Fig. 4 in A taxonomic and conservation re-appraisal of all the birds on the island of Nias

Fig. 4. Sonograms of typical male calls of members of the Brown Wood Owl complex. a, Strix indranee maingayi from Fraser's Hill, Pahang, Malaysia ("hu-huhu-hu"; Xeno-Canto accession: XC142617; recordist: Marc Anderson); b, Strix [leptogrammica] niasensis from Bawolato ("hu, huuuu"; Xeno-Canto accession: XC482240; recordist: Frank E. Rheindt); c, Strix leptogrammica vaga from Lower Kinabatangan River, Sabah, Borneo ("huuuu"; Xeno-Canto accession: XC360090; recordist: Peter Boesman).