Okay.

When will I see you again?

Well, I'm going to.

You have a good time.

Bye bye.

This is how nature works!

Theme Music Every fall, thousands of people head south for the winter, down where it's warmer and more comfortable for them.

Then in the spring, they come back north for the summer.

Some people call these human migrators snowbirds.

Real birds do the same thing, and so do lots of other animals.

For them, it's a matter of survival.

It's not something they decide to do, but an inborn behavior.

This seasonal movement of animals from one habitat to another is an adaptation to an environment.

It's called migration.

Animals migrate for lots of different reasons.

Some animals migrate to find food or a place to hibernate.

Others migrate to mate, give birth, or raise their young Where a change of seasons reduces an animal's food supply each year, some animals have adapted by migrating.

As the food supply in one place dwindles, they go where they're more likely to find food.

For example, when the weather turns cold, few insects survive.

So the birds that eat them, like warblers or swallows, have less to eat.

These birds survive by migrating to a warmer climate where more insects are available.

If the food is there but buried in deep snow, some animals might have to travel to a place where it's easier to find.

In Arctic winters, caribou go where they can reach grasses, lichen, and mosses.

In the Rocky Mountains, elk migrate into valleys for a similar reason.

Another reason to migrate is to find the right conditions to hibernate.

Little brown bats live in trees and buildings during warm months.

To hibernate they migrate to caves where moisture and temperature stay about the same.

These conditions keep them from dehydrating and help them conserve fat.

Some animals migrate to breed.

Atlantic salmon begin life in a river and migrate to the ocean.

After several years, they move back upstream to lay eggs and begin a new cycle.

Frogs and toads often move to breeding ponds and lakes.

Some sea turtles return to the same sandy beach where they hatched to lay their eggs.

Migrating animals usually follow the same route each year.

Some find their way with landmarks like rivers and mountains.

Some use the sun and stars, or smells, and some even the Earth's magnetic field.

Migration is dangerous.

In a typical songbird migration, birds lose half their weight and many die in storms, are killed by predators, or hit tall buildings or communication towers.

And changes in the environment can make a hard trip even harder.

Cleared forests, drained wetlands, and dammed rivers can damage important migratory habitats and resting places.

Migration is not a vacation for animals like it is for human snowbirds.

It is an adaptation that is a matter of life and death.

Music Many kinds of migratory birds spend their time around the nature center.

Let's go see Dave and find out more about them.

Music So, are we ready to band some birds?

Oh, we are.

I just caught some of these tree sparrows.

Oh, if I can get a hold of one of these out of the gathering cage, we'll be able to do that.

We've learned about migration by banding birds.

We actually can learn a lot about banded birds if we can catch them.

But banding is just one tool that biologists use to study migration in birds.

Do you want to hold the band?

Sure.

Well, these tree sparrows we know from banding that they migrate some distance, actually about 1500, 2000 miles from the subarctic, down here for their winter.

And the band just allows us to identify an individual bird.

And once we know that it's an individual bird, then we can keep track of it.

Are there any other ways to capture birds?

Well, there is.

There's, there's three basic ways.

One is to use traps like we have here, like this funnel trap, or like those cage traps up there and feeders over there.

But most of the birds are actually caught in mist nets.

Just going to weigh the bird right here.

So can anyone band birds?

Well, not just anyone can, actually.

There's some 3000 odd banders or banding stations across the country.

And so you have to be licensed or permitted by the U.S.

Fish and Wildlife Service and also by the state, usually conservation or wildlife department or organization.

And that's just done to make sure that the people who are banding birds can identify the birds can handle them properly and also record the data that you request.

Want to let this guy go?

Sure.

Okay.

Put out your hand, and just spread your fingers apart, and I'm going to put his head right between your fingers, and then, okay, now I can just close them gently around.

Oops.

Let's get him in there right.

One, two, three.

And just roll him over to your finger.

Fly, be free!

Neat, huh?

Yeah.

So what is the most interesting type of bird you ever caught?

I think it was actually a tree sparrow.

Just like this.

Last winter, I recaptured one that was at least six years old from the time I banded it.

So that's a lot of trips back and forth.

And when you consider it can be up to 2000 miles or maybe even more to the subarctic where that bird spent its summer, it's quite a long distance.

But, you know, the distances birds migrate can really vary.

Let's take a look at some raptors that are migrators.

Music Let's look at the way three raptors migrate.

Raptors are birds that capture food with their feet or talons.

Broad-winged hawks are long distance migrators.

In summer, they live in deciduous woodlands in the eastern United States and southern Canada.

In fall, they fly all the way to the Neotropics.

The Neotropics stretch from the Tropic of Cancer to the Tropic of Capricorn.

Broad wing hawks have full black and white bands on their tails and wide wings.

They nest in mature trees 10 to 80 feet off the ground, sometimes using old bird and squirrel nests.

