(crickets chirping)
- [Narrator] The Great Smoky Mountains
and even the larger region of the
Southern Appalachian Mountains
are a treasure trove of biodiversity.
(creek rushes)
Forests and streams as well as the mountains and valleys
are filled with a seemingly endless
variety of life both large and small.
- And all of these things fit together
and help tell the story of the Smokies
and what we're trying to protect.
(crickets chirp)
- [Narrator] 20,000 different species counted so far
in Great Smoky Mountains National Park alone.
But this is the story of just one, tiny creature,
filling one tiny spot in that web of life.
Meet the Carolina Chickadee.
(gentle piano music)
- [Woman Scientist] Most all songbirds in North America,
most of our breeding birds are in decline.
And so if we know more about them,
it might enable us to be able to
better protect and conserve them.
- [Narrator] Scientists know some things
about this little bird.
It weighs about 0.4 ounces.
That's about the same as a half slice of bread.
The Carolina Chickadee is about five inches tall,
the wingspan is about eight inches across.
- Carolina Chickadees, they do a single brood in a season
so that means they have one shot at it every year
and if they fail, then they have to wait
'till the following year.
(gentle piano music)
- [Narrator] Like most songbirds,
the female Carolina Chickadee builds the nest.
Once the nest is ready, the female lays one egg per day.
Once there is a full clutch,
the female begins incubating the eggs.
- And that is a really critical time
for both themselves and the nestlings.
So they need to keep the temperature
of the eggs above a certain threshold
in order for them to develop properly.
- [Narrator] And it turns out nest building is
critically important to the survival of Carolina Chickadees.
The better the female builds the nest
the better she'll be able to take care of her little ones
because she will be healthier.
- So, being on the eggs and keeping them warm
means that they're not out foraging
and taking care of themselves.
So they have to balance their activity
to take care of the eggs and keep them
at an optimal temperature for development
and taking care of themselves so that
they can survive to reproduce again in a following year.
And it seemed like a good opportunity for us to ask
what is really critical about female behavior
that's gonna lead them to have
a lot of reproductive success?
- [Narrator] But to study nesting behavior,
researchers need to observe nests.
Nest boxes were placed at varying elevations.
That meant different temperatures
and that translated into different times for nesting.
Temperature sensors were placed
outside and inside the boxes as well as
inside the nests for comparison.
- These are just a quick example
of some of the variations that we find.
Like this is a smaller nest, so you can see that they
typically will build a layer of moss
and then they'll build the cup on top.
You can see they'll use a little grass
or fur that they find and you can see how
this one, of course, is so much taller and deeper
and a little more insulated than this one.
- [Narrator] Researchers found
the female Carolina Chickadee didn't build
one standard type of nest.
The style depended on where the nest box was located.
- [Traci] So the females want to try to reach
about 100 degrees Fahrenheit in the nest temperature.
Like if the eggs are not kept at a proper temperature,
then the embryos won't develop correctly,
so they won't hatch and as far as the nestlings,
when they're first born, they're unable to
regulate their body temperature for three to four days
so they really depend on warmth from their mother
and from the nest to regulate their temperature.
- [Narrator] Different types of insulation
and different types of nest construction
were used to adapt the nest to the climate.
That allowed the female to stay stronger
and take better care of her nestlings.
- This is an investment that they're making
that might help them when they're incubating
so it might alleviate some of the pressure of
being on the nest so often to keep
the temperature of the eggs up
because if there's a lot of insulation in the nest,
then the temperature of the eggs
might fall more slowly when she leaves the nest.
So she can be off for a little bit longer.
(gentle piano music)
- [Narrator] That means the female can forage longer
and be stronger and healthier.
The question, what happens as the climate changes?
- [Barbara] It's, there's probably a lot of factors
that are involved with decline
of songbirds in North America.
But the fact that these birds have one shot
at reproductive in a season is
probably gonna be a big factor for Chickadees.