The catalog of Os Ancares, that includes two slopes, consists of 1,028 vascular plant species and subspecies.

Of the 75 species of reptiles and amphibians living in the peninsula of Spain and on the islands, 27 are present in Os Ancares.

Among birds, passerines are important for good representation, followed by accipitrines, among which are the short-toed eagle, the goshawk, abundant hawks, buzzards and the hen harrier.

At the beginning of Chapter XXXIX of the Part 1 of Don Quixote, a secondary character, the captive companion of Zoraida, says she is from "Somewhere in the mountains of León".

"[That] was my first lineage, with whom the nature of fortune was most grateful and liberal: though, admist the penury of those parts, my father passed for a rich man..."[3]