The natural question is how much booze can a bat consume before drunkenness affects it's behaviour. Luckily, a recent paper in PLoS ONE has done the homework, as Ars Technica reports:
To test the fruit bat's alcohol tolerance, researchers from Canada gave two groups of bats, from a variety of different species, a sugar water drink. One of the group's drinks was spiked with 1.5 percent alcohol, and both groups were made to drink the same amount per gram of body weight. After waiting a short time, the bats were then released, whereupon they flew through an obstacle course. The researchers measured the time it took to get through the course and how often the bats collided with obstacles. In addition, the echolocation calls were recorded to see if those varied.According to the research, a large portion had blood alcohol concentrations of 110mg per 100mL or greater, yet still maneuvered the course quickly, and without obstacle collision.
No word on how their performance was affected in other areas.