http://www.google.com/search?q=califmed00148-0044.pdf

"Observations by Bunkerah on its use in New Caledonia revealed that natives could knock down three out of five fruit bats at 60 yards, using a river-bed stone with a sling. The Hawaiian slingstone was biconical, was 2.65 inches long and weighed 4.73 ounces, a little less than abaseball. The natives shaped it by rolling it between flat stones with motion to right and left as well as back and forth. Using a sling made from pandanus leaf, a skillful warrior hurled a stone so that it revolved on its axis like a rifle bullet."

Agreed, that is some amazing accuracy. If I could do that at 20 yards I would be extremely impressed with myself.  I'm amazed that they can achieve that kind of accuracy so far away. Stones really tend to drop fast that far out...accounting for that would be difficult.  I wonder if the bats were moving or stationary...it does say that they were knocked down...I would assume they were moving.

Ah, yes, I suppose you would be correct Aussie. I forgot about the noctural-ness of bats, they would most likely just be hanging.  I'm still very envious of their skill.