Black vultures have killed and eaten several calves on Tom Karr’s cattle ranch in southeastern Ohio, a loss he says didn’t happen two decades ago. Now it happens regularly. It’s a problem faced by many livestock farmers and one that may grow worse as the scavenging birds’ range expands northward, in part due to climate change. Lobbying groups have been pushing for legislation that would allow landowners to kill more of these birds, which are protected under the Migratory Bird Treaty Act. But some experts say more research is needed to better understand the impact on livestock. They also caution that removing these scavengers from the ecosystem could have lasting negative consequences.