Why the bible says that bats are birds?

Leviticus 11:13 And these are they which ye shall have in abomination among the fowls

11:19 And the stork, the heron after her kind, and the lapwing, and the BAT.
Update: ask: wasnt the bible the so called "word of God" didnt he know that bats are different from birds when he created them?
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