A few years ago, a group of giraffes were placed in a field surrounded by enough acacia trees to ensure their food, but after a short time the giraffes began to get sick. The cause is the acacias. These, when the giraffe eats its shoots, releases a toxic substance to the other shoots that makes them toxic and also sends signals to the surrounding acacias that also make them toxic. The giraffes, therefore, in freedom, after eating from an acacia, move to others of several km to continue in these, but this in an enclosure was not possible.