and its adjacent islands. Over 40% of Saaremaa is covered with forests, most of which are mixed forests, but in some areas, one can find broad-leaved (deciduous) trees, which are relicts of plant communities of former milder climatic periods. Wooded meadows were common in Saaremaa before World War II, but many of these unique natural complexes have gradually become overgrown and thus converted into the ordinary forest. The same is true for alvars (limestone areas covered with thin soil and stunted vegetation). Once a typical and exclusive landscape element in Saaremaa alvars are now in decline. Nature conservation planning for Saaremaa now includes protection of the largest and most unusual alvar areas. Saaremaa has a wide variety of rare wildlife species, ranging from insects to seals. The smallest protected wildlife species in terms of size include the clouded apollo butterflies and Roman snails. The coastal areas of Saaremaa are well-known seal habitats; in fact, the indigenous gray seal can be found in three large permanent resting areas on the islets off the coast in the western and southern parts of Saaremaa. Nowadays, the local population of said seals is slightly increasing. Ringed seals can be encountered everywhere in the coastal waters of Saaremaa but, because of their timidity, it has not been possible to make an estimation of their number. The islands lie in the East Atlantic Flyway, a migration path of waterfowl. This "bird road" connects northeastern Europe with Arctic regions. Each year hundreds of thousands of migratory birds visit Saaremaa in spring and autumn. The barnacle goose, mute swan, whooper swan, eider, shelduck and a great many other bird species have been given protection status. But on the whole, the islands are somewhat poorer in wildlife species than the mainland. Neither mole, mink, nor otter can be found here, whilst the Eurasian lynx and the brown bear are infrequent guests. Kaali Meteorite Kaali is a small group of nine unique meteorite craters on Saaremaa. The largest of the craters measures in diameter and contains a small lake, known as Kaali järv ("Lake Kaali"). The meteor cluster had an impact velocity of and a mass of . At the altitude of the meteor broke into pieces. The largest fragment produced the main crater with a depth of . Eight smaller craters with diameters ranging from and depths varying from are all within of the main crater. The age estimates