Apart from a strip of the north and west of the main island, where crops such as potatoes are grown with irrigation, the land is arid. With a very hot dry summer, a mild winter, and brackish groundwater, the plants need adaptations in order to survive. Nevertheless, 196 species of higher plant have been recorded here, as well as about seventeen species of terrestrial mammals, many birds and reptiles, and many migratory birds visit the islands in autumn and spring.