Kitto's Popular Cyclopedia of Biblial Literature
Unclean Birds the species which the law forbade the Israelites to use for food (Leviticus 11 and Deuteronomy 14) include bats, because in the most ancient classifications of animals, all flying animals were considered to belong more to birds than quadrupeds; in other respects the list is confined nearly to the same genera and species as are at the present-day rejected in all Christian countries. There are only twenty named; but in the text the additional words 'of the like kind' clearly imply sometimes even more than genera, and the explanations of the law superadded by human authority indicate several which do not occur in either list. Every ornithologist who reviews this question with care will feel that, with certain exceptions, the proposed identifications cannot be regarded as claiming entire confidence.
Kitto, John, ed. Entry for 'Unclean Birds'. "Kitto's Popular Cyclopedia of Biblial Literature". https://www.studylight.org/encyclopedias/eng/kbe/u/unclean-birds.html.