Due to pesticides and habitat loss, more than 50% of common birds have disappeared in the last 50 years, causing serious damage to the ecosystem
He is about to end up run over, his mother saves himIn the last half century, the number of birds present in Europe, Canada and the United States decreased by 3 billion, with one loss of specimens equal to 29%.
To show how the skies of North America, but also those of Europe are emptying are the results of an analysis published yesterday in the journal Science.
The study authors looked at the data for 529 bird species, accounting for more than 90% of the entire bird population in the area, drawing on censuses carried out in recent decades by the North American Breeding Bird Survey, the International Shorebird Survey and Audubon's Christmas Bird Count.
Scientists expected populations of rarer species to have declined over the past few decades, but that these losses were offset by the increase in common specimens. sparrows, finches, robins and blackbirds, more resistant than rare species.
In fact, the team of researchers found that 31 million adults have disappeared among the 1970 most common bird species since 700, recording a loss of specimens equal to 53%,
"When you lose a common species, the impact is much more severe on the ecosystem," said Gerardo Ceballos, an ecologist and conservation biologist at the National Autonomous University of Mexico.
Common bird species are indeed vital for ecosystems, as they control pests, pollinate flowers, spread seeds and help regenerate forests.
The loss of a sparrow does not receive the same attention as the loss of an eagle, but its impact is much greater and when these birds disappear, the whole ecosystem suffers dramatically.
The causes of the dramatic decline
Le causes of the disappearance of so many specimens at a shocking rate are different. One of the main ones is certainly the habitat loss caused by climate change and human activities, which leads to a decrease in food resources for birds.
To this is added theuse of pesticides: In fact, toxicologists have underlined how the presence of pesticides even at low doses can determine the weight loss of sparrows, delaying their migration and thus decreasing the chances of surviving and reproducing.
In addition to these, there may also be other reasons behind the disappearance of common bird species, not yet known to scientists.
What is known instead is that the flocks of birds are getting smaller and smaller and this must represent a alarm bell.
According to the study authors it could be very difficult to stop the decline of all bird species, but there is hope to stabilize populations currently existing.
In the past, significant losses were recorded among eagles and other raptors caused by the use of DDT: since the use of the insecticide was banned, the population of these birds has grown, a sign that removing the cause of the decline of a kind it is possible to stop even the decline itself ..
The decline in Europe
The disappearance of birds is not an exclusively American phenomenon: in 2014, European researchers also published comparatively similar data. In that research which began in 1980 and ended in 2010, the European bird population had been reduced by 400 million compared to an estimated 2000. In addition to the lower time range, this study was limited to 144 "common" species, but the trend is also confirmed by the latest report (with data up to 2016) of the Pan-European Plan for the Monitoring of Common Birds (PCBMS) which highlights as a third of the species are in decline.
According to the researchers, action is essential to stabilize bird populations stopping habitat loss and regulating the use of pesticides in agriculture
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Tatiana Maselli
