Last year, police in the Netherlands were ready to deploy a team of eagles to take down rogue drones. Now the police say they’ve stopped using the birds because training them is more expensive and complicated than they anticipated, reports Nos, as spotted by Gizmodo. The eagles wouldn’t always do what they were trained to do, and the police also doubted if the birds would perform well outside of their controlled training environment. Dutch police bought four sea eagle chicks after completing their trials last year.

When Dutch police first released a video showing the birds of prey grabbing drones out of the air with their claws, animal rights activists also voiced their concern. "If an eagle can not catch his prey, he may become so frustrated that he picks up something else. Eagle talons are so strong that it can easily pierce a child's head,” Robert Muster, a falconer, told the NL Times last year.

The Netherlands was the first country to tackle rogue drones in this way, and Dutch police say they’re now looking at other options as they move the eagles to a shelter. The US Air Force, meanwhile, is researching falcons and how they target prey to develop defense systems against drones.