hornets will defend their nest, or hive. depending on the species of hornet, they will do this in a radius of between . concussions within that radius should be avoided. if they are disturbed often, they will make this radius bigger. there are specially trained people who can move hornet nests - note that in many parts of europe, the hornet is an endangered species; killing a hornet, destroying or disturbing a hornet nest can lead to a fine.