 That's Rick Ostfeld with the nonprofit Cary Institute of Ecosystem Studies in Millbrook, New York. He's been doing some of the longest-running surveillance of tick populations in the Northeast. Because of human-caused climate change, Vermont now sees about a week more freeze-free days than it did in the 1970s. And the growing season is getting longer every decade. Ostfeld says that makes it easier for black-legged ticks to find hosts to feed on