New Guinea and its satellite islands are justly renowned for their spectacular and highly diverse, endemic avifauna. The oceanic island of Biak and its satellites, in Teluk Cenderawasih (formerly Geelvink Bay), Papua province, Indonesia, has an avifauna of c.159 species including the largest number of endemics of any island in the New Guinea region: seven species are strictly endemic to Biak and another six are shared with other Teluk Cenderawasih islands but not Yapen. Despite Biak attaining an elevation of c.1,034 m there are no species whose range on Biak is known to be entirely montane. We provide a physical description of Biak and its twin Supiori, and discuss the biogeography and conservation of their birds. We present a detailed checklist of all species recorded to date. Since the publication in 1939 of Mayr & Meyer de Schauensee, 66 species have been added to the Biak list, of which Short-eared Owl Asio flammeus and Black-winged Stilt Himantopus himantopus are new for the entire Australo-Papuan region and Grey Heron Ardea cinerea only the second for the region and first for New Guinea; 47 of these additions are also first records for any island in Teluk Cenderawasih. An appendix summarises the distribution and status of birds in Teluk Cenderawasih (excluding mainland New Guinea species only on Yapen).

Mexican Woodnymph Thalurania ridgwayi was long included in the genus Thalurania. A previously published molecular phylogenetic study found that this species is in fact sister to the genus Eupherusa. We discuss whether ridgwayi is better lumped with Eupherusa or placed in a different genus, and consider that the latter arrangement best reflects the multiple morphological differences between ridgwayi and Eupherusa. Consequently, we describe a new genus for ridgwayi.

Rüppell's Parrot Poicephalus rueppellii was until recently considered to be a monotypic species. Birds from parts of north-western and west-central Angola, however, differ significantly in colour and size from the better-known populations across the rest of their range, which fact was overlooked until very recently. Because the name rueppellii was originally applied to the less-known Angolan population, it was the commoner southern population that lacked a taxonomic identity. The latter was described as Poicephalus rueppellii mariettae Hubers & Schnitker, 2022.

We review specimens and sight records of small black-and-white Puffinus shearwaters in Kenya and Tanzania. An early specimen of an Audubon's Shearwater P. lherminieri sensu lato found inland at Limuru, Kenya in October 1963, long held to represent taxon bailloni (now treated as Tropical Shearwater P. bailloni), is reassigned here to P. b. nicolae. We refer three other specimens and two well-documented sight records to Persian Shearwater P. persicus persicus and a third sight record in northern Tanzania to P. persicus. We suggest that nominate persicus is a regular visitor to the central Kenya coast in December–March, probably as far south as the Pangani region of north-east Tanzania at least, concurrent with a seasonal upwelling event on the Kenya Banks associated with the north-east monsoon. Tropical Shearwater, however, is no more than a rare visitor to East African shores based on current evidence. Our data clarify the status of these shearwaters in the region, provide additional biometric data to complement published sources, and extend the western Indian Ocean non-breeding range of the nominate subspecies of Persian Shearwater approximately 2,000 km south from northern Somalia.

Chestnut Owlet Glaucidium (capense) castaneum and Albertine Owlet G. (c.) albertinum are poorly known members of the African Barred Owlet Glaucidium capense complex, confined to the Albertine Rift of East Africa. Recent taxonomic treatments have seen them variously considered as subspecies of capense, as separate monotypic species or, in the case of castaneum, a polytypic species. A paucity of museum material and field knowledge of each, combined with oversight and misinterpretation of some primary literature, has contributed to this uncertainty. This study reassesses their status and corrects numerous errors, misunderstandings and contradictions concerning specimen material, distribution, morphology and voice. Only four specimens of castaneum are known, there are no documented observations of the bird in life and no acoustic recordings. There are seven specimens of albertinum in collections. No field sightings have ever been documented but several recordings attributed to albertinum exist. Despite its close similarity to the voice of capense, there is no published evidence that albertinum reacts to playback, unlike the remaining taxa of the complex. I conclude that castaneum is a modestly distinct subspecies of capense. In contrast, albertinum, which differs conspicuously from the others in the complex by its disproportionately short tail, and which may be parapatric with castaneum, merits treatment as a species.

In the 19th century the black-shouldered variety of Indian Peafowl Pavo cristatus was erroneously viewed by many as a separate species, named P. nigripennis. Others had doubts about its taxonomic status, but Darwin presented firm evidence for it being a variety under domestication, which treatment is now well established and accepted. It being a colour variation rather than a wild species was important for Darwin to prove, as otherwise it could undermine his theory of slow modification by natural selection in the wild.

Dulit Partridge Rhizothera dulitensis is an enigmatic galliform endemic to the Bornean highlands. Usually, the species is reported as having been collected at four localities (three in Sarawak, one in Sabah) and as recently as the 1930s. However, a review of the evidence (just eight known specimens) finds that it can be confirmed at only three sites, and the whereabouts of one of these has previously been misunderstood. Moreover, the specimens were procured over just eight years, between 1894 and 1902, with recent suggestions of the species' collection in the 1930s probably a misinterpretation of a single source. With more than 120 years since the last record, there is no information on its current population size and trend, such that R. dulitensis is probably best listed as Data Deficient on the IUCN Red List. Surveys of little-explored parts of its presumed range, especially those furthest from habitation, are urgently required.

We report five new records of Blue Petrel Halobaena caerulea in Uruguay; three individuals were found stranded on the coast in 2005, 2016 and 2018, and two were recorded at sea in the economic exclusive zone in 2021 and 2022. These few records suggest that the species' presence in Uruguayan waters is no more than occasional. However, its similarity to, and association with prions, together with the fact that this petrel does not usually approach fishing vessels, could mean that it is under-recorded.

From its description in 1863 until the 1920s, the authority for the name Spizaetus philippensis was almost universally agreed to be J. H. Gurney, but from the 1930s it has normally been ascribed to J. Gould. This paper demonstrates that this alteration of the authority was incorrect; it should be J. H. Gurney. The two syntypes of the taxon are currently held by the Natural History Museum at Tring.