Pine martens hunt in trees and on the ground. They like to roam in broad-leaved or conifer woodlands, and the destruction of these is a threat to the species. They find most of their food on the ground, and they hunt for small mammals, birds, insects, fungi, berries, birds' eggs and carrion (dead animals). Contrary to some opinions, they do not eat significant quantities of squirrels, red or grey. Pine martens avoid areas away from woodland or scrub, probably because other predators (especially foxes) can catch and kill them in the open.

Martens have territories that vary in size according to the availability of food. For males, the territory is about 10-25 square kilometres, and for females, about 5 - 15 kilometres. They are not aggressively territorial, some animals' territories overlapping those of others. Sometimes, however, they mark their trail with faeces ("scats"). even in places where they are at their most numerous, pine martens are thin on the ground compared with other carnivores like foxes, stoats and badgers.They can be very playful and curious in their behaviour.