An adult wolf needs around 2 to 4 kg of meat per day. It can eat up to 11 kg of food at a time but can also go without sustenance for two weeks.
The wolf's natural food comprises large to medium-sized, wild ungulates. Red deer, wild boar, roe deer, elks and reindeer are the wolves' main prey in Europa. Wolves in northern America primarily feed on whitetail deer, elks (moose) and wapitis. Carrion, fruits and small mammals are also part of the wolves' diet.
Wolves are extremely adaptable in choosing their food. They hunt and kill the prey which they can access and defeat most easily and effectively. Apart from old, sick or weak animals and those that are less able to defend themselves, these are mainly young animals. Depending on the availability (especially availability of young animals) and accessibility of food, the composition of the wolves' diet may vary according to the season or over the years.
Wolves mostly forage on one or a few prey species that are particularly abundant in their territory. Roe deer, for example, are very common and thus the wolves' main prey in the Saxon part of Lusatia. In eastern Poland, there are fewer roe deer but more red deer so that wolves primarily feed on red deer in this region. The Great Plains wolf in North America, for example, (almost eradicated in 1926, it has meanwhile regained a stable conservation status) is specialised in hunting a single prey species, namely the large northern American bison.
Wolves as adaptable opportunistic feeders are also able to survive in areas heavily influenced by human activities. Should their natural food resources run out, if the number of game animals severely drops due to human hunters or the game animals are displaced due to the destruction of their habitats, for example, waste or domestic animals which are not appropriately protected can become the wolves' primary food. But attacks on livestock may also occur in areas with a high game population. This means that wolves do not only kill and consume domesticated animals if they do not find sufficient wild prey. They simply hunt prey which they can defeat easily. They do not differentiate between animals that are "right" or "wrong" prey from a human perspective. Unprotected livestock is particularly easy prey. Sheep and goats are particularly easy to hunt as they are small in size, have almost no effective defence or escape behaviour and are extensively kept in free range conditions.
Please refer to Foraging and feeding ecology of wolves for more detailed information on the wolves' diet in Lusatia.