Noise pollution in major cities is generally thought of in terms of its impacts on human health, yet it has also become a serious threat to animals and especially birds.
Even though some species have adapted to noise pollution, "many birds are affected by this noise," Jose Rafael Calderon Parra, a specialist working for the North American Bird Conservation Initiative, told EFE.
He explained that physical damage to birds' auditory systems has already been identified, adding that some species of birds have had the capacity to recover from those damages, although this only happens when certain noise levels are not exceeded.
"Some species are very sensitive to noise, they are easily frightened and are under constant stress that affects their general performance and behavior," Calderon said.
Noise frightens birds, creating stressful situations in which they fly away using energy they could have used to search for food, to rest or for other crucial activities like mating, the biologist said.
"Male birds sing to attract mates and their song determines whether they are chosen by a female bird or not," Calderon said.
Noise pollution, however, affects bird communication since they have to compete with city noise, having to emit louder and higher frequency sounds, which make them consume more energy.
Territorial birds are also affected since they use sounds to defend their territories.
In addition, many flocks of birds use sounds to stay together, although noise pollution can lead some birds to be cut off.
"Birds detect danger through sound and if they cannot hear danger coming they become vulnerable to predators," Calderon added.
In this context, city birds tend to avoid very loud areas and seek more isolated spaces.
"The more vegetation there is, the more protection against noise pollution there will be. However, if there aren't enough green areas, bird populations will not be able to recover," the specialist said.
In greater Mexico City, more than 300 species of birds can be found, Calderon explained, adding that it is important to raise awareness about the need to preserve many species.
This is why urban bird programs are being promoted in many different cities in Mexico.
"These are community science programs that include bird watching activities to bring people closer to the many species of birds living in our cities ... to recognize that these species exist and to be able to value their presence," Calderon said.