"Each spring, songbirds migrate thousands of miles to breed in Oregon's Cascade Mountains. Deep in a forest, Oregon State University researcher Hankyu Kim feels he has gotten inside the head of one species, the hermit warbler.
"These birds are territorial in the breeding ground, they set up their territories, and they fight with each other to defend it," he says.
Armed with this knowledge, a nearly invisible net strung between two repurposed fishing poles, a lifelike plastic warbler decoy and a looped recording of birdcalls, Kim's trap is set."
Source: NPR, 10/15/2018