Research by scientists suggests Donald Trump's plan to build a wall along the border with Mexico could do long-lasting damage to Texas wildlife. Norma Fowler and Tim Keitt of the University of Texas at Austin looked at what would happen if more of Texas' border with Mexico were to have barriers built along it. The scientists say additions could threaten endangered plants and animals as well as threaten ecotourism in Texas. Their concerns center on the damage to habitat caused by its construction and the roads needed either side.

At the moment there are only about 100 miles (160 km) of barrier along the 1,200 mile (1,900 km) border between Texas and Mexico – a low proportion for border states. With an equivalent to four or five lanes of highway, scientists think that each kilometer of wall would need between 12 and 20 hectares of land. That's 4.8 to 7.3 acres needed for each mile of barrier.

The research involved a review of 14 publications, including some that examine the effects of existing border walls and fences.

Loss of habitat

The scientists highlight Tamaulipan thornscrub ecosystems as a particular concern. "The living things that depend on it would lose access to some of the last remaining patches in Texas if the wall were built," says a University of Texas press release, paraphrasing Fowler.

In terms of specific plant life, the scientists draw attention to the endangered wildflower Zapata bladderpod, as its habitat coincides with the proposed barriers. The same goes for the threatened whiskerbush cactus. The barrier could also create problems for plants that rely on pollination by animals which would no longer be able to cross the divide.

The wall poses a threat to animal life too, the scientists say. They fear a barrier could do further damage to the already endangered ocelot, of which it's thought only 120 remain in Texas. The species has already been badly hit by habitat loss. The scientists also worry that the wall could also drive a wedge between ocelot and black bear populations. This could potentially mean populations in either Texas or Mexico are too small to survive, including the black bear population in Big Bend National Park.

The scientists point out that this fragmentation of species could also be a threat in Arizona. There, the threatened ferruginous pygmy-owl, desert bighorn sheep, jaguar, Sonoran pronghorn, and javelinas could be affected.

The scientists also flag that the wall's construction would be exempt from environmental review. They urge that reviews be carried out for each stretch of barrier.

Ecotourism

The wall could pose a threat to Texas growing ecotourism industry, too, the scientists say. They think it's likely that the wall would be set back from the Rio Grande floodplain, which could cut off several existing wildlife refuges popular with ecotourists. This could also hurt riparian forest species needing access to the river.

According to a 2011 study, ecotourism generated more than US$344 million in the lower Rio Grande Valley alone. Much of this comes from birdwatchers who go to see species like the green jay and the Altamira oriole.

"If ecotourism declines significantly because access to preserves has been impeded, there may be negative economic impacts on the region," the scientists write in a letter published in the peer-reviewed Frontiers of Ecology and the Environment. "On the other hand, if the barriers are not far enough from the river, they may trap wildlife escaping from floods, and may even act as levees, which tend to increase downstream flooding."

Measures

The scientists suggest that negative effects could be mitigated by using electronic sensors instead of physical barriers. Or, if barriers must be built, they suggest designing them to allow animals to pass through.

The research project is explained in the video below.