From PBS.ORG
In anew study published Tuesday in PLOS ONE, a group of researchers analyzed one of the rare data sets that tracks butterfly abundance, taken from 21 years of volunteer surveys in Ohio. They found an average population decline of 2 percent per year, which means that over the course of the study, Ohio lost more than a third of its butterfly population.
Some species of butterflies showed no change in abundance, however, and a few others actually became more common.
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