The analysis of the migrations of birds in the Strait of Gibraltar will allow scientists to advise administrations and companies for the installation of electric power wind turbines and that these do not interfere with the birds' habits. On their return trip this year, researchers have also studied the effects of human absence from confinement on flying fauna.
A team of scientists, led by researchers from the University of Malaga (UMA), has analyzed the trajectory and movement patterns of birds when crossing the Strait of Gibraltar. The aim is to advise the administrations and companies for the correct installation of wind turbines without these interfering in the habits of the different birds that cross the area.
The project began in 2018 with the aim of finding a way to minimize the ecological damage that windmills cause to flying fauna. Wind turbines often force birds to change their routes, or make their movements more expensive, in terms of energy. In their latest analysis, which has coincided with the period of confinement due to the COVID-19 pandemic, the scientists will also address the impact of human quarantine on the hundreds of birds that have crossed the Strait.
“This isolation will offer us a unique opportunity to study animal behavior and it will be very interesting.”, Comments Antonio Román Muñoz, professor of the Department of Animal Biology of the Faculty of Sciences of the UMA Antonio Román Muñoz, one of the main authors of this work, which has been published by the scientific journalJournal of Animal Ecology.
The expert maintains that, so far, it is not known that birds perceive the urban environment in the same way as humans, so they will investigate if there is any change. "Everything that happens will be significant, since the pollution and noise conditions, among others, have changed, and this could lead them to modify their routes in the face of the new situation.”, He emphasizes.
The researchers analyzed the flight behavior of 73 black kites (Milvus migrans) during the crossing of the Strait of Gibraltar, on its way to wintering grounds in sub-Saharan Africa. "We have chosen these specimens because, thanks to their size, they can easily carry a GPS that we have created with which to analyze their routes”, Explains the UMA expert.
This device has been designed by the scientific team itself and is one of the most accurate on a world scale, as it can report the location of each of the marked specimens every second, and even know precisely how many flaps the birds need to take the tour.
To analyze the way of flying, an accelerometer of the same type that mobile phones have was also incorporated, with which the steps taken or the screen rotated when the orientation changes are counted. "For us it was crucial to know how they made the route, how they planned their crossing based on the environmental conditions, if they planned, how many times they beat their wings per second and if there were differences between the adult and juvenile specimens”Says Román Muñoz.
A strategic route
Thanks to this study they have been able to determine the procedure of the birds to cross the Strait. According to the researcher, although it is a route with a minimum distance of 14 kilometers, they rarely use it, since they are displaced by the strong winds that usually exist in the area.
“We have observed that kites strategically prepare for this journey and do not cross instinctively. For example, adult specimens, which have already crossed previously, do so in a more efficient way, using the prevailing wind at the time as an aid, while young specimens need several attempts when crossing alone or accompanied by adults. that guide them to do it properly”, Clarifies Román Muñoz, who emphasizes that crossing this small step is crucial for these animals.
“It must be taken into account that the thermal currents from which these birds benefit to move with reduced energy consumption are generated only on land, so that in the open sea the flight is very expensive and they must optimize their effort, in addition to not they can rest on this journey”, Assures the teacher.
“For this reason they tend to choose the shortest area through which to make the trip, which would be very difficult if the distance was greater. This choice of favorable routes and times suggests complex brain reasoning", Add.
In addition to the kites, other birds such as storks, other raptors and bats use this path to change continents at different times of the year. The neighboring area of Tarifa is also known for the abundance of days with strong winds, making it one of the areas with the most wind power stations and with the greatest potential for the development of this energy.
“This study allows us to detect points of very frequent use by birds, so that these sites are not used by wind farms to install turbines, since in the same wind farm we can find wind turbines that cause high mortality nearby of some that are practically innocuous”, Highlights the researcher.
“Having machines in a park that affect birds and bats is also a problem for energy companies, as they are forced to hire machine shutdown services”, He concludes.
Antonio Román Muñoz, Carlos Daviz Santos, Joao Paulo Silva, Alejandro Onrubia and Martin Wikelski. "The gateway to Africa: What determines sea crossing performance of migratory soaring bird at the Strait of Gibraltar?"Journal of Animal Ecology, 2020 https://doi.org/10.1111/1365-2656.13201