Ornithologists and conservationists have for years feared that invasive alien species from across Asia have been displacing local birds. New research conducted at Technion – Israel Institute of Technology and published on Tuesday has confirmed these fears using newly available quantitative data.
The study shows invasive species have expanded exponentially over the past two decades while local species declined. The researchers believe the locals are losing the fight over limited natural resources. Previous research documented invasive species taking over local nests in Tel Aviv’s Yarkon Park, for example. Now they fear other local species could be endangered.
The researchers tracked changes in communities and populations of common birds over several years using data from Yarkon Park and Ramat Hanadiv. They also used an annual winter survey data “collected by citizens jointly organized by the Israeli center for Yardbirds and the Birding Center of the Society for the Protection of Nature.”
The findings of the study, funded by the Israeli Science Foundation, reveal that the local bird population is declining across Israel, especially in urban areas where invasive species like the common myna and the rose-ringed parakeet have flourished.
Until recent decades, certain local species had managed to adapt to Israel’s accelerating urbanization and had begun to flourish in urban areas, mainly the house sparrow, the white-spectacled bulbul and the Eurasian hoopoe. However, the research shows that these adaptive species are declining in number, while the number of invasive species is rising sharply. The myna population soared 843 percent over the past 15 years, while the rose-ringed parakeet population jumped 250 percent.
The research also shows that it’s nearly impossible to spot any of the local species where they once thrived in Tel Aviv’s Yarkon Park, where many of the invasive species were introduced at the end of the 20th century. “Nearly two decades ago, we began researching the impact of invasive bird species on local birds,” says Shwartz. “Regretfully, the current research indicates that our forecasts regarding the pushing out of species has become reality. I fear that my children won’t be able to see and hear the sparrows, the honey-suckers and the bulbuls, some of the most common birds in Israel today.”
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The research findings did show that the invasive species have yet to establish a significant presence in areas of nature reserves, like in the Galilee. However, the researchers fear that they will succeed over time to penetrate these areas as well.
Ornithologists and conservation groups now propose taking steps to retard the spread of the foreign species, such as making artificial nests that imitate in size those of local species. Another one is preventing as much as possible the spread of food-based litter. In certain circumstances, the nature organizations assert, there will be a need to shoot birds as well in order to thin out the species that are growing at a significantly faster rate.