Plants and animals are those generally common to middle Europe. Beeches, oaks, and other deciduous trees constitute one-third of the forests; conifers are increasing as a result of reforestation. Spruce and fir trees predominate in the upper mountains, while pine and larch are found in sandy soil. There are many species of ferns, flowers, fungi, and mosses. Fish abound in the rivers and the North Sea. Wild animals include deer, wild boar, mouflon, fox, badger, hare, and small numbers of beaver. Various migratory birds cross Germany in the spring and autumn.