Every year they die in Spain between 100,000 and 200,000 bats by the blades of the wind turbines of the wind farms, as explained by the president of the Spanish Association for the Conservation and Study of Bats (SECEMU), Juan Tomás Alcalde.
In an interview, Tomás Alcalde, who is a doctor in Biological Sciences, describes as “worrying” that there are average figures between four and 11 bats killed by wind turbine and year.
The biologist, who is dedicated to studying the populations and migrations of these mammals, highlights that the low reproductive rate of the species, “around one calf a year”, is causing the population “to decline blatantly and there is no way they can replace such a high mortality.”
Tomás Alcalde also emphasizes that the monitoring of the mortality of bats and birds that is carried out in several wind farms in Spain does not reflect the “high impact” of wind turbines in fauna.
“Sometimes studies are done badly, it is said that no corpses are found, and thus it is argued that the impact is small because there are no bats “, denounces Tomás Alcalde, who also works on projects for the conservation of bat populations, placement and review of refuge boxes and studies of the impact of wind farms on these mammals.
In the last year, the association has analyzed some 140 environmental impact studies of wind farms and “less than 10 had serious studies of bats; the other 130, either do not have or have ridiculous studies,” says this specialist.
According to the president of SECEMU, the main death of bats It is caused by the impact of the blades, whose tips reach a “normal” speed of about 200 kilometers per hour with a circular motion.
“Since bats have never lived with anything moving at these speeds before, they don’t know how to calculate distances of something that goes so fast, “says Tomás Alcalde, who points out that, nevertheless, half of the bats die without the blades touching them. They die from” barotraumas “, that is, sudden pressure changes caused by the blades.
According to this expert, when autopsies are made on the corpses of bats that are collected from wind farms, about half do not have any broken bones, although they are “very delicate” animals.
Death occurs by a internal bleeding in the lungs or abdominal cavity caused by a barotrauma, caused by a very abrupt pressure change when they approach the wind turbine blades.
The third reason is that are “attracted” to wind turbines and they look around because it is “something that stands out in the landscape”, like a large tree, an element that they consider “valuable”.
For this reason, from SECEMU they ask the administration and the wind power developers to do the environmental impact studies well because now they are a “disaster with capital letters, which are very far from the European guidelines”, he denounces.
It also calls for a good monitoring of mortality, using dogs and frequently inspecting the terrain because “many times it is taken for granted that what is found is what dies and only five bats have been found, but no one has said that these represent many more that have not been found.”
You have recalled that there are currently 13 species of bats in danger of extinction, so it is necessary to apply corrective measures to reduce their mortality, especially in August, September and October, which are the months in which between 85 and 95 percent of bat deaths occur because that is when bats are in heat, with a “very frenzied activity” and a lot of hunger, because they have to store energy and fat to get through the winter.
“Only with that we we would avoid a 80 or 85% of deaths of bats, and that’s tens of thousands, “he stresses.
Based on monitoring wind farms, the association’s biologists have observed that most bats die on nights with light winds, when the wind turbine rotates “slowly”, at low speeds, between 80 and 90 kilometers per hour, “enough to cause a blow or barotrauma”.
“The measures we ask for are a very small loss of benefit for companies “, concludes Tomás.