A Mexican gray wolf
Scientists say a continuous border would make it difficult for endangered animals such as the Mexican gray wolf to disperse across the border to reestablish a population or bolster a small existing population. Susan Montoya Bryan/AP

More than 2,500 scientists have co-signed a paper describing the “significant” harm to wildlife posed by infrastructure on the U.S.-Mexico border.

More than 2,500 scientists from the United States, Mexico, and around the globe signed a paper published on Tuesday in the journal BioScience, warning that barriers along the U.S.-Mexico border are causing harm to biodiversity and that the continuous wall urged by President Trump would magnify this harm. The scientists, hailing from 43 different countries, called on the U.S. government to consider the ramifications of the wall for wildlife populations and not to reverse past investments in binational cooperation toward conserving the borderlands.

“We are trying to give a voice to the species, to the animals and plants that live in the borderlands areas, because people tend to think it’s just a barren area with no life,” Jennifer Miller, a co-author of the paper and a senior scientist at the conversation group Defenders of Wildlife, told CityLab.

The U.S.-Mexico borderlands cover six eco-regions and support abundant wildlife. The border bisects the ranges of some 1,500 native animal and plant species, including 62 listed as critically endangered, endangered, or vulnerable by the International Union for Conservation of Nature (IUCN) Red List.

The paper argues that border barriers and the infrastructure that supports them—such as roads, lights, and operating bases—have major consequences, killing animals either directly or through habitat loss, fragmentation of habitats, and eroding soils. The border also cuts off or splits wildlife populations’ access to water, food, and birthing sites.

A family of javelinas encounters the wall on the U.S.-Mexico border in southeastern Arizona. (Matt Clark/Defenders of Wildlife)

A continuous border wall could split the population of a species such as jaguars into two groups on either side of the border, cutting off each from vital resources on the other side and, in the long term, decreasing the population’s genetic diversity. Miller told CityLab she would expect that some animals, including peninsular bighorn sheep, wouldn’t be able to travel to access water in a drought.

The wall that President Trump made a centerpiece of his campaign so far remains unbuilt. Congress passed a spending bill in March with $1.6 billion in border-barrier funding; Trump wanted $25 billion. But the country’s southern border is already built up. As of 2017, DHS had constructed some 650 miles of pedestrian and vehicle barriers, which are serviced by almost 5,000 miles of roads, as well as miles of undesignated routes created by off-road patrol vehicles. Human activity, light, and noise all have adverse impacts on wildlife along the border.

Defenders of Wildlife’s Robert Peters, the paper’s lead author, said that these effects will worsen as the wall becomes more continuous, preventing species from passing back and forth. “As those gaps are progressively filled, we can expect the harmful effects of the wall to be greatly increased,” he said. The paper estimates that 17 percent of 346 species the authors analyzed could disappear from the U.S. if a continuous border wall is built.

The Real ID Act, which Congress passed back in 2005, allows the DHS to waive any laws that slow the wall’s construction in the name of national security. With exemptions to laws like the Endangered Species Act (ESA) and National Environmental Policy Act (NEPA) possible, wall construction can go ahead without analyses of environmental impacts or a search for less damaging strategies. DHS has issued eight waivers since 2005 in each of the U.S. border states, which includes three issued by the Trump administration in 2017 for California and New Mexico border construction.

The authors of the BioScience paper “urgently advise” four measures. First, they call on Congress to require adherence to all environmental laws in any future appropriations for border construction and operations, and to bar waivers. For areas where waivers have already been issued, they say DHS should analyze impacts and mitigate negative effects. They also want DHS to perform “rigorous pre-planning and pre-implementation surveys to identify species, habitats, and ecological resources at risk,” as well as mitigate “as completely as possible any environmental harm resulting from projects.” Finally, they urge DHS to facilitate scientific research in the borderlands.

Rurik List, one of the paper’s co-authors and a professor of ecology at Universidad Autonoma de Mexico, told CityLab, “As a Mexican, I have probably no right to ask the U.S. government to apply its laws. But when we are talking about the effects on binational ecosystems and species [and] their persistence in the long term that depends on the border being open to movement of these species … then we are not talking only about the United States.”

The security buildup at the border has a chilling effect on scientific research, the authors say. List has performed research in the border region since 1993 and says it has become more difficult. In another Defenders of Wildlife report published in April, he said, “We used to visit or work frequently with colleagues and landowners from the other side of the fence. The crossing was easy and the border agents friendly, but now the interaction has stopped. It’s harder to gain access, dangerous to move around, and there is a feeling of not being welcome.”

But the vulnerability of animal and plant species in the region is the paramount concern. “Conservation of very important species in the border region depends on [the animals] being able to be in both countries,” said List. “We have strong evidence of that.”

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