Recently, we got a phone call from some bird scientists up in rural Alaska.
They had started working with students from the local village school to learn from each
other about the area and its amazing birds.
The students had a big idea: they wanted to make a series of videos so they could share
this knowledge with other village schools in Alaska.
And then they had an even bigger idea – what if they could share what they had learned
about birds and migration with, well, everyone?
That’s when we were called in.
So we got on a big plane and then on a way smaller plane.
And then after that, we got in a car.
And when the car got stuck in the snow, we got in an ATV.
And finally, we reached the village and the school.
That's when we got to meet the coolest, most inspiring group of students that we have ever
had the privilege of working with.
And after a lot of time spent talking and researching and drawing, we came up with the
videos you’re about to watch.
Enjoy!
This bird has a superpower most animals don’t have: it can fly.
And the reason birds can fly is because every part of their body is optimized for an airborne
life.
Birds would never get off the ground without their wings.
Bird wings are basically modified arms geared toward flying.
This is what a bird wing looks like from the side – see how it is curved?
When this shape moves through air, that curve catches air and redirects it downward, creating
a force called lift.
To keep the wing moving through the air, the bird has to flap it, generating a force called
thrust.
And as long as enough air is moving across the bird’s wing, that wing will soar.
But flap as much as they like, birds would not get very far without feathers.
Each feather has a central vein with little hair-like barbs to either side that interlock
like little zippers, which make the feather act like a little kite.
Feathers are made of keratin, which is the same stuff your fingernails are made of.
Keratin is great for feather-making, because it is both strong and light.
All of the feathers of a wing work together to give the wing as much surface area as possible
in order to catch the most air.
In order to keep air flowing across those feathered wings, birds need really strong
muscles, and even those muscles still need a little help.
That’s why a bird’s wing-flapping muscles are anchored to a strong bone called the keel
bone, which makes it easier for those muscles to keep flapping the wings.
Because flying takes more energy than running, birds have to take in a lot of oxygen to keep
from getting out of breath.
This means that birds have really efficient – and kinda weird – respiratory systems.
They don’t just have two lungs like we do – they also have air sacs tucked away in
their bodies to hold extra air.
Birds also have a one-way respiratory system – the air takes a linear path from the air
sacs to the lungs and back out.
In this way, air travels through a bird’s body the way blood travels through your arteries.
Speaking of arteries, birds also have really big hearts to pump blood to their energy-hungry
muscles, and they have big brains because flying requires smarts – I mean, they have
to be quick thinkers to avoid flying into trees.
But there is a tradeoff – for some parts to become heavier, others had to become lighter.
For example, birds lost many unneeded bones, like fingers, and even gave up their teeth
and jaws, opting instead for lighter beaks.
Birds don’t even bother with a bladder – in other words, birds can’t even hold their
pee because it might weigh them down too much.
This seems like a lot of trouble to go to just to be able to fly.
But flying lets birds forage for food in ways that other animals can’t and it allows them
to build their homes in places that hungry predators have a hard time getting to.
Not to mention birds can travel all over the world – not even oceans get in their way.
Flying requires lots of adaptations, and lots of sacrifices – but if you ask a bird, the
best way to get around is to get off the ground.
Being able to fly means that birds can move around from place to place pretty easily.
Almost half of bird species use their wings to migrate – which means that they travel
to a different place when the seasons change.
Some of them, like the waxwing, only migrate a few hundred miles, while the Arctic Tern
has the longest migration in the world, flying from the farthest reaches of the north to
the farthest reaches of the south and back every single year.
A bar-tailed godwit spends its summers in Alaska, where it happily probes for berries,
beetles, and worms with its narrow beak.
But when summer’s bounty ends, most of that food goes away, and the godwits fly to warmer
climates where food is more abundant.
But they can’t stay there forever, either.
Many of these southern spots are crowded with birds – migrants and residents alike.
So the godwits take to the wing again, flying back north in the spring to breed and take
advantage of all the food spring brings up north.
Migrations, especially long ones, can be exhausting journeys; flying across land – or the open
ocean – is risky.
Many times, there isn’t much for migrants to eat along the way, so they take care to
pack for their journeys.
And by pack, I mean, pack on the fat.
When the bar-tailed Godwit leaves Alaska for New Zealand, nearly 50% of its mass is body
fat to fuel the journey.
Many birds also migrate at night – when most would-be predators are sleeping.
Some that fly during the day avoid predators by flying in huge flocks so more eyes can
scan the horizon for threats.
Flying in flocks can have an added bonus: certain formations can reduce wind resistance,
which means that each individual bird can spend less energy on the wing.
Birds are incredible navigators that can travel half the world to find the same patch of forest
or ponds every single year.
Many birds learn their migration routes from older, more experienced birds while others
make their migrations alone following maps encoded in their genes.
They track their positions using the sun, stars, and even landmarks like rivers.
But when all of these things fail, some birds can navigate by sensing the Earth’s magnetic
field, although scientists aren’t completely sure how they manage to do it.
But birds can’t control everything.
Hurricanes and other storms make flying over the ocean perilous, while wildfires and floods
can destroy stopover habitat.