Broad-winged hawks usually have 2, 3, or 4 chicks.

Both parents help take care of the young.

Although these hawks are often seen soaring, they do most of their hunting from low perches in the woods.

They use sharp talons to snatch and hold their prey.

Broad-winged hawks eat mostly small rodents, but they’ll also eat reptiles and amphibians, insects, and occasionally birds.

In early September, broad-winged hawks begin to migrate.

They use thermals to travel.

Thermals are bubbles of warm air that rise off the earth.

The hawks rise in spirals to the top of the thermals and slowly glide down until they reach the next one.

Hawks can use thermals to travel as far as 200 to 300 miles in a day.

They also migrate along mountain ridges using updrafts or winds that are forced up over the mountains.

Using thermals and updrafts over land helps hawks conserve energy on their long migration to Central America and northern parts of South America.

Red-tailed hawks are short- distance migrators.

In the northern part of their range, snow often covers the ground in winter.

Meadow voles are a large part of the hawks’ diet, and they burrow beneath the snow where they're hidden from view.

If hawks can't find enough other small animals to eat, they migrate south where there's little or no snow cover.

You often see red-tailed hawk sitting on telephone poles or and trees at the edge of meadows and open fields.

They have excellent eyesight, and they can spot small rodents up to a half a mile from their perch.

Some birds, like the snowy owl, migrate under special circumstances.

Most snowy owls live in the Arctic year round.

Their main source of food is the Arctic lemming and lemming populations rise and fall.

When lemming populations go down, some snowy owls migrate to southern Canada and the northern U.S.

in search of food.

Younger birds are more likely to migrate south because they have less experience catching food.

As fall approaches, migration begins.

Shorter days and the colder weather affects the food supply of raptors like the broad- winged hawk and the osprey.

Sara and Davis are going to spend the day hawk- watching, helping Ian McCleod with his annual hawk count.

Music Hey, Sara.

Hey, Davis.

How are you?

Good.

How are you?

Doing very well.

Why is this such a good place to watch hawk migration?

This is a great place to look for hawks, because we're nice and high up.

We're over 2000 feet here.

We got a wonderful view.

We can see, oh, certainly 180 degrees around us here.

So as the hawks are coming through, they're heading south, coming from the north, we can see them coming from the north.

Like that one right there.

Look right above us.

See the broad-winged hawk cruising over.

Heading south for South America.

How do they know when to migrate?

Well, they are starting to find that the food is disappearing, those frogs and toads and lizards that they feed on, the broad-wings in particular, they're starting to disappear into the into the woods and on the rocks.

And so they they know that it's time to start heading south, and then they wait for the right weather conditions to make it easy for them to fly all the way down to South America.

How do they know where to migrate?

Well, that is a great unanswered question.

I have no idea exactly how they do it.

Certainly, you know, the adults that have migrated before know where to go.

You know, there's always some that have been down in the tropics and come back to nest here in this area.

And then they head south again.

So they've been there before, but at some point, I guess there had to be a hawk that did it for the first time.

And how they knew exactly where to go is a mystery.

But certainly these broad-winged hawks that we'll be seeing in big numbers, they move together and kind of follow each other.

So they're kind of learning from each other, and the young ones certainly follow the adults or probably follow the adults.

We don't really know.

Music Do hawks make makeshift nest to sleep in, or do they just sleep in a tree on the way to South America?

They'll just sleep in a tree, they’ll just come down at the end of the day and just find a nice branch somewhere.

It's actually, sometimes you can see them do it, they’ll be circling around and just go (makes noise) just drop out of the sky and go down into the woods and they'll just, you know, maybe hunt for a little while, find a nice branch out of the wind.

If it's cold at night, they'll kind of tuck into the vegetation and just sleep and then get up the next morning and circle around, maybe hunt a little bit and then continue on their way.

Is there any other place around the country where we can see migration?

Yeah.

Lots of places.

Throughout the country you can find migrating animals, migrating birds, butterflies, dragonflies.

Because a lot of them are, you know, coming from the northern part of the country and funneling down into South and Central America.

So you just got to get out in the right place, get up the mountain top in September or October, look up and see what you can see.

What have we learned today?

Migration is a behavioral adaptation that occurs when animals move from one place to another.

Like all behavioral adaptation, migration increases a species’ chances of surviving and thriving in the natural world.

Animals migrate for lots of different reasons.

Some animals migrate to find food or a place to hibernate.

Others migrate to mate, give birth, or raise their young.

Now you know how nature works!

Theme Music Major funding for Nature Works was provided by American Honda Foundation.

Additional funding was provided by Alice Freeman Muchnic, Alice J. Reen Charitable Trust, Cogswell Benevolent Trust, the Finisterre Fund, Greater Piscataqua Community Foundation, Morgridge Family Trust, the Natural Areas Wildlife Fund, Rawson L. Wood.

(animal noises)