The cities are “simplified forests”, an unexpected refuge for migratory birds

The cities have become authentic oasis for migratory birds, functioning as “simplified forests” that offer refuge and food, particularly insectivorous species. A recent study published in Plos Oneled by Rodrigo Pacheco-Muñoz, Adrián Ceja-Madrigal and Jorge E. Schondube, researchers at the Institute of Ecosystems Research and Sustainability of the National Autonomous University of Mexico (UNAM), explore how the communities of migratory birds in a region of the West From Mexico, highly transformed by human activity, they use urban, agricultural and natural habitats.

Migratory birds, which travel great distances every year, depend on adequate habitats to survive during winter. The study, which compared bird populations in urban, productive (agricultural) and natural environments, reveals that, although natural areas are the most beneficial, urban areas also play an important role, although often underestimated, in support to Populations of migratory birds.

The researchers carried out their study in the Bajío, a region with a long history of human impact. They conducted points in thirteen locations, each of which included urban, agricultural and natural areas. This approach allowed them to evaluate the diversity, abundance and functional features of migratory bird communities.

“The cities, which are extremely complex systems, always offer water. Humans have a lot Pacheco-Muñoz and Jorge E. Schondube, in an interview with Wired. “The cities become very important in the neotropical zone, because the neotropical zone, where our Latin American countries are located, is the most diverse area of ​​the planet … and since cities are for humans and we are the ones we use the Resources from the planet, we take from other areas to have those resources within the urban area. “

The study found that, as expected, the natural areas housed the greatest wealth of species and abundance of migratory birds. These areas provide a complex vegetation structure that supports a wide variety of species. In contrast, urban environments had the slightest wealth of species, since urbanization replaces natural habitats with constructed structures, altering the ecosystem. However, they also discovered that the urban environment has a “wasteful potential” to house communities of complex birds.

On the other hand, explain the researchers specialized in ecosystems and sustainability, even in cities there may be diverse habitats to support biodiversity: “cities can be a very bad place for biodiversity … when they are very simple cities that have very little Diversity of habitats within them … When that happens, we generally find about 60 % less diversity in the city than outside it. ”

According to the investigation, the insectivorous and granivorous birds were dominant in the three environments and the productive environments had a greater abundance of granivorous birds associated with grasslands, while the urban environments were dominated by insectivorous birds with preference for dense habitats and short peaks.

“If we add things to the city, such as a park, a football field, a public square, buildings with structures and spaces that fauna can also use, as balconies, suddenly the city becomes a place with many opportunities for the Fauna, “Rodrigo Pacheco-Muñoz and Jorge E. Schondube argue.

This discovery acquires special relevance in a critical global context, characterized by the deforestation of forests and jungles – the planet lost 4.1 billion hectares of tropical virgin forests during the last year, which is equivalent to losing 11 jungle soccer fields per minute; Aidification – 77.6 % of the planet’s earth’s surface is now drier than in the 1990s – and defaunation, which between 1970 and 2018 has caused a 69 % decrease in populations of wild animals monitored, including mammals, Birds, amphibians, reptiles and fish. On a planet that literally burns, this investigation emerges as a ray of hope.

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“Now that we are beginning to understand cities as a new system and as an ecosystem, we can give ourselves the opportunity to rethink them and begin to consider other natural elements within the cities … and we are seeing that the fact of considering them and putting them in the City not only increases biodiversity … but also promotes a better quality of life, “says biologists.

Although natural areas remain fundamental for biodiversity, research underlines the importance of preserving diverse vegetation, especially trees, in urban and agricultural landscapes to guarantee the conservation of migratory birds. Through the use of statistical models, the researchers analyzed the differences in the composition of species and the functional features between the different habitats, providing valuable perspectives for the protection of these species in a world increasingly transformed by the human being.

“There are birds that use the entire city … urban birds … and then there are additional packages of species that use these other elements of the cities … in Morelia we have some species that are not commonly seen in cities … They only use the city to reproduce, “say the investigators of the UNAM.