The Upper Rock Nature Reserve is a protected area on the Rock of Gibraltar that covers about 40% of the land area of Gibraltar. It was established in 1993 under the International Union for Conservation of Nature’s category Ia (strict nature reserve). It is known for its semi-wild population of Barbary macaques, and is an important resting point for migrating birds.
In the past, the Upper Rock was tree-covered. Most of the trees were felled for fuel during the Great Siege of Gibraltar between 1779 and 1783. Trees today mostly produce berries that are eaten by birds, who presumably dropped their seeds on the rock. The most common is the Olive. Carob and Nettle trees are also found. Trees have been planted along the paths, including the Stone Pine and Aleppo Pine. Both are native to the region, but the Aleppo pine is particularly common in dry, limestone regions. There was a drought in the 1990s when many of the introduced trees died, although the Aleppo pine fared better than others.
The tourist sees a waterfall while visiting; that is in fact the outlet for Gibraltars de-salination Plant.
Gibraltar, British overseas territory occupying a narrow peninsula of Spain’s southern Mediterranean coast, just northeast of the Strait of Gibraltar, on the east side of the Bay of Gibraltar (Bay of Algeciras), and directly south of the Spanish city of La Línea. It is 3 miles (5 km) long and 0.75 mile (1.2 km) wide and is connected to Spain by a low, sandy isthmus that is 1 mile (1.6 km) long. Its name is derived from Arabic: Jabal Ṭāriq (Mount Tarik), honoring Ṭāriq ibn Ziyād, who captured the peninsula in 711. Gibraltar is a heavily fortified British air and naval base that guards the Strait of Gibraltar, which is the only entrance to the Mediterranean Sea from the Atlantic Ocean.
Area 2.25 square miles (5.8 square km). Pop. (2007 est.) 29,257.
The peninsula consists of a limestone and shale ridge (the Rock), which rises abruptly from the isthmus to 421 m at Rock Gun, its northernmost summit. Its highest point, 426 m, is attained near its southern end.
The Rock’s slope is more gradual on its western side and is occupied by tier upon tier of houses that stretch for some 300 feet (90 metres) above the old defensive walls. Higher up, limestone cliffs almost isolate the Upper Rock, which is covered with a tangle of wild trees.
Gibraltar has no springs or rivers. An area of sand slopes above Catalan and Sandy bays has been sheeted over to provide a rain-catchment area, which was once the sole source of potable water for Gibraltar. The water was stored in a number of tanks blasted into the Rock. The rainwater was then blended with water pumped from wells on the isthmus or distilled from the sea. The catchment ceased to be used as a source of potable water in the 1990s, when a desalinization plant built in the 1980s was expanded, but it still is used as a service reservoir.
Barbary macaques monkeys have roamed the Rock for hundreds of years and are Europe’s only wild monkeys. Although free to wander, they are generally seen on the Upper Rock. The macaques were once protected by the British army in Gibraltar, and, according to legend, British dominion over the Rock will cease when these animals are no longer present; their protection is now the responsibility of the Gibraltar Ornithological and Natural History Society which feed them on daily basis (around 300 of them).