility provided by the
U.S. Department of Education.
