“Really, the inspiration behind it was getting above the sidewalk level,” Cory said. “You’re getting into your own little world and rising above the stress of the street life.”

Their first try came a few months later, in August, while visiting Williamsburg, Va., but they encountered hammock-hanging problems.

Soon, they learned the importance of selecting the right tree. It must have branches low enough to be ascended without a rope, but also have boughs high and sturdy enough that the hammocks can safely be suspended. The tree’s canopy must be dense enough for the Fohts to recline amid the leaves without being easily seen.

They have since slept in trees on the campus of the University of Virginia in Charlottesville (“We thought Jefferson would approve,” said Cory, referring to Thomas Jefferson, the founder of the school), and near Arlington National Cemetery. In Richmond, where they spent about a week’s worth of nights in two different trees, their favorite perch was a towering oak next to a church parking lot, until one Sunday morning when they awoke to find a police officer guarding cars parked by worshipers. (They stayed in their hammocks until the congregation had dispersed.)

While in trees, the brothers said, they sometimes catch glimpses of people who do not know they are being observed, or overhear snippets of conversation from those who imagine that they are alone. They have experienced a few close encounters with birds, they said, but have been lucky to avoid raccoons. The soft sway of the branches usually lulls them to sleep, though one recent night in Central Park, Dana had a disturbing dream in which a cord used to secure one end of his hammock came loose, leaving him to swing among the leaves like a pendulum.

The brothers, who graduated from Florida Gulf Coast University in 2007 and want to make documentaries, said that they were editing footage to create a 10-minute film about life in the beech, which they plan to post on YouTube. The two came to New York in September to participate in a rally for the preservation of community gardens, then decided to stay. They have spent some rainy nights in friends’ apartments, and occasionally hang their hammocks in the back room of a bicycle-repair workshop in Brooklyn where they volunteer as mechanics.