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Bat colonies choose Endesa

The Endesabats project aims to conserve the bats that live in the roof spaces of the hydroelectric plants.

 Bats in the sky coming out of a cave

Bat conservation (chiroptera) is an outstanding issue in Spain and a topic is arousing interest in Europe. Their troublesome decline and their ecological importance as a bioindicator of the healthiness of ecosystems, as well as their work at reducing plagues and regulating insect populations make it a mammal of great importance that should be protected, in accordance with the IUCN (International Union for Conservation of Nature).

32 chiroptera species have been found breeding, hibernating or being reproduced. All these species are included in the Spanish List of Wild Species with Special Protection: twelve are considered to be vulnerable, and one (Myotis capaccinii) is endangered. Fourteen of them are classified within the Habitats Directive (43/92/CEE); eleven in Annex II (species of Community Interest) and the remaining three in Annex IV (Species of Community Interest that require strict protection).

Tunnels in hydroelectric power stations are typical bat habitats due to their combination of darkness, quiet, humidity and even temperatures in winter and summer. Bat colonies have been found in Endesa facilities on many occasions, particularly in side tunnels or access tunnels to gates. In some cases, the type of tunnel closure makes it hard for them to get in and breed. This situation it is improving by suiting them to make them perfectly compatible with the infrastructure management.  

With the Endesabats Project, and working with experts from the Laboratorio de Biodiversidad y Conservación Animal del Centre Tencològic Forestal de Catalunya (Biodiversity and Animal Conservation Laboratory at the Catalan Forestry Technology Centre), we aim to gain more knowledge and improve conservation of cave-dwelling bats, their ecological requirements and how they affect hydroelectric power station operations. We also want to emphasise the importance of these infrastructures for endangered chiroptera species, and to propose management measures to help their conservation and their presence in this type of facilities as well.

Image of a bat

The study is being developed in different phases:

  • In 2013 and 2014, we studied bat populations living in the power stations and in infrastructures on the high river sections.
  • In 2015, the study focussed on the mid sections of the basins in Noguera Pallaresa, Noguera Ribagorzana and Valle de Arán: we inspected the shelters, counted the populations and characterised individuals.
  • The same year, 918 bats were captured from 11 different species, of which four were considered vulnerable and one (66% of those captured) endangered (M. capaccinii), according to the Spanish Catalogue of Threatened Species. In addition, we realised that more than 60% of the tunnels studied had been inhabited at one point by bats.
  • In October, we discovered a significant chiroptera colony in one of the tunnels at the Camarasa power station (Lleida) with approximately 400 individuals of M. Capaccinii, and roughly 200 individuals of the Miniopterus shreibersii species, all considered vulnerable.
  • In subsequent years, the Endesabats project continued to focus on the study of facilities located in the lower reaches of the river and on monitoring the most important colonies discovered in previous years.
  • During 2019, we continued with the sampling to expand the information on the bats at our facilities. The population of bats in central Galicia was studied and the population dynamics of the colonies of the Long-Fingered Bat (Myotis capaccinii) and their movements between areas in the Mequinenza area have continued to be studied.
  • In this same year, 1,190 bats of 13 different species were captured at 4 locations (3 in Galicia and 1 in Catalonia). 4 female Long-Fingered Bats were tagged with emitters to study their hunting areas and find other breeding colonies on the Ebro and Segre rivers, thanks to which a large breeding colony of 1,000 individuals was located in an old mine in the municipality of Serós.
  • In the 8 facilities of the company studied in Galicia (Campañana, Peñarrubia, Eume, Quereño, Ventureira, Ribeira, Bárcena and Cornatel) more than 15 bat species have been found and identified by the capture of individuals and ultrasound recordings.


These years of study and data compilation, at Endesa we have come up with some ideas to adapt our hydraulic facilities and being able to promote bat colonies, among the measures adopted are: changing the tunnel entrances, fitting specific refuge boxes and reducing light levels in certain critical points for the chiroptera.

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