When you think about the U.S. Border Patrol using helicopters, the picture in your mind probably includes cacti, not towering pine trees. That image will have to change as the post-9/11 U.S. homeland defense initiative moves to secure all of the country’s borders, both north and south. Among the first new moves came last month in the form of an MD 500C now stationed at Houton, Maine, and tasked with patrols along the largely unsupervised expanse of the U.S./Canada border, a 3,100+- mi frontier that is the longest unfortified international boundary in the world. The MD 500C is supported by a Border Patrol Cessna 206. Maine shares more than 600 mi of border with Canada, most of it dense pine forest. The aircraft reassignment marks the first such move north of Border Patrol air assets in recent years.