Well, that's one of the rubs for sure. It doesn't help the (in this case) Christians' cause when you have fundamentalists trying to read the Bible (and mainly the book of Genesis) as a sort of scientific primer when, in fact, it was never intended to be read as such. Yeah, it's telling to read some of the absurdities in the Bible (for instance, in Leviticus 11:13-19 God himself says that a bat is a type of bird). Passages like this can be used to demonstrate that either (a) the God of the Bible was a moron (and therefore not truly "God" as many pseudo-philosophical Christians would describe him), or (b) the people who claimed God told them this were lying.
Here is the section of text from which you are speaking.
13"And these you shall detest among the birds; they shall not be eaten; they are detestable: the eagle, the bearded vulture, the black vulture, 14 the kite, the falcon of any kind, 15 every raven of any kind, 16 the ostrich, the nighthawk, the sea gull, the hawk of any kind, 17 the little owl, the cormorant, the short-eared owl, 18 the barn owl, the tawny owl, the carrion vulture, 19 the stork, the heron of any kind, the hoopoe, and the bat.
20"All winged insects that go on all fours are detestable to you. 21 Yet among the winged insects that go on all fours you may eat those that have jointed legs above their feet, with which to hop on the ground. 22 Of them you may eat: the locust of any kind, the bald locust of any kind, the cricket of any kind, and the grasshopper of any kind. 23 But all other winged insects that have four feet are detestable to you.
If you took the time to study the text, you would see that the word translated as birds in Leviticus 11:13 is also translated insects in Leviticus 11:20-21,23. The Hebrew word is transliterated "oph ". The word means fowl or winged creatures. The context of these verses is what may be eaten and that which may not be eaten.