The Iberian wolf is a subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 of grey wolf that inhabits the forest and plains of northern Portugal

Portugal

Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

 and northwestern Spain

Spain

Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

.
The Iberian wolf differs from the more common Eurasian Wolf

Eurasian Wolf

The Eurasian Wolf , also known as the, European, Common or Forest Wolf is a subspecies of grey wolf which has the largest range among wolf subspecies and is the most common in Europe and Asia, ranging through Mongolia, China, Russia, Scandinavia, Western Europe and the Himalayan Mountains...

 with its thinner build, the white marks on the upper lips, the dark marks on the tail and a pair of dark marks in its front legs that give it its subspecies name, signatus ("marked"). The subspecies differentiation may have developed at the end of the Pleistocene

Pleistocene

The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

 Ice Age

Ice age

An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

s due to the isolation of the Iberian Peninsula

Iberian Peninsula

The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...

 when glacier

Glacier

A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...

 barriers grew in the Pyrenees

Pyrenees

The Pyrenees is a range of mountains in southwest Europe that forms a natural border between France and Spain...

 and eventually reached the Gulf of Biscay in the West and the Mediterranean in the East.

Males can weigh up to 40 kilograms, with females usually weighing 10 kg less.
The Iberian Wolf lives in small packs.