The Sierra de Gredos mountain range lies in central Spain within easy reach of Madrid, and much of it has a Regional Park status. This majestic stretch of mountains lying across the centre of Spain like a titanic rampart reaches its highest point at the Pico Almanzor (2,592m/7,776 ft).
Until 1834 only shepherds moving their flocks had reached some of the remote and inaccessible alpine valleys of these mountains. At the beginning of the XXth century, in 1905, the Sierra de Gredos became of interest when King Alphonso XIII created the Gredos hunting reserve, to protect the Capra Pyrenaica Victoriae - the wild Spanish ibex. Only a few wild goats were left, but now the Sierra de Gredos has one of the largest remaining populations. Alphonso XIII constructed byways to reach the highest peaks of the Gredos and its main glacial cirque and lagoon (Laguna Grande).
His hunting lodge in Navarredonda de Gredos (built in 1928) has been restored and was the first National Parador to be opened in Spain. The absence of population in the mountains of the Sierra de Gredos has contributed in keeping the nature of Gredos intact until the present. The villages were settled in the valleys and they still hold their uniqueness in their architecture and traditions.

Geography - Geology
The Sierra de Gredos mountain range is situated between the provinces of Avila, Cáceres and Salamanca, crossed by the Duero and Tajo rivers. It is the main range of the Sistema Central and covers 140kms, from east to west. To the east, the crooked elbow formed by the Alberche river, on its way to meet the Tajo, divides the Gredos from the Sierra de Guadarrama (Madrid). To the west, the trench of the Aravalle river separates the Gredos from the Sierra de Béjar (Salamanca).
The Gredos are divided into three parts: the Eastern Massif, between the Peña del Cadalso and the Puerto del Pico; the Central Massif (in the valleys of which our rides take place), including the Almanzor peak; and the Western massif, comprising the mountains west of the Puerto de Tornavacas.
The name of Gredos seems to derive from a Celtic root that refers to the whiteness of the snow. The Sistema Central was also named Iuga Carpetana, after the Carpetani pre-Roman population.
The Sierra de Gredos granite formation dates from the Herzynian Orogenesis in the Paleozoic period (350 to 200 million years ago). The present orography was formed in the Alpine orogenesis (40-20 millions of years ago), when the main mountain ranges of the earth were formed: the Himalayas, the Rocky Mountains, the Alps, the Pyrenees. This was also when the African continent (Gondwana) pushed against the Eurasian continent (Ankara). The formations of the Central Spain broke and gave birth to the Sierra de Gredos. The most striking differences are between the northern slope and the south face: the latter plunges abruptly from the highest peaks (at more than 2,100-2,500m/6,900-8,200feet) to the 300m (980 feet) of the Tiétar valley. The northern side of the Gredos consists of hills that rise by easy steps from 1,400m (4,600 feet).
Finally, the present relief of the Gredos is due to the erosion in the Quaternary Ice Age (10,000 years ago), when enormous glaciers carved out this wilderness in the hard granite rocks of Central Spain. The result of this erosion was the creation of a network of glacial basins with lagoons and gorges surrounded by high peaks and rock pinnacles. The glaciers of the Gredos, together with the ones in the Sierra Nevada (Granada), were where the most southern ice of the European glaciation could be found.
As a consequence of the high mountain climatic conditions, the north watershed of the Gredos preserves some unique flora and fauna of the glacial period. Glacial cirques, green alpine pastures, lakes and groves of scotch pine, with examples more than 40 metres tall, make up the northern face of the massif, which is characterised by a luminous atmosphere and mild summer temperatures.
The traditional husbandry in this region has allowed a harmony to exist between man and nature all the way up to the present day; it is evident in every corner of the Gredos. The mountain farming and cattle-raising which is widespread in the Gredos and the rational exploitation of forestry permits man here to co-exist with the regions unique flora and fauna.

Flora
The Gredos is a paradise for botanists for its diversity of ecosystems rich in wild flowers. There are at least 11 species, which are endemic to the Gredos (only found in this region). Although the altitude is not especially great, the Cordillera happens to lie in one of the coldest zones in Spain, and temperatures resemble those of much more alpine regions. The northern slope supports a sub-alpine flora, with great stands of pine, large tracts of Genista purgans -Piorno serrano- and rich meadows. The southern slope borrows its sub-tropical flora form the Valle del Tiétar and La Vera (the so-called Andalucía de Ávila), with holm oaks, olives, citrus trees and such.

Birdlife
Birds of the Sierra Gredos, by David Tomlinson

The Sierra Gredos is an exceptional area for birds, and many interesting and unusual species can be seen here. Most obvious are the birds of prey: look out for black vultures (buitre negro), one of the largest and heaviest flying birds in the world, with a wingspan of up to 285cm. Black vultures are rare birds in Europe, and the Gredos is one of their most important strongholds. Much more numerous than the black vulture and almost as big is the griffon vulture (buitre leonado). The two species can often be seen soaring together. The griffon is a colonial, cliff-nesting species, but the black vulture nests in trees.

Several species of eagles can be found in the Gredos, including the golden (aguila real), the short-toed (aguila culebrera) and the booted (aguila calzada). The short-toed is a large, snake-eating eagle that is a summer visitor to Spain, as is the booted eagle. This is a small, buzzard-sized eagle, and is generally quite common. Two of the most conspicuous birds of prey are the red kite and the black kite (milano real and milano negro). They are extremely graceful fliers, and are often quite tame and approachable.

The most characteristic birds of the pine forests of the Gredos are the firecrest (reyezuelo listado), the crested tit (herrerillo capuchino) and the crossbill (piquituerto comun), while one of the special birds to look out for is the citril finch (verdecillo serrano). The citril finch is a highly localised bird, found exclusively in Europe. It likes alpine meadows.

Another speciality of the Gredos is the strikingly colourful bluethroat (pechiazul). The bluethroats that nest in the Gredos are the most southerly in Europe, as well as the most westerly. They are best looked for on dry, stony slopes densely covered in Spanish broom. The cock is the size and shape of a robin (petirrojo), but is easy to identify thanks to his distinctive blue-throat with central white spot.
In spring, one of the noisiest birds of the Gredos is the nightingale (ruiseñor comun), which can be heard singing where ever there is suitable habitat. Nightingales like dense, damp habitat, preferably by the side of streams or in hedges. The nightingale is a member of the thrush family, and so is related to the rock thrush (roquero rojo), one of the most handsome birds of the mountains. This species is a scarce summer visitor to the Gredos, but is well worth looking for.

Several of the villages in the Gredos have pairs of white storks (cigueña blanca), often nesting on the village church. They are numerous in the Extremadura, and they are usually tame and confiding, drawing attention to themselves with their noisy beak clapping.

David Tomlinson is a British ornithologist, and is the co-author of the Birds of Iberia. He has visited the Gredos several times.