Diego Alves and Angeles Mora are not entomologists, nor environmental experts, nor do they know anything about pest control. He is a crane operator and she has an aesthetic cabinet, but both enjoy a great capacity for practical observation of nature and an altruistic spirit. They had always been concerned with picking up disoriented swifts, unable to find holes to nest in the new urban architecture. As they did not want to limit themselves to feeding them, Alves realized their desire to fly very high and built on the plot of his farm in Brenes (Seville) a structure about 11 meters high on which he placed a kind of booth so that they could gestate. "Little by little, other species of small birds arrived, and then bats. And we found that in the afternoon we did not have mosquitoes around our house because these animals devour them," explains Alves about an insect that invades every summer the municipalities adjacent to the Guadalquivir, like his.
That particular watchtower, erected only for the purpose of relieving the stress of swifts and ensuring them shelter, has served as the prototype of the Biodiversity Tower. It is a pioneering structure that has just been installed in Coria del Río with the purpose of reducing the population of mosquitoes and removing the bitter memory of the deadly bites that in recent years ended the lives of several residents of the towns around the Guadalquivir, infected by the Nile virus of which these insects are carriers. It was the images of the structure that Mora uploaded to his Instagram that caught the attention of a Coriano friend who told the mayor. And Modesto González, the councilman, didn't think twice. He showed up at the couple's farm to see if it was feasible to implement it in a public setting.
A bird inside a tower built by Diego Alves on his plot. Paco bridges
That happened in 2021 and this Monday the new tower, this one 12 meters high, has just been installed in the Adolfo Cantalejo de Coria Park. "We have acted as the patrons of an aspiration that they had and taking into account the work that we had tried to carry out to biologically combat mosquito plagues. We felt that we had to extrapolate his idea," explains González. From there, a team of engineers technically assisted Alves —who is the one who has personally built the new facility— so that he also had the necessary authorizations and approvals to be able to place it in a municipality.
"When I visited his farm I fell in love instantly," explains Iván Casero, the forestry engineer who has endowed with technical parameters the ability to observe the nature of Alves and Mora, who have given their pilot tower altruistically for the benefit of all the residents of Coria. It is an installation "based on everything they have been contemplating and testing on their farm," he abounds. "If the inclination of the holes for birds to enter is 45 degrees, it is because they have been checking over the years that it is the slope necessary for them to nest," he gives as an example.
Alves has even thought about the psychology of birds when designing this nest tower. "It is very important that the sparrows nest first, and it is the simplest because they are small and if they enter, that gives confidence to the rest of the birds so that they decide to nest," says Alves, drawing on his experience with his particular pilot structure. "It has a hexagonal shape so that there is more surface to nest and the holes are of different sizes so that each of the birds can enter," explains the crane operator. The intention is to attract sparrows, starlings and swifts, which by their characteristics, since they usually do everything flying, until sleeping, are the ones that will be urged in the highest part. The bats will be placed in the bottom of this particular Rúe del Percebe for winged animals. "I've looked at the beehives and also what the houses were like before, where swifts nested in the high hollows," says Alves. The top is pointed to prevent eagles and other raptors from landing that can scare away other smaller birds.
This new house in Coria has the capacity to house up to 300 specimens of sparrows, starlings and swifts, all insectivores, and another 300 bats, which also include mosquitoes in their diet, with the capacity to swallow an average of one million a day. Around the tower will be planted native flora and other elements to attract reptiles, such as lizards and geckos, which also feed on insects, and protect the structure from the presence of cats or other predatory animals that may deter birds from living there. "Now we need to finish the landscaping and place the signage," says Casero.
Diego Álves, next to the tower he built on his plot. PACO PUENTES
With the expertise of Alves and Mora, coined after so much observing the environment, the technical help of engineers and municipal tutelage, this new tool has been forged to fight mosquito pests that, as the councilor says, "enhances biodiversity from the environmental point of view, public health, but also economic."
And it is that in Coria its 30,714 neighbors are accustomed to dealing with mosquitoes and the chemical effluvia of the products with which they fumigate the area every summer to prevent their proliferation. Since the appearance of the West Nile virus, these fumigations have multiplied, and not only on land. They are also carried out from the air, through drones enabled by the Junta de Andalucía. "The expenditure on fumigation in the last three years has been 200,000 euros, that of the tower 30,000," says the mayor, aware, however, that to end the problem is not enough with a single one.
"The arrival of starlings is a good biological solution, but their installation is slow and if the mosquito population is very large, there is no choice but to act in the waters with treatments that eliminate the larvae directly or introduce fish that can withstand less oxygenated waters such as those of the Guadalquivir, "warns Felipe Pascual, Professor of the Department of Zoology of the University of Granada and specialist in pest and disease control.
In Coria they are aware that this is a long-term pilot project, but they are excited to be able to advance in sustainable solutions, alternatives to pesticides, to be able to end mosquito pests. "The intention is that the rest of the municipalities join this initiative," says the mayor. "This is an exemplary pilot project for those who want to adapt it in another municipality, in a school ... They already have the technical information so that they can replicate it each one according to their possibilities, "says the engineer of Montes.
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