The fauna of the Republic of Macedonia has a complex zoogeographical structure. It contains faunal elements of different origins and is characterized by a high degree of relict and endemic forms. Taxonomic diversity is also present; the total number of animal species reported until now is 10,354.
The fauna of Macedonian forests is abundant and includes bears, wild boars, wolves, foxes, squirrels, chamois and deer. The lynx is found, although very rarely, in the mountains of western Macedonia, while deer can be found in the region of Demir Kapija. Forest birds include the blackcap, the grouse, the black grouse, the imperial eagle and the forest owl.
The three natural lakes of the country represent a separate faunal zone, an indication of long-lasting territorial and temporal isolation. The fauna of Lake Ohrid is a relic of an earlier era and the lake is widely known for its letnica trout, lake whitefish, gudgeon, roach, podust, and pior, as well as for certain species of snails of a genus older than 30 million years; similar species can only be found in Lake Baikal. Lake Ohrid is also noted in zoology texts for the European eel and its baffling reproductive cycle: it comes to Lake Ohrid from the distant Sargasso Sea, thousands of kilometres away, and lurks in the depths of the lake for 10 years. When sexually mature, the eel is driven by unexplained instincts in the autumn to set off back to its point of birth. There it spawns and dies, leaving its offspring to seek out Lake Ohrid to begin the cycle anew.