Half of Latvia's soil is podsolic humus, which covers one-third of the country's arable land. Woodlands make up 41% of the country's territory, with one-half of the forests consisting of pines, birch, and firs. The woodlands and plant life support 14,000 different animal species. Species native to Latvia are the wild boar, Eurasian beaver, and brown bear. The routes of migratory birds pass along the Black Sea and over the country.