Bioacoustics of Gerygone magnirostris

Taxonomy Although Salvadori (1878) could not attribute the two types in Leiden Museum to any species known to him, Mayr & Meyer de Schauensee (1939) emphatically listed hypoxantha as a subspecies of magnirostris based on Ripley’s two specimens . Mayr also described the immature, which is likely to be the source for the confusing reports of ‘another’ Gerygone on Biak (see Gibbs 1993 ). Treatment as a distinctive subspecies of G. magnirostris was subsequently followed by Rand & Gilliard (1967) and Beehler & Pratt (2016). The latter noted that SvB and KDB who are familiar with the species’ song had advocated treating hypoxantha subspecifically. Conversely del Hoyo & Collar (2016) and Gregory (2017 , 2020 ) treated this taxon as a full species but without a detailed assessment other than to note its taxonomy is unstable and that it has ‘clear yellow in plumage and is confined to a long-isolated island.’ Status Biak endemic subspecies. Infrequently encountered by collectors as evidenced by just four specimens : von Rosenberg ( Salvadori 1878 ) obtained the two syntypes and Ripley ( Mayr & Meyer de Schauensee 1939 ) collected two more, the only examples he encountered. Although infrequently observed by previous visitors, increasing familiarity with its vocalisations coupled with the possibility of it being an endemic species has resulted in numerous records since c .2006 between mid July and early November (eBird). Voice The song of Biak birds fits well with the general description of the species’ geographically variable song: ‘a lilting, repetitive, musical, typical gerygone-sequence’ ( Pratt & Beehler 2015 , Gregory 2017 ), resembling closely that of Australian G. m. cairnsensis (Beehler & Pratt 2016).