Probably the most definitive work on the animals of the Torah is the one by
a famous Israeli naturalist Dr. Yehuda Feliks: "Hachay Vehatzomeach B'Mikrah
- (Creatures and plants in Tanach). I don't know if it's available in
English. Dr. Feliks has done a lot of original research and I've seen his
works quoted in halchic sources. He has corrected many mistakes in modern
Hebrew. Among some of his surprises is the identification of the Nesher as
the Griffin Vulture rather than the eagle and the chulda as the rat rather
than the weasel. Dr. Feliks also has written a sefer called: "Hachay
Vehatzomeach B'Talmud - the creatures and plants in the Talmud.
Samuel A. Kosofsky