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martes, 27 de octubre 2020
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Unexpected visitors: Wildlife in the city

by Natalia Piedrahita - Journalist
Translation by José López

Crab-eating fox (Cerdocyon thous) sighted in northern Bogotá, Colombia. Photograph: Gerardo Barreto

During COVID-19 lockdowns, sightings of dolphins have been reported in several coastal areas of Colombia.  Foxes, opossums and anteaters have also been seen prowling along the empty roads in some departments of the Colombian Andean region.

It is a scene repeated throughout the world. Seals walking through the streets of the urban center of Galapagos, Ecuador. Also, thousands of deer have been seen passing through the city of Nara, Japan. And after an absence of more than 100 years, the American bison runs again in the plains of Coahuila, Mexico. The unexpected appearance of wildlife in the cities has resulted in hundreds of memes and fake news flooding social networks, such as those viral images of dolphins and swans “returning” to the canals of Venice.

Dolphins spotted in the coastal town of Dibulla, Guajira, northern Colombia

However, other more shocking reports are true. Endangered animals such as the white dolphin and the snow leopard are returning to their natural habitats. The collateral effect of confinement during the COVID-19 pandemic is overwhelming. Animals are rewilding not only our cities but also the coasts, due to the evident improvement in the quality of the water, which has led to an increase in the presence of species that had moved to other places due to contamination and human intervention.

"Several studies have shown that urban sprawl promotes favorable conditions for groups of opportunistic species that affect the natural habitats of other species, which are forced to adapt or even migrate to other sites," says José M. Riascos, PhD in Natural Sciences and professor at the UdeA Marine Science Research Facility. According to Dr. Riascos, this may be associated with human consumption patterns that pose a threat to the survival of other species, especially those living near cities.

Noise pollution and climate change

Vehicle traffic is responsible for a large part of wildlife mortality, as in the case of tigrillos and opossums. Therefore, the decrease in traffic promotes the survival of species that live in or visit the cities. “Wild animals are exploring the habitats that urban sprawl has taken from them,” says Dr. Riascos.

"Although some animals are capable of adapting to the noise of the cities - such as pigeons, rats, and some reptiles - many others do not succeed because they rely on echolocation", says biologist Marcela Jojoa. This is the case of several groups of mammals, such as bats, that can detect ultrasound frequencies, allowing them to detect obstacles in flight and forage for food.

Many bird species use singing to communicate with their chicks and attract mates, therefore, any alteration of the acoustic environment of their habitats could seriously affect bird niches. Some studies show that noise pollution can reduce biodiversity, and although some bird species manage to adapt, this generally leads to energetic wear. The impact is greater in aquatic environments, since sounds travel faster through water.

City noise also causes stress in other species such as amphibians. UdeA professor and herpetologist Mauricio Rivera says the natural environment of many species can be altered when they move to the cities, which also leads to alteration of the trophic network and species interactions.

For example, male frogs produce vibrational signals to attract females so that they can mate. However, if they cannot counteract the noise of vehicular traffic, the male has to compete strongly with the acoustic environment so that its sounds are fairly perceived by the female. If the male fails to attract the female this would make mating difficult, thus affecting the maintenance of natural populations.

Another major problem is deforestation, which affects all organisms. In the case of amphibians, one of world's most threatened species, this has disastrous effects. At present, frogs are threatened by the pandemic caused by the fungus Batrachochytrium dendrobatidis, which is responsible for Amphibian chytridiomycosis, a disease affecting amphibians that is closely related to human intervention.

The human footprint threats

Fernando Parra, a researcher at the UdeA Marine Science Research Facility says the arrival of wildlife in the cities has a lot to do with the fact that COVID-19 confinement makes it safer for them to move through spaces that were previously dangerous. "All animals protect their young from danger, but human intervention forces them to live in such tight spaces that they usually have to share their habitats with predators," he said.

Factors such as mining and the contamination of water by pesticides and plastic, have greatly affected the lives of some species that have more particular ecological requirements since human intervention exceed the equilibrium threshold, which leads them to abandon their natural habits.

Consumption habits account for only a small part of the effects of human activities on wildlife. Dr. Parra affirms that human intervention impacts ecosystems in such a way that international protocols no longer aim to leave something behind for the new generations but to their survival.

The current pandemic will not be the last emergency situation for human kind, therefore we must ask ourselves: what are we talking about when it comes to progress? Discrimination towards ourselves and other species share the same origin, so this must be analyzed in depth in order to lower inequality and promote sustainable consumption patterns.

"Although human kind is not the only species that inhabits the planet, we have taken it for granted that we manage everything, but nature makes its way in unpredictable and sometimes unwanted ways," Riascos said.

Opossum with its young strolling through the streets of Neiva, Colombia.

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