Are bats birds? Who would even ask such a question?
Skeptics. Here's why:
"These are the birds you are to detest and not eat because they are detestable: the eagle, the vulture, ... the hoopoe and the bat" (Lev 11:13, 19).
Are bats birds, or is this a scientific or factual error in the Bible?
Neither; it's actually a translation issue.
Our society categorizes animals based on all sorts of characteristics — physical, behavioral, internal, and external. We have people who are paid to sit around doing nothing but this; our system is going to be more complicated. Ancient Hebrews used a much simpler system, for example, things-that-swim, things-that-crawl, and things-with-wings. Their system wasn't wrong, just different.
But their system doesn't always translate smoothly into English. "Things-with-wings" translates fine as "bird" until you get to bats.
That's the case with many passages of the Bible, whether they appear to be "errors" or not. To properly understand the Bible, we have to strive to put ourselves in the heads of the authors and their audiences. When we read the scriptures as if they were written by and to twenty-first century Americans, we are bound to go astray.