The Cyclosa mulmeinensis
spider of Taiwan creates life sized decoys of itself to confuse predators and escape from being attacked. The clones were made out of leftover meals and egg sacs and were similar in size and color to the original spider. Scientists theorized that the benefit of becoming camouflaged in a crowd of peers outweighs the risks of being more conspicuous to attackers. It worked. Though enemy traffick increased, many of the wasps that prey on these spiders were fooled into attacking the decoys, leaving the spiders unharmed. While many homo sapiens still play the lottery, the Cyclosa mulmeinensis
have fully mastered the science of probability.
I don't know of any animal that actively builds a decoy of itself. Our study seems to be the first to empirically demonstrate the function of animal-made decoys
From the Upcoming ueue, submitted by coconutnut.