When individual meerkats sense danger while on watch, they alert the rest of the group. Meerkats are known to use a variety of vocal signals to communicate with each other. They howl for a long time to warn the rest of the clan about an approaching raptor and emit short double barks to signal a predator that is approaching the group on the ground. The individual territory of a meerkat group encompasses an area large enough to ensure that the group has everything it needs to survive successfully. This includes both hard and soft sandy areas, as the hard sand provides the perfect ground for digging their tunnels, but it requires more energy for meerkats to search for food in it.