One of Spain's last untouched landscapes, the Sierra de Gata in north-western Extremadura, may shortly be inundated with up to 91 wind farms.

Ecologists are increasingly concerned about the impact these "parques eólicos" may have on the varied wildlife of the region - and, not least, on its pristine landscapes. Currently, Extremadura is popular with nature tourists, particularly walkers and birdwatchers from all over Europe.

For centuries this region was so off the beaten track that many people in the Spanish cities had never heard of it. Now the Sierra is waking up to the 21st century, and it threatens to be a rude awakening.

Wind power is currently de rigueur in Spain. Major wind-power schemes have appeared in Navarre, Aragon, Galicia and Andalucía. Now is the turn of Extremadura, the western region bordering Portugal, where a total of 91 wind farms are planned.

The final list of approved projects is to be published this summer and the schemes will be on stream by 2010, according to the regional Junta de Extremadura.

The Sierra de Santa Olalla, a sub-range of the Sierra de Gata, is a prime site for the projected wind farms, with five companies competing to erect as many as 25 windmills along its length. The mills, which are 130m in height, will dwarf this chain of low hills carpeted in oak and chestnut woods, where the only visible buildings are shepherds' huts and dry stone walls. Inexplicably, Santa Olalla enjoys no protection under Spanish law.

Locals in the nearby villages of Hoyos and Cilleros are puzzled by these developments, pointing out that the area has relatively little wind. Others simply repeat what most extremeños already know - that Extremadura is already more than self-sufficient in energy, and anything produced by the wind farms in Sierra de Gata will immediately be "exported" to the power-hungry cities of Madrid and Barcelona.

Traditionally dependent on agriculture, and supported largely by generous grants from Brussels, Extremadura must now look for alternative sources of revenue. One idea is to use its greatest resource - unpopulated landscapes and biodiversity - to attract green-minded tourists.

This strategy seems to be working, not least in the Sierra de Gata, where a new breed of casas rurales (hotels in working farms) are proving popular with birdwatchers, walkers and amateur naturalists. The new wind farms, which will be seen and heard for miles, may well prove a major setback for the region's nascent tourist industry.

Miguel Muriel, of the Casa Rural Finca el Cabezo, believes his business will suffer, and accuses local politicians of "selling the Sierra de Gata for a few crumbs of bread".

The wind farms are especially worrying for ornithologists, who see Extremadura as one of Europe's most important refuges for bird life. The Spanish Ornithological Society includes the Sierra de Gata among its "important areas for birds", citing rare species such as the Black Stork, Egyptian Vulture, and the most endangered bird of prey in Europe, the Imperial Eagle.

Wind farms are notorious killing grounds for birds, which can easily fall victim to the mills' 45m blades. Recent figures from Navarra reveal that 7255 birds (including 409 vultures and 432 birds of prey) were killed in 11 wind farms over a 12-month period.

The process of authorizing Extremadura's wind farms has been clouded in confusion, with scarce information and little public debate at a regional level. Local pressure groups have accused the Junta de Extremadura of a lack of transparency in the authorization process. There is money in wind-power, that much is certain, as Spain rushes to fulfil its EU quota on sustainable energy. But how much money, and who exactly is receiving it, are not quite so clear.

As the deadline approaches (June 23) for the public to submit objections to the scheme, local wits are recalling the famous lines from Spain's greatest novel, Cervantes' Don Quixote:

"Take care, your worship", said Sancho; "those things over there are not giants but windmills..."

"It is quite clear", replied Don Quixote, "that you are not experienced in this matter of adventures. They are giants, and if you are afraid, go away and say your prayers."