Humans pose a risk to migrants, too.
Light pollution, tall buildings, and even fishing nets are all dangers that birds face
on their journeys.
And as the climate continues to change and landscapes continue to shift, birds have had
to change their migration strategies in response.
Some are starting their migrations earlier, while others are shrinking their bodies and
lengthening their wings to deal with leaner, more stressful flights.
Thanks to skills they’ve honed over the millennia, migrating birds are adjusting to
the new world.
They might be flying into the unknown, but they aren’t totally winging it.
Humans have long noticed that birds have a tendency to disappear – at least for part
of the year.
At first, they had no idea where the birds went off to, but that didn’t stop them from
making some pretty creative guesses.
The Greek philosopher Aristotle suggested that Redstarts - which spend Summers in Greece,
annually morphed into Robins, which only spend winters in Greece.
While later, a predominant theory held that some birds hibernate on the bottoms of lakes.
And people as far back as the roman empire assumed the masses of geese that arrived every
year were hatching out of… barnacles?!.
We now know that they were all wrong – these ideas persisted because, for most people,
the idea that some birds spend half the year halfway around the world would have sounded
even more absurd.
One of the first hints that birds spend time abroad came in the form of an accidental message
from an African hunter in 1822, when a stork arrived – alive – in Europe with that
hunter’s spear sticking through its neck.
Fast-forward eighty years, to around 1900, when people began purposefully sending birds
away with their own messages, thanks to a Danish teacher’s technique of attaching
marked aluminum rings to birds’ legs and then re-releasing them.
Each recapture or sighting of a banded bird put a dot on the map, and soon, long-distance
migrations were confirmed when a white stork that had been banded in Hungary was found
dead in South Africa.
But banding can only tell researchers about single points along a bird’s migratory path
– not what happens BETWEEN those points.
We didn’t get our first glimpse of the routes birds took until the 1940s, when it turned
out that radar, which had been developed to track both airplanes and rain, was also great
for tracking masses of birds.
Radar allowed us to see the size of migratory flocks moving en masse under the cover of
night for the first time, but we weren't able to get individual data until 1984 when a bald
eagle in Maryland was captured and fitted with a transmitter powerful enough to send
signals to a pair of orbiting satellites.
Satellite tracking revealed details of some remarkable migrations, like the bar-tailed
godwit's annual flight from Alaska to New Zealand, during which the bird covers 11,000
km in about eight days without a single stop.
But there’s a serious limitation to satellite tracking devices: even with modern technology,
transmitters with enough oomph to send signals to satellites are still far too heavy for
small songbirds.
A slight improvement is to use GPS recorders, which can be smaller because they receive
rather than send signals to satellites – but they’re still too heavy for the smallest
songbirds.
Luckily, scientists have been clever enough to realize they don’t need satellite tracking
at all!
Instead, we can fit birds with a tiny device that includes a sunlight detector, electronic
clock, and memory chip, which together weigh as little as a raisin.
Lightweight light-recorders don’t broadcast so we need to recapture the birds to get the
data, but we can then use ancient navigation methods to reconstruct the bird’s daily
location over the course of its journey: the length of each day is an indicator of latitude,
and the time halfway between sunrise and sunset (that is, noon) is an indicator of longitude.
These clever geolocators have shed light on the world’s speediest migration: the great
snipe, which weighs about 170 grams, high-tails it from Sweden to Central Africa in just three
days, averaging 95 km/h.
Another marathon migrator, the Arctic tern, has long been credited with the longest migration
for its annual round-trip flight between the Arctic and Antarctic – an estimated 40,000
km.
But recent data from light-level geolocators show that terns actually travel more than
twice as far each year, possibly to take advantage of prevailing winds.
While scientists have learned a lot about the specifics of bird migration, they are
not the only ones contributing to migratory bird science.
Regular folks like you and me are also helping scientists learn about bird migration.
By pooling the observations of thousands of eager birdwatchers who contribute data to
online databases, scientists can learn about how migration timings, migratory stopover
locations, and breeding ranges are changing over time, which would be tough to study with
GPS locators alone.
So an investigation into migration that began with inquisitive regular folks watching birds
is now back to, well, inquisitive regular folks watching birds.
You might even say we've migrated full circle.
We had so much fun working with the students of Tebughna school.
and we are thrilled that we had the opportunity to share their work with you.
Remember those bird researchers we mentioned at the start?
They’re all part of Nate Senner’s research lab at the Department of Environmental Conservation
at the University of Massachusetts Amherst.
Thanks to funding from the National Science Foundation, they’re not only able to spend
time working with the local community, they're also helping to crack the secrets of long
distance migration.
Every spring, Nate and his fellow researchers migrate up to Alaska to slog through muddy
bogs in order to study Hudsonian Godwits, which take a marathon trip up from Chile every
year.
The scientists search for their godwit nests, count eggs and babies, and identify birds
that they banded in previous years, they monitor the food godwits eat, and the predators that
eat godwits as they try to learn more about the one of the world’s most impressive migrators
and understand how it’s navigating challenges like climate change and habitat loss in an
ever-changing world.
To learn more, visit SennerLab.com