The Rock of Gibraltar nature reserve SAC/SPA has undergone several transformations in its habitats and uses. Habitats have ranged from a once (presumably) forested landscape to a totally denuded slope during the Great Siege, 1779 – 1783, to a succession of vegetation back to dense maquis with scattered patches of garrigue and pseudosteppe in recent times. More recently, the emphasis has changed to that of a Nature Reserve which remains, a tourist attraction with several tourist sites.
The Rock of Gibraltar SAC/SPA boasts a rich flora, with 363 species having been recorded within the boundary of the Nature Reserve (Linares 2003). The vegetation of the Upper Rock Nature Reserve is dominated by closed Mediterranean shrubland known as maquis (a tall, thick type of Mediterranean matorral), which consists of a dense community of evergreen, sclerophyllous shrubs that typically replaces evergreen woodland after fire or deforestation (Rocamora, 1997), as was the case with the Upper Rock following the initial removal of its Mediterranean woodland. Maquis habitats are not determined by any species of trees or bushes in particular (Tomaselli 1977), but the typical shrub genera that dominate in this habitat, depending on location, soil and other conditions, are Arbutus, Cistus, Erica, Olea, Phyllirea, Genista, Calycotome, Sarothamnus, Quercus, Ulex, Rhamnus, Pistacia and Myrtus (Rocamora 1997).
The Rock of Gibraltar, and in particular the Upper Rock Nature Reserve is dominated by a dense cover of mostly maquis, with some garrigue, and these habitats include many important fruit-bearing shrubs that support large passerine populations during passage periods and in winter (Heath et al. 2000). The slopes of the Rock also serve as a staging site for large numbers of passerine and near-passerine migrants. Most migratory western European species can occur at Gibraltar during the northward or southward migration periods (Cortes 1996). The passerine and near-passerine species that occur within the Nature Reserve on migration are listed in table 1, which shows that a number of these birds have an unfavourable conservation status within Europe.
In addition, many migratory birds of prey and storks congregate at the Strait of Gibraltar on their way towards their wintering grounds in Africa. When westerly winds blow across the Strait, Gibraltar itself sees the majority of raptor passage during both the pre-nuptial (northerly) and post-nuptial (southerly) migrations, and most of these birds fly directly over the Upper Rock Nature Reserve. The species that can be observed over the Rock on migration are listed in table 2.
Extending three miles to the East and South of Gibraltar and stretching all the way up to the median line to the West of Gibraltar, the marine SAC/SPA or Southern Waters of Gibraltar SAC/SPA has long been recognized as an important marine area due to its rich diversity in species and habitats. Sea cliffs and caves, reefs and sandy marine habitats all form part of the marine ecosystem found along the southern shores of Gibraltar. The abundance and richness of species is largely influenced by the strong currents and upwelling that are so characteristic of the Strait of Gibraltar. Seasonal abundance, due to migratory movements between the Mediterranean and the Atlantic, results in a multitude of pelagic and predatory fish along with cetaceans including the Striped and Common Dolphins. The latter cetaceans breed in the Bay of Gibraltar.
The Southern Waters of Gibraltar SAC/SPA is also located on an important migration route for seabirds. Many species stop over and feed within the marine SAC/SPA during their migratory journeys and some, such as the Cory’s Shearwater, forage in the marine SAC/SPA whilst breeding. Other species rely on the SAC/SPA during the winter in variable numbers depending on weather conditions (e.g. numbers of Gannets feeding inshore during storms).
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