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| Cheerful Fantail Rhipidura laguceria Eaton & Berryman, 2026 from Babar (left) and Cinnamon-tailed Fantail R. fuscorufa P. L. Sclater, 1883 from the Tanimbars (right), Photographs: James A. Eaton (both taken in November 2022) |
Abstract
The Babar Islands, in the Banda Sea, Indonesia, have long been known to host several endemic avian taxa, but only recently have some of these been elevated to species rank. Here we investigate the internal taxonomy of Cinnamon-tailed Fantail Rhipidura fuscorufa P. L. Sclater, 1883, a monotypic passerine found on the Tanimbar Islands (from which it was described) and, 135 km to the west, on the Babar Islands. We compare differences between these populations using 19 specimens and 18 sound recordings, finding that while morphologically they differ subtly (Babar birds are slightly darker above, less extensively cinnamon below), the two have consistently different songs. Moreover, across 132 playback experiments, we find that both populations always ignore allopatric song but typically respond to sympatric song. On the basis that these lines of evidence likely represent barriers to reproduction, we consider the population on the Babar Islands to be taxonomically distinct from that on the Tanimbar Islands. In the absence of an available name, we describe it as a new species.
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| Photographs of Cinnamon-tailed Fantail Rhipidura fuscorufa from Babar (left) and the Tanimbars (right), both taken in November 2022 (James A. Eaton) |
Rhipidura laguceria sp. nov.
Diagnosis.—Differs from Tanimbar R. fuscorufa in its consistently darker forehead, crown, nape, mantle and back that are often discernible in the field (pers. obs.); it also has, on average, less extensive buffish on the underparts, being largely confined to the belly (not extending to the lower breast). The most pronounced difference, however, is in the two species' song: R. fuscorufa delivers strophes of 8–18 staccato whistles which randomly change in pitch, while R. laguceria emits a series of 6–8 notes that steadily ascend in pitch (Fig. 4). Birds on each island are unresponsive to allopatric song.
Northern Fantail Rhipidura [rufiventris] hoedti (of Romang, Damar, Leti, Moa and Sermata) and R. [r.] assimilis (Kai Islands)—sometimes recognised specifically as Banda Sea Fantail and Kai Fantail respectively (Eaton et al. 2016, 2021, del Hoyo & Collar 2016)—has an obvious white-streaked grey breast-band, greyer head and upperparts (with a much broader supercilium in assimilis), plain wings lacking extensive cinnamon, much less richly coloured belly (appearing almost whitish in hoedti and pale buff in assimilis) and white (not cinnamon) outertail feathers. They also have very different vocalisations (Eaton et al. 2021).
Etymology.—Because the pleasing song of this taxon is its most distinctive attribute, we name the species for its vocalisations (lagu ceria = Indonesian for ‘cheerful song’). We employ the name as a noun in apposition.
Vernacular names.—While the English names ‘Tanimbar Fantail’ and ‘Babar Fantail’ are ostensibly appropriate for R. fuscorufa s. s. and R. laguceria respectively, the Tanimbar islands host two other sympatric fantail species—Supertramp Fantail R. semicollaris and Long-tailed Fantail R. opistherythra—the second of which is also endemic to the islands. Accordingly, we prefer the English names ‘Trembling Fantail’ for R. fuscorufa and ‘Cheerful Fantail’ for R. laguceria, given that their distinctive vocalisations have led us to propose separating them taxonomically.
Geographic distribution.—Endemic to Babar, Indonesia, and perhaps occurs too on the island's five small satellites, although these have not been explored ornithologically.
James A. Eaton and Alex J. Berryman. 2026. A New and Cryptic Fantail Species from the Babar Islands, Maluku Province, Indonesia. Bulletin of the British Ornithologists’ Club. 146(2); 203-215. DOI: doi.org/10.25226/bboc.v146i2.2026.a6 (3 June 2026)
https://www.researchgate.net/profile/James-Eaton