Fergusson Island lies off the south-eastern end of New Guinea and is the largest landmass in the D'Entrecasteaux and Trobriand Island Endemic Bird Area (EBA). We conducted audiovisual and camera-trap surveys of eastern Fergusson during September 2022 and recorded 97 bird species, documenting breeding and vocalisations for several of the EBA's endemic taxa. Notably, we provide the first confirmed documentation of the ‘lost’ insularis subspecies of Pheasant Pigeon Otidiphaps nobilis (often recognised as a species, Black-naped Pheasant-Pigeon), in 126 years, observations of six bird species not previously recorded on Fergusson, and nesting data for two regional endemics, Goldie’s Bird of Paradise Paradisea decora and Oya Tabu White-eye Zosterops crookshanki. Our new distributional records mostly involved either migratory or open-country species, highlighting the value of surveying across seasons and habitats.

The name Catharus fumosus Ridgway, 1888 has traditionally been placed among the synonyms of Black-headed Nightingale-Thrush C. mexicanus (Bonaparte, 1856) and applied at subspecies rank to the population ranging from Nicaragua to Panama (C. m. fumosus). Recent data support species rank for C. fumosus, but the availability of the name is contested. Allan Phillips claimed that the C. fumosus holotype (USNM 101765) was a hybrid with ‘C. fuscater’ (= C. [f.] hellmayri von Berlepsch, 1902, recently elevated to species), then re-described the Central American taxon under the name C. m. carrikeri A. R. Phillips, 1991. World checklists are now in conflict. Here, I review the relevant history and compare USNM 101765 to a geographically widespread sample of study skins of the putative parental forms, yielding little support for the hybrid hypothesis. This is the fourth in a series of papers concerning historical aspects of Catharus taxonomy and nomenclature.

Banda Myzomela Myzomela boiei (S. Müller 1843) is a small honeyeater distributed in two subspecies across three island groups in Maluku Province, Indonesia: M. b. boiei on the Banda Islands, and c.350 km to the south, M. b. annabellae on the Tanimbar Islands and Babar. We compare data from 28 museum specimens and 21 sound recordings, and report the results of 152 playback experiments, to investigate the taxonomy of these three populations. Compared to M. b. annabellae, M. b. boiei has a c.10% longer wing, bill and tarsus, more extensive black breast-band, duskier posterior underparts, and a highly divergent song; in playback experiments, M. b. boiei proved unresponsive to recordings of M. b. annabellae. However, the songs of M. b. annabellae on the Tanimbars and Babar are also highly divergent, with populations on both islands unresponsive to the song of the other. Birds on Babar are also slightly larger than annabellae on the Tanimbars (with a c.10% longer tail) and may have more scarlet on the back. We consider the vocal differences between the three populations to be highly indicative of reproductive isolation and recommend they be treated as three independent species under a modern interpretation of the Biological Species Concept. Because no nomen is available for the Babar population, we name it as a new species.

Six subspecies of Common Chiffchaff Phylloscopus collybita are usually recognised, of which three are known to occur in north-west Europe: P. c. collybita, P. c. abietinus and P. c. tristis. Based on a newly developed mitochondrial DNA sequencing protocol, P. c. brevirostris and P. c. caucasicus were recorded in northwestern Europe for the first time. Both taxa occur at the south-eastern edges of the species' breeding range, in the Middle East and the Caucasus, respectively. A single P. c. brevirostris was recorded in Germany in spring (May 2022), whereas the five P. c. caucasicus were all recorded during late autumn and early winter (between the third week of November and mid-December) in the Netherlands and Germany. The contact calls of three of the P. c. caucasicus as well as the single P. c. brevirostris supported the genetic data. We postulate that P. c. caucasicus might be overlooked in Western Europe, rather than an exceptional vagrant. Movements by both taxa outside the breeding season are largely undescribed.

Why do the Cyclops Mts., reputedly the fourth highest of New Guinea's ten outlying mountain ranges, support the second-lowest number of upland species? We surveyed Cyclops birds up to the summit. Despite observing most previously recorded upland species, we added only four to the prior list. Still unrecorded from the Cyclops are 22 upland species known from all or almost all other outliers. Most of those missing species are so common and/or conspicuous elsewhere that their apparent absence from the Cyclops is probably real. We compared upland species presence/absence in the Cyclops to elevational floors of upland species in the higher and much more species-rich Foja Mts. Unsurprisingly, Foja upland species with low Foja floors are better represented in the Cyclops than are species with Foja floors near or above the elevation of the Cyclops summit. But, surprisingly, the Cyclops are impoverished at low as well as at high elevations. The Cyclops summit avifauna consists of just eight species, most of them small forest understorey passerines endemic to New Guinea and absent from offshore islands, but abundant on the Cyclops summit. Only six subspecies are currently recognised as endemic to the Cyclops, none of them very distinctive—suggesting paradoxically that the Cyclops have not been difficult for upland species to reach, despite lacking so many apparently appropriate species. For most Cyclops upland species, three means of dispersal to the Cyclops readily suggest themselves: flying directly from other mountains, dispersal through the lowlands, or colonisation during Pleistocene cool phases with lowered climate zones. But those three mechanisms may not apply to 12 high-elevation Cyclops upland species endemic to New Guinea: we speculate about how they nevertheless arrived. We identify two factors contributing to Cyclops poverty in upland species: modest elevation (the summit is actually 250 m lower than the widely accepted value); and small area, hence frequent population extinctions resulting in low species number because of the species/area relationship.

The reproductive systems and nesting biology of the four species of the Madagascar-endemic Philepittidae are poorly known. Some are described as polygynous, with males forming leks, but without supporting evidence. Our photographs show bi-parental nest-building by two pairs of Schlegel's Asity Philepitta schlegeli, suggestive of social monogamy. We review and briefly assess reports on the reproductive strategy and nesting biology of all four species of Philepittidae.