Croatia lies on the eastern coast of the Adriatic Sea. Since Croatia extends over the central European migration corridor, and partially over the western one, it is the spring/autumn passage and the wintering area of European migratory birds.
Croatia has a surprisingly varied range of landscapes for its size of 56.542 km2, but basically there are four main kinds of landscape - the lowlands, a chain of inland mountains, the coast, and the archipelago of more than 1000 islands in the Adriatic Sea.
Croatia has two distinct climate zones: the coast and the islands have Mediterranean climate, while the plains and the mountains of the inlands have a typical continental climate. Locally, there are great variations in the levels of temperature and the quantities of precipitation, due to abrupt large differences in the relief (elevation).
The habitats of Croatia fall in four basic zones - Pannonian, Continental, Alpine and Mediterranean.
The lowlands lie in the north-east, in Slavonia. Arable land prevails, with ample fields of wheat and corn. Grassland basins, or depressions, that fill with water when rivers are in flood, called Polje, are the relief particularity of this area. Fishponds and marshes also add to the diversity of the landscape. Large rivers of the area, the Danube, Sava and Drava, are partially lined with woods of oak, willow and poplar. The plains of Slavonia are covered with snow in the winter.
Between these plains and the Adriatic coast, runs the Dinaric Mountain range. The scenery is impressive and wild, although the mountains are not particularly high. The landscape is mostly forested, with karst elements - sinkholes, gorges and caves. Mountains in the south are higher and rougher than those in the north. The most famous landscape of the Croatian inland is Plitvice, a forested gorge with 16 lakes that fall into each other in countless waterfalls of all sizes. The climate in this area is typically continental, with harsh snowy winters and warm summers.
The Adriatic coastline is exceptionally indented, its shores are mainly rocky and pebbly - with several sandy exceptions - with expanses of Mediterranean shrub. Its Mediterranean climate is characterized by mild winters and very warm and dry summers. Behind the coastline, but still in the coastal area, there are the rough Velebit Mountain range and the Krka River, both plentifully rich with various karst formations.
Due to the above characteristics, in Croatia's rich avifauna we may find all of the following categories: montane, lowland, boreal, wetland and marine; furthermore, many bird species of the Croatian avifauna are classed as threatened: 69 of them on the European level and 21 of them globally.