Builders contracted by the Department of Homeland Security (DHS) are installing roughly 50 “doggie doors” in sections of the US-Mexico border wall along Arizona and California.

And, as if on cue, wildlife experts are up in arms.

They argue the openings — about the size of an 8-by-10-inch piece of paper — are too small and will prevent larger animals from moving in their natural migratory patterns while also disrupting ecosystems. Experts fret population declines and even starvation.

Animals like skunks, badgers, foxes, opossums, weasels, rabbits, snakes, and desert tortoises can get through. But larger creatures — including mountain lions, jaguars, deer, and bighorn sheep — will be affected by their inability to move to the other side, according to National Geographic Magazine.

They’re also concerned about the low number of “doors” for such a long, sprawling fence.

The southern US border with Mexico is roughly 1,933 miles long, stretching from the Pacific Ocean to the tip of South Texas. Some 700 miles already have fencing in place, according to CNN, and the rest is undergoing the lengthy process of being contracted and built.

“This has got to be an obscene joke,” said Laiken Jordahl, an advocate for public lands and wildlife with the environmental group Center for Biological Diversity, bemoaning that only there’s “only fifty of these tiny openings.”

Christina Aiello and Miles Traphagen, two of the researchers for Wildlands Network, went to the wall to see the conditions up close and came away shaking their heads.

“We came out to look at the condition of the border where they plan on building a border wall,” Traphagen told KTSM El Paso news in a Border Report. “We can’t simply be throwing away all of our biodiversity and our natural history heritage to solve a problem we could do more constructively, with, you know, overhauling our immigration programs.”

To keep building the wall, the DHS is waiving several environmental laws to expedite the work.

“This is necessary to ensure the expeditious construction of physical barriers and roads. Projects executed under a waiver are critical steps to secure the southern border and reinforce our commitment to border security,” the agency said in a statement.

In response the criticism, Customs and Border Protection (CBP) spokesperson Matthew Dyman said the agency worked closely with the National Park Service and other federal agencies to pick the best placements for the passages, relying on existing data about the distribution of species and migration routes.