One of the great eBird tools that I enjoy using is the distribution maps by species which I have blogged about before. These maps are also important to science to track species range; whether they are increasing or decreasing.
What better example than that of the Eurasian Collared-Dove! Introduced into the Bahamas in the 1970's and spreading to Florida in 1982, it appears that the population reached that critical mass and shot up and expanded exponentially. Check out the animated progression of Eurasian Collared-Dove expansion from 2000 through 2010 using your eBird sightings:
Here is another graph that eBird can spit out which shows that Eurasian Collared-Doves were reported about 2% of the time in 2005 and by 2009 they were being reported up to 5% of time.
I am certain studies are underway to show if this rapidly expanding species is negatively impacting other species or not. Can a species expand and compete for food without some effect on other species?