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Exotic bird migrations are changing the world

Exotic bird migrations are changing the world

Not all species survived these changes. Those that have prospered, Professor Blackburn noted, were those that moved to more biologically diverse areas, which are already rich in native bird species.

"More than half of all known bird introductions were determined after 1950, likely driven by the caged bird trade, and the researchers say this trend is expected to continue," the researcher noted.

Not all species survived these changes. Those that have prospered, Professor Blackburn noted, were those that moved to more biologically diverse areas, which are already rich in native bird species.


“We have been mapping the richness of exotic species for a whole group of organisms for the first time in such detail that we can locate the populations and historical processes that led to their introduction. We have been given valuable information about the different stages of invasive species - humans play a fundamental role, but so do other environmental factors that allow these species to thrive in their new places, ”said the academic.

Considering the movement of birds observed by international biologists of more than a thousand species between the years 1500 and 2000, it was revealed that, for example, in only 17 years between 1983 and 2000, 935 introductions of 324 species were made to 235 countries. The figure for this period is much higher than the records recorded between 1500 and 1903, which total 403 years.


In fact, more than half of all known bird introductions of the past 500 years occurred after 1950, "primarily through colonialism and the increasingly popular trade in cage birds," the document says.

According to Professor Tim Blackburn, by moving these species to new areas where they normally do not reproduce, "humans are altering the world." The danger, should trade increase in the coming years, is that "these exotic species could endanger the survival of native species."

The rate of introductions increased sharply in the middle of the 19th century, with the transfer of Europeans, "especially the British," who "exported 'beneficial' birds to new territories (...) such as ducks, geese, pheasants, partridges and pigeons."

Another acceleration that occurred after World War II, and continues to increase to this day, is likely driven by the growth in the trade in popular cage birds - including parrots, finches, and starlings.

"In many areas, owning a foreign bird was a status symbol, and sometimes these species escape or are released," says the scientist.

The world map of exotic birds in turn shows that today most species are found in the middle latitudes, "where the former British colonies and the countries with the highest Gross Domestic Product are."

Among the countries with the highest income from these birds are the US, Japan, Taiwan, Hong Kong, New Zealand, Australia and the Persian Gulf States.

In turn, the research emerges that the areas richest in diversity of native species, that is, with greater biodiversity, are those that have allowed the survival of the exotic ones.


"The term 'the rich get richer'" certainly applies here as well, Professor Blackburn noted. “Areas that are also good for native birds are good for exotic birds. This is not a new observation, but it is the first time that we have been recording the effects of historical human actions that have been key ”.

The research published in the journal de Plos biology also included members of the University of Adelaide, the University of Cambridge, the University of Exeter, the University of Queensland, and Imperial College London.

The Epoch Times


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