If there's one activity we associate with birds, it's flying.
Soaring through the air, going wherever they want to go.
But not every bird can fly.
Let's learn about flightless birds and how they got that way.
Flight is amazing for escaping predators, hunting, and migrating.
Almost every bird uses flight this way.
But flight has a downside: it costs a lot of energy, so you have to find a lot of high-energy
food just to live.
It also limits how much body weight you can have.
So every now and then, in the right circumstances, a bird will throw off the restrictions of
flight and become a creature of the ground.
One of the ingredients that really helps birds lose the ability to fly is a predator-free
space.
So let's make one!
The fastest way to make a predator-free space is to cause almost every large land animal
to go extinct.
This happened when a giant asteroid hit the Earth and removed large dinosaurs from habitats
worldwide.
That might be a little excessive, so let's try something smaller.
The most common way to get rid of all the predators is to have a small island.
There's not enough food to support a population of meat-eating predators, but there is enough
food to support a population of plant or bug eating birds.
Now let's have a bird fly to this predator-free space.
There is plenty of food, so the bird can eat all it wants.
There are no predators, so the bird's offspring will survive and succeed not by flying, but
by eating lots of food and having offspring of their own.
These are new pressures which select how the species will develop.
Their bodies are selected to get bigger and stronger.
Their feathers are selected to become fluffy insulation instead of sleek, streamlined shapes.
Their wings are selected for small size.
The transition from flighted to flightless can happen in under 100 years, and it can
last until something changes on the island, like the re-introduction of predators.
So most flightless species don't last very long.
This sequence sound improbable, but it has happened many times.
Penguins.
Ostriches.
Invisible Rail.
Kakapo.
There birds are not related, and they all separately lost their ability to fly.
The Rails, especially, there are more than 50 known species that WERE flightless.
And we use the past tense here because while flightlessness does have its advantages, but
there is a problem that many, many species of flightless birds have encountered.
If a predator population comes to the island it can make the entire bird population go
extinct within a few generations.
So as humans have spread across the world, bringing dogs, cats, rats, and other predators
to small islands everywhere, the number of flightless birds has dropped dramatically.
The Dodo, the largest pigeon in history, went extinct after human hunting and invasive predators
came to the island.
The Rodrigues Solitaire, which was a flightless pigeon with a goose neck, went extinct due
to human hunting and invasive predators.
The Stephens Island Wren went extinct due to feral cats being introduced on its island.
In fact, here's a list of every flightless, or probably flightless, bird that is alive
in the world today.
And here is a list of every flightless bird that has gone extinct just since humans showed
up.
If you compare these two lines it is not a promising story for flightless birds.
But there are people alive in the world today who are trying to save flightless birds.
The Government of New Zealand is protecting the world's only flightless parrot - the Kakapo,
by moving them to predator-free islands, providing supplemental food, and tracking their recovery.
All species of penguins are helped by the creation of marine reserves to protect their
food sources and habitat.
So if you hear the story of the Dodo, and you're really sad that we have lost this unique
and interesting bird, and you really wish that the people of the day had done more to
save this species, here is the good news.
You are the person who can save these other flightless bird species today.
With your help we can save these unique birds and the interesting stories that their bodies
tell.
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Thanks for stopping by this week to learn what makes Life awesome!