Wind is one of the older sources of energy used by people. About five thousand years ago, people in the Middle East used wind energy to propel their boats, and from these primitive machines, mechanical devices able to transform wind energy into more friendly energy forms have been continuously developed and improved, the most conspicuous example probably being the windmills used to drive grain-grounding wheels, or drainage pumps. Windmills were developed as early as the Seventh Century by Moslems, and they spread to Europe following the Crusades.
Windmills have been part of the landscape for centuries around the world, and it seems they have been at equilibrium with life existing in their surroundings. Probably such equilibrium was reached in a natural way, because old windmill designs were strongly limited by both scientific and technological constraints, and this situation has been kept unaltered (in an historical frame of time) until very recently, when technological improvements based on both new-materials development and a deep knowledge on wind-turbine aerodynamics have allowed the design and construction of new machines having large dimensions and high efficiency, mainly devoted to electrical power generation. The reasons for this late development can be found, as already said, in the previous lack of materials able to withstand the high loads of new designs, and in the absence of scientific knowledge on the interaction between wind and solid bodies (in particular, rotating blades).
To complete the description of the current technological situation concerning wind energy, it must be taken into account that the increase in per-capita energy consumption grows in parallel to the availability of both cheap and efficient systems of energy distribution, as it happens with electricity during the XX Century; because of that, per-capita energy consumption is nowadays one order of magnitude greater than a century ago.
The growing demand for energy, together with the feeling that our planet is an ecosystem in a very delicate equilibrium, has stressed the search for new mechanisms of energy transformation that preserve such equilibrium. Therefore, besides a huge consumption of both fossil and nuclear fuels (each of them with their advantages and drawbacks), the use of the so called renewable energies is growing spectacularly, wind energy being one of them.
Wind energy as a source for electricity generation is a relatively new application. Some three decades ago, wind-turbine technology was still in the experimental phase (although small electric wind turbines were used in rural areas of the U.S.A. as far back as the 1920´s, and prototypes of large machines were built in the 1940´s). From that time, wind energy has become the fastest growing energy source in the world.
Obviously, wind energy is not free of problems, although these are small when compared to those associated to other sources of energy. Wind turbines can negatively affect the fauna that develops in their surroundings, mainly the birds. The reason for such negative impact must be found not only in the spectacular increase of the number of turbines (for instance, there are now some five thousands large-size wind turbines installed in Spain), but in the continuous improvement in turbine design, with blades exceeding 25 m span and with very high performances. Rotating speeds are nowadays relatively high (typically some 30 rpm for a 600 kW machine), and in consequence tip blade speeds are also relatively high (a typical value is 80 m/s). Because these high velocities, birds have little or no possibility to survive after an impact with the rotating blade of a wind turbine. Other negative impacts do not affect birds directly (visual and sound impact, habitat loss) but these could be more important than direct mortality.
Because of that, in spite of the advantages of wind energy when compared with other more classical energy sources based on the consumption of either fossil or nuclear fuels, wind energy has its own drawbacks (although wind energy has been felt and still is being felt as a clean source of energy, with little negative impact). Wind turbines and associated equipment (mainly electric power lines) are a potential source of accidents for birds flying close to such machines. This negative impact may be tragic in the case of protected species with very reduced populations.
This problem is somewhat new, as large wind turbines are. The knowledge on the interaction between flying animals and wind turbines, and the solutions to potential compatibility problems, is still limited and scarce. Nowadays the use of wind energy is a goal in the energy policy of a representative number of countries, and wind energy is widely accepted as a source of energy without the almost insurmountable environmental problems appearing on other, more classical sources of energy. However the use of wind turbines has also an ecological cost which could be measured, for instance, by the number of birds dying by impact with turbine blades, beside other more aesthetical landscape impact. This cost is a matter of controversy, but there is no doubt that its reduction should be one of the targets in wind energy policy.
Reading what is published on wind energy, one may get the idea that there are two-extreme communities whose respective interests are not in agreement. One of these communities gathers people involved in wind-turbine technology and related industries (including the owners of the sites where wind turbines are placed), whereas the other community gathers people concerned with the preservation of wild life as uncontaminated by technological developments as possible. Fortunately facts are not so extreme, and although some polarization seems to exists, all partners involved are aware that an agreement between the different points of view is needed, the effort to reach such agreement being greater every day.
