30.10.2026 03:04
Silver pheasants brought to an island in Argentina about 70 years ago have turned into a problem threatening the balance of nature years later. Scientists determined that the birds, whose numbers are gradually increasing, are putting pressure on the island's natural vegetation by spreading the seeds of invasive plants.
Silver pheasants of Southeast Asian origin were introduced to Victoria Island, located in Nahuel Huapi National Park in Argentina's Patagonia region, in the 1950s.
The birds adapted to their new habitat, multiplied over time, and spread to different parts of the island. However, research conducted years later revealed that this situation had unexpected consequences.
THEY THREATEN THE NATURAL BALANCE
Scientists determined that silver pheasants feed on the fruits and seeds of plants introduced to the island from outside, and then carry these seeds to different areas through their droppings. This made it easier for some plant species not naturally found on the island to spread, while also making it harder to protect the native vegetation.
STRIKING RESULTS EMERGED FROM THE RESEARCH
In a study conducted by researchers from the Argentine National Scientific and Technical Research Council (CONICET) and the National University of Comahue, it was found that silver pheasants were seen more frequently in areas with intense human activity.
While an average of 5.69 silver pheasants per hectare was recorded around the port, this number was calculated as 1.77 in areas that better preserved their natural structure.
In another study conducted with camera traps, 710 independent images of eight animal species were obtained. While species introduced to the island later made up 99.7 percent of the images, silver pheasants were recorded 222 times.
THEY WERE BROUGHT UNDER CONTROL IN 2021
Due to their possible effects on the environment, silver pheasants were classified among species subject to controlled use in Argentina in 2021. However, no decision was made to completely remove the birds from Victoria Island.
Through nature conservation efforts continued on the island, the aim is to reduce the pressure created by introduced species and strengthen native vegetation.