By KEVIN BEGOSPITTSBURGH (AP) â¿¿ Hawks swoop in and gobble up songbirds. Raccoons feast on nests of eggs they never could have reached before. Salamanders and wildflowers fade away, crowded out by invasive plants that are altering the soil they need to thrive. Like a once-quiet neighborhood cut up by an expressway and laced with off ramps, northeastern forests are changing because of the pipelines crisscrossing them amid the region's gas drilling boom, experts say. Environmentalists have loudly worried that hydraulic fracturing, or fracking, may threaten water and air, though the Obama administration and many state regulators say the practice is safe when done properly. Threats to wildlife have flown largely under the radar. But as studies detail plans for thousands of miles of new pipelines and related infrastructure, the dangers to biologically rich forests that have rebounded since vast clear-cutting in the 1800s are taking on new urgency. "If you wanted to create a perfect storm for biological invasion, you would do what the energy companies are doing in north-central Pennsylvania," said Kevin Heatley, an ecologist with the national firm Biohabitats who works to restore areas that have been damaged by human activity. "You can only put so many bloody parking lots in the woods." Energy companies, which say they are being responsible stewards of the land, have rushed to unlock the natural gas lying in the shale beneath Pennsylvania, Ohio and West Virginia. The gas has lowered energy costs, allowed the U.S. to lessen reliance on foreign energy and provided private landowners who sit atop well sites with a gold mine in royalties. New York, which also has large reserves, is trying to decide whether to allow fracking. To get the gas to market, hundreds of miles of pipeline are being laid along clear-cut forest "tunnels" sometimes dozens of yards wide.