These are eight prototypes for the proposed border wall between the US and Mexico.
Customs and Border Patrol commissioned these designs and they’re on display just outside
of San Diego.
Some have rounded tops so that ropes can’t be hooked on.
Others have gaps so guards can see the other side.
Some are concrete, others incorporate steel and other materials.
They’re designed to keep people out.
But the border doesn't all look like it does in San Diego.
You can find pockets of rich biodiversity, including endangered species that move back
and forth across the border.
And that raises the question — when we design borders to divide people, what happens to
the natural world around them?
The US-Mexico border currently has about 650 miles of physical barrier that looks something
like this, while about 1,300 miles are unfenced.
Overall, this border region is home to an incredible array of species: you can see that
there’s a high concentration of diversity of amphibians, reptiles, and mammals right
along the political boundary.
Building a wall along these areas threatens that diversity.
Parts of the existing 650 miles of border wall have already impacted rare and endangered
species.
And in the Rio Grande Valley in Texas, where 33 miles of new barriers are scheduled to
go, the wall can't be built on the boundary itself.
The river forms a natural border, so construction has to happen on US territory.
That means a wall here would cut through several protected parcels of land like this, creating
almost 6,500 acres of inaccessible “No Man’s Lands”.
And that poses a unique problem for animal movement.
The immediate problem is with flooding.
Along the Rio Grande are floodplains that fill up when water levels rise from torrential
rains.
When that happens, reptiles and mammals have to move to safety.
But installing an impermeable wall essentially creates a dam: so when water rises, these
animals would be trapped.
In the long term, structures that limit animal migration can have serious consequences for
their survival.
When a population is separated by a barrier, its gene pool can be split up.
That means reduced genetic diversity in each population, which leads to higher levels of
inbreeding and an increased risk of extinction.
For the endangered ocelot, that process is happening right now.
The species is down to two small populations in the US and Mexico.
Border walls have been linked to a decrease in their populations and diversity.
Any additional barriers would put their survival even more at risk, and make the possibility
of re-connecting those two populations pretty much impossible.
Some argue that small crossings or barriers with occasional gaps would help animals like
the ocelot to pass through.
But those design features don’t take animal behavior into account.
Typically, building a barrier requires surrounding areas to be totally cleared of vegetation
for roads that border patrol can drive on.
The area is often lit with bright stadium lights too.
For animals accustomed to traveling at night under the cover of vegetation, that’s not
a welcoming environment to use a small opening.
In 2014, researchers placed cameras along the Arizona border, and found that the presence
of humans and most animals dropped after fence installations.
But where the fence ended, human presence increased dramatically, while animal presence
dropped.
So humans can figure out ways around, over, or under a barrier.
Animals often can’t.
There’s one big reason why habitats like those in the Rio Grande Valley are vulnerable
right now.
Along these areas, the Department of Homeland Security has the authority to waive environmental
laws for border wall projects.
So they can build a wall anytime with no restrictions.
Nature isn’t supposed to be the target of political barriers — but with a wall like
this, it might stand to suffer a lot of the consequences.
Thank you so much for watching episode 2 of By Design.
To film this story I went down with our science editor Eliza Barclay, to the border of Texas and Mexico.
I highly recommend that you check out more of the reporting that she has done on this issue.
Those links are down below.