Currently there is a campaign to eradicate the European Starling from North America because of its threat to other species. Are there actual data regarding the extent of the ecological risk to native species, and are there data on the effects of the current eradication programs (are they working)?
In North America, there an estimated 140 million European Starlings, or about 45% of the global total. The species was introduced to the continent over 100 years ago when only 120 or so were released in the New York area. Those few have quickly spread across the whole continent, competing easily with other native birds of similar type, especially for nesting holes, because they are naturally far more aggressive. It is currently listed in the IUCN List of the world's 100 worst invasive species. Annually, the US kills over 1 million of them with the sole purpose being extermination. There is even a specific poison commercially available. However I am having difficulty finding data to show how invasive the Starling really is in North America and the extent of the ecological risk to native species because of their presence. I would also be interested in data showing the impact of current control methods (do they actually reduce the impact on native species?).