Formally the word overlaps with both ostoir (‘soldier’) and oster2 (‘inn-keeper’) – two rare and problematic words with entirely different etymologies. The glosses in TLL ii 68.65, which include the surprising deviant form hostilur (more likely, it appears, to be a form of osteler1, i.e. ‘inn-keeper’) may indicate a certain level of confusion of the terms. There also seems to be some possible confusion between this word and ostriz1 (see commentary). On the difficulties of the taxonomy of medieval bird-names, see David Trotter, ‘Tote manere d’oiseaus: Les noms d’oiseaux en Anglo-Normand’, Cahiers de Lexicologie 103 (2013), 125-43.