To minimize the negative impact of wind turbines on bird life is a formidable task that requires the conjunction of efforts coming from very different fields. First of all we need to increase our knowledge on bird aerodynamics, as well as on the behaviour of birds flying either in wild environments or close to wind turbines. We need to establish clear criteria concerning how birds use all the aerodynamic resources provided by airstreams in the atmosphere to optimise their flight paths, and all this knowledge, amongst other, must be incorporated in the design process of wind energy farms, to keep between reasonable boundaries the impact of wind turbines on birds. The agreement and the cooperation between all partners involved, mainly biologist and engineers, to face together the different aspects of this problem, increases every day, and we must spare no effort to increase even more such a collaboration. A good example in this direction is the edition of this book.
This book presents a scientific approach for the assessment of the hazard this new industry poses on bird populations. This book is coordinated by three researchers from Donana Biological Station (Spanish Research Council) and written by different scientists of international recognition from different countries. It presents an objective overview of the various technologies and their potential effects on birds and bats; methods of minimizing the risk of adverse impacts; and gaps in the actual knowledge and how to tackle them. The increasing number of wind farms around the world must be aware of the potential effects on birds and bats and get familiar with the methods of minimizing the risk of adverse impacts. The experts put a considerable emphasis on encouragement and improvement of the communication between the different interested and involved parties (wind power companies, scientists, ecologist, governments, technicians and lay people).
Introduction: From Don Quixote windmills to wind farms: a snake biting its tail - V. Penteriani (pp. 21-23)
Chapter 1: The Altamont Pass wind resource area's effects on birds: a case history - C.G. Thelander and K.S. Smallwood (pp. 25-46)
Chapter 2: Responses of birds to the wind farm at Blyth Harbour, Northumberland, UK - E.S. Lawrence, S. Painter, and B. Little (pp. 47-69)
Chapter 3: Trapped within the corridor of the Southern North Sea: the potential impact of offshore wind farms on seabirds - E.W.M. Stienen, J. Van Waeyenberge, E. Kuijken, and J. Seys (pp. 71-80)
Chapter 4: Wind turbine collision research in the United States - D. Sterner, S. Orloff, and L. Spiegel (pp. 81-100)
Chapter 5: A sampling framework for conducting studies of the influence of wind energy developments on birds and other animals - M.L. Morrison, K.C. Sinclair, and C.G. Thelander (pp. 101-115)
Chapter 6: Selecting study designs to evaluate the effect of windpower on birds - D. Strickland, W.P. Erickson, D. Young, and G. Johnson (pp. 117-136)
Chapter 7: Predicting the effects of wind farms on birds in the UK: the development of an objective assessment method - S.M. Percival (pp. 137-152)
Chapter 8: Effects of wind turbines on birds and bats in Southwestern Minnesota, U.S.A. - K.F. Higgins, R.G. Osborn, and D.E. Naugle (pp. 153-175)
Chapter 9: Avian mortality in wind power plants of Navarra (northern Spain) - J.M. Lekuona and C. Ursúa (pp. 177-192)
Chapter 10: Wind farms in the Orkney Islands, Scotland: environmental impact, past, present and future - E.R. Meek (pp. 193-199)
Chapter 11: Collision risks for diving ducks at semi-offshore wind farms in freshwater lakes: a case study - S. Dirksen, A.L. Spaans, and J. van der Winden (pp. 201-218)
Chapter 12: Wind farm effects on birds in the Strait of Gibraltar - M. de Lucas, G.F.E. Janss, and M. Ferrer (pp. 219-227)
Chapter 13: Spatiotemporal patterns of bird mortality at two wind farms of southern Spain - L. Barrios and A. Rodríguez (pp. 229-239)
Chapter 14: Use of data to develop mitigation measures for wind power development impacts to birds - G.D. Johnson; M.D. Strickland; W.P. Erickson; and D.P. Young, Jr. (pp. 241-257)
Chapter 15: Developing field and analytical methods to assess avian collision risk at wind farms - W. Band, M. Madders, and D.P. Whitfield (pp. 259-275)