One recent Saturday night, a group of strangers stood huddled together on the south side of Prospect Park Lake, whispering to each other and peering through overhanging tree limbs into the sky. It was not long after sundown—dark apart from the light of the moon and quiet except for some parkgoers grilling several bays east—when suddenly, a woman in a green beanie broke rank, stabbed her finger toward the stars, and yelled: "Right there!"
Above, a tiny figure danced against the night sky for about 30 seconds, striking a staccato rhythm that appeared both erratic and elegant. "YES! The bats are out! Sick!" exclaimed Roxanne Quilty, a co-founder of the four-year-old nonprofit Gotham Bat Conservancy, which promotes bat conservation in New York City. Nearby, two chattering tablets listened to the bat signals above through powerful microphones; they pitched down the soundwaves to a level audible to humans and, simultaneously, identified its species, which Quilty told the group was a big brown bat. Below, the two dozen participants of the conservancy's first "bat walk" of the year stood enthralled, before the skyward entity disappeared back into the darkness.