IBISī’ bĭs (יַנְשֽׁוּף, Lev 11:17; ibis RSV; great owl KJV, ASV). This is another instance of RSV tr. being taken from some of the early VSS (LXX and Vulg.) but in two other passages it is tr. great owl (Deut 14:16) and owl (Isa 34:11). The root can mean either one that comes out at dusk or one that hisses. Neither would fit the ibis, nor the fact that the setting of Isaiah 34:11 is a desolate place. The tr. “owl” is much more likely. The “Sacred” ibis would have been known to the Israelites while in Egypt, where it was a deity, but it did not carry over to Pal. Another species, the glossy ibis, is an uncommon passage migrant.
International Standard Bible Encyclopedia (1915)
i’-bis. In Isa 34:11, yanshoph, which is rendered "owl," apparently indicates the sacred ibis (Ibis religiosa). The Septuagint gives eibis and Vulgate (Jerome’s Latin Bible, 390-405 A.D.) ibis; the Revised Version, margin "bittern."