Javier Rodrigo
Pamplona (EFE).- Hibernating bats, after spending the winter dormant in trees, caves and fissures in many towns in Navarra, are waking up in the months of March and April and the females prepare to ovulate to have a young that will be born in June or July. So… don’t bother them.
The biologist Juan Tomás Alcalde, president of the Spanish Association for the Conservation and Study of Bats, is working these days to review the wooden boxes installed in Pamplona to sample the specimens that still remain in them.
On one of his walks, while inserting a small camera through the entrance holes of the boxes, he explained to EFE that in Navarra there are 27 species of bats, each with its different way of life and different types of shelters.
three types of bats
Experts distinguish three types of bats: cavemen, which are those that live in caves; the arboreal ones, who take refuge in tree holes, often in woodpecker nests; and fissures, which enter cracks in rocks, but also cracks in buildings and other constructions.
“In Navarra there are all three types. We have a good representation for how small the region is, we have many species”, highlighted Alcalde.
Bats are distributed throughout the entire territory of Navarra, but the most diverse area is the north, since “in the south, where agriculture is more intensive and the populations have used the land more, they have less diversity of species.”
Fisuricolous bats are the most frequent and also “they have been favored by humans, because we have made many houses, and among the tiles and stones they find a lot of shelter, with which they have adapted well to the human environment and are very frequent”, has commented.
Alcalde has highlighted that the arboreal bats are the least known bats of the three groups, “because it is difficult to locate their refuges and they also depend a lot on forest management of the forests. There are many forests in which we do not let the trees grow old and find no refuge. They depend on the presence of old trees and that they are also abundant, because very few specimens of the colony fit in each tree”.
For this reason, he has stressed that old trees and dead trees that are still standing “are extremely valuable for bats and for other species of vertebrates and invertebrates. They should be preserved, because they are vital”.
An endangered species
But not only the lack of shelters is threatening bats, since some infrastructures are causing high mortality. For example, it is estimated that in Spain between 300,000 and 400,000 bats die each year in wind farms, the Mayor said.
In Navarra, the medium-sized Night-winged Bat (Nyctalus noctula) stands out for its vulnerability, a medium-large migratory arboreal bat, with a wingspan of almost 40 centimeters, which is very rare throughout the Iberian Peninsula.
In Pamplona, he pointed out, “we have an interesting colony that is located in several parks. At a regional level, it is considered in danger of extinction, because its number has decreased in recent years, mainly due to the disappearance of trees with cavities.
Visitors to the natural environment can also inadvertently cause damage to bat colonies. In fact, there are already many caves that are closed to the public during certain times of the year so as not to disturb the bats during the periods when they are most vulnerable.
“Anyone who enters a cave and sees a bat, the logical thing to do is take a look at it, leave it alone with its rest and try to disturb them as little as possible, because bat populations are very fragile, they reproduce very slowly, only one baby per female and year, and their populations have recently declined due to human actions”, lamented the biologist.
A unique colony in Navarra
For this reason, in Navarra, the Environmental Nursery is monitoring the only known wintering colony of Miniopterus schreibersii in the community, made up of specimens that come from different parts of the Peninsula and France.
Mayor explained that this “is a relatively large colony, about two thousand specimens, which takes refuge in a cave that is rarely visited at the moment, and that saves them. We cannot say the name because it is convenient for her to remain calm.
The inconvenience to this “particularly valuable and fragile” refuge in Navarre, said the biologist, “must be minimal so that the bats can hibernate for more or less four months.”
You have to change your bad image
The mayor has recognized that bats have a bad press: “It is a cultural issue. In our culture we have always associated the dark, the nocturnal, with the dangerous. People normally don’t see the bat up close, they see a black spot flying and it’s already a bit embarrassing because of the unknown”. It is something that does not happen, for example, in Chinese culture, where seeing bats has traditionally been considered something positive and a reason for joy.
“Here we have to change the image, because bats are not really dangerous, they are not harmful, on the contrary, they feed on insects and their impact on the environment and on our interests is very good, because they take away pests and even mosquitoes that they can bite and transmit diseases, so their effect is very positive”, indicated Alcalde.