President Trump has been promising to build a wall along the U.S.-Mexico border to prevent illegal immigration into the United States. But biologists say it could harm animals like the Mexican gray wolf, mountain lions and jaguars that roam freely across the border.

Here & Now's Robin Young speaks with Vicki Croke (@TheWildLifeWBUR), host of WBUR's The Wild Life blog, about the proposed wall's impact on animal habitats.