As part of the experiments, most of them between 2009 and 2011, McGrann and his team hiked the rugged mountain trails, first listening, then recording. They dispatched more than 500 recorders programmed to turn on and off at specific times. Later, after retrieving the devices, they fed the data into a computer, which visualized the songs. McGrann listened — and watched. "With the software, I could see the songs of the birds as I was listening to the recordings," he explained.