I actually have some concept designs for a bat capturing arrow. Basically a whistling point with a trailing net held open with centrifugal weights. I need to build that one up one of these days.
Do you intend to catch the bat or let the bat catch the net/arrow.
Good question! I just noticed that if I shot an arrow at a bat, it would break course and swoop past the arrow in flight, I am guessing out of curiosity, being drawn to the sound. I thought if I had a whistling tip, the curiosity factor would be increased, and when a bat swoops past the arrow, the small parachute like net, trailing just several feet behind the arrow, would nab him. This would be for catching those high-flying open space bats, such as the Molossids, which can be difficult to get in a mist net set at ground level or in the canopy.
Sorry for the hi-jack.