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Habitats Open Sea Having risen directly from the ocean floor as volcanoes, the islands we see today are the tips of much larger undersea mountains. Consequently, the coastal waters drop rapidly away in depth at short distances from the islands – the sea floor in the Canary Basin just off El Hierro is some 4,000m deep! Because of these great depths, oceanic cetaceans, seabirds and sea turtles regularly pass very close to each of the islands, which enjoy a diversity of species unparalleled in coastal Europe. Upwellings around the islands present rich feeding opportunities for both resident and migrant species. The coastal shallows have a chance to warm up in the summer, particularly on the more sheltered eastern coasts, and present excellent opportunities for snorkelling and diving. Many species of colourful sea fishes are present, some of which can be seen from shore in harbours and more sheltered coves. Rock stacks east of Porto Moniz, Madeira. There are 10main types of natural habitat in the islands, including the open sea . All the terrestrial habitats have to a greater or lesser extent been altered by humans, either through direct alteration, such as clearance of trees and shrubs, or by more indirect means, such as the pernicious effects of grazing animals, including rabbits and goats, and of introduced exotic plant species . Over large areas, much of the original habitat has been lost entirely . Nonetheless the remaining habitats still support a diverse and often endemic flora, which in turn supports a very interesting range of animals, including many endemic species . Elevational zonation of the remaining native vegetation is still very marked on the higher islands and results from variation in rainfall patterns . Such zonation is easily appreciated as you drive up through the high central mountains of Madeira, Tenerife or La Palma . Generally, coastal areas are drier, and the height and lushness of vegetation increases with elevation, as the mountains create their own clouds and precipitation . On the highest peaks, there is a switch back to more arid habitats above the normal level of the clouds . Northern slopes are typically moister than southern ones, so the same habitat zones tend to occur at lower elevations there . Steep-sided valleys, being more sheltered from the wind and sun than more exposed slopes, create their own microclimates, which allow mid-elevation habitat zones to reach further down the slopes and higher habitat zones to reach further up the mountainsides . 10 Offshore Islets There are a large number of offshore islets and stacks around the coasts of the larger islands. Some are too small and exposed to develop vegetation, but others are larger and harbour a fascinating flora and fauna, often including species that can exhibit different traits to their mainland counterparts. As these populations are often small, they are vulnerable to loss; unique forms of the Hierro Giant Lizard and Canary Islands Stonechat, for example, perished in the 20th century. However, many of the islets remain rat-free and, as such, provide vital refuges for large numbers of ground-nesting seabirds, most of which are otherwise restricted to the steepest slopes and cliffs on the main islands. These islets are also havens for the shy Mediterranean Monk Seal, which requires remote undisturbed caves on offshore islands in which to breed. Intertidal Areas Since the islands have such steep profiles, intertidal areas are rather limited in extent, particularly on the younger islands in the Western Canaries and Madeira. Rocky inshore reefs and rock pools provide feeding for a range of migratory shorebirds and egrets that are elsewhere more often associated with estuaries. On Fuerteventura, sheltered flatter shores hold pockets of salt marsh and saline lagoons that attract large numbers of shorebirds and gulls; this habitat is replicated on several islands in man-made salt pans. Broad white-sand beaches on Fuerteventura and Porto Santo also support wintering shorebirds and terns. FreshwaterWetlands Owing to the widespread presence of naturally porous bedrock and low rainfall for much of the year, natural freshwater wetlands are very scarce on the islands. This situation has been exacerbated by the damming of many streams in their headwaters as a source of water for both drinking and irrigation. On the wetter northern slopes of the larger islands, a few streams run year-round; even on the drier islands, sheltered barrancos may hold small pools of water all year. All permanent water acts as a magnet for dragonflies and amphibians and for birds in search of a drink or a wash, while the zone...

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