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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 that should be protected, in accordance with the IUCN (International Union for Conservation of Nature).

32 chiroptera species have been found breeding, hibernating or mating in Spain. 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 can be improved 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 phases:

  • In 2013 and 2014, we studied bat populations living in the power stations and in infrastructures on the high river sections.
  • In 2015, we 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.
  • The Endesabats project continued in 2016, focussing on studying facilities located in low river sections and on monitoring the most significant colonies discovered in previous years. 


After more than three years of study and data compilation, at Endesa we have come up with some ideas to adapt our hydraulic facilities including changing the tunnel entrances, fitting specific refuge boxes and reducing light levels in certain critical points for the chiroptera.