On February 28 2025, the International Ornithological Congress (IOC) released the latest version of its world bird list (v15.1). This was later than usual, as vX.1 versions of the bird list are normally released during January:

Gill F, D Donsker & P Rasmussen  (Eds). 2025. IOC World Bird List (v15.1). doi :  10.14344/IOC.ML.15.1.

The IOC bird list is hosted on a dedicated World Bird Names website, which provides access to the list in various different formats. The list is updated twice a year.

The details of the changes in the v15.1 release can be found by clicking on the Updates tab on the IOC website. Here is a summary of the major amendments:

New to science

None

Splits

Eudyptes Penguins  +1 species

Butorides Herons  +1

Myzomela Myzomelas  +1

Zoothera Thrushes  +1

Stiphrornis Robins  +2

Aethopyga Sunbirds  +1

Arremon Sparrows  +1

Stilpnia Tanagers  +1

Lumps

There was an unusually high number of deleted species: 36. This may be due to progress having been made towards the harmonisation of the IOC bird list with other global taxonomies. In 2018, the Working Group on Avian Checklists (WGAC) was formed to record and later reconcile the differences between the major taxonomies, with the intention of creating a single worldwide list. Work began on compiling the new list in February 2021 and is now in the process of being concluded.

Xenoperdix Partidges  -1  [Rubeho Forest Partridge]

Arborophila Partidges  -1  [Siamese Partridge]

Phalacrocorax Cormorants  -1  [White-breasted Cormorant]

Leucocarbo Shags  -1  [Foveaux Shag]

Aerospiza Goshawks  -1  [Red-chested Goshawk]

Upupa Hoopoes  -1  [African Hoopoe]

Phoeniculus Wood Hoopoes  -1  [Grant’s Wood Hoopoe]

Nystalus Puffbirds  -1  [Chaco Puffbird]

Pteroglossus Aracaris  -1  [Brown-mandibled Aracari]

Melanerpes Woodpeckers  -1  [Velasquez’s Woodpecker]

Psittacara Parakeets  -1  [Red-throated Parakeet]

Melanopareia Crescentchests  -1  [Double-collared Crescentchest]

Nesotriccus Tyrannulets  -1  [Northern Mouse-colored Tyrannulet]

Philemon Friarbirds  -2  [New Guinea Friarbird, Hornbill Friarbird]

Sericornis Scrubwrens  -1  [Perplexing Scrubwren]

Psophodes Whipbirds  -1  [White-bellied Whipbird]

Batis Batises  -1  [Reichenow’s Batis]

Vireo Vireos  -1  [Providencia Vireo]

Terpsiphone Paradise Flycatchers  -1  [Annobon Paradise Flycatcher]

Melaniparus Tits  -1  [Cinnamon-breasted Tit]

Alaudala Larks  -1  [Athi Short-toed Lark]

Phyllastrephus Greenbuls  -1  [Placid Greenbul]

Pycnonotus Bulbuls  -3  [Dodson’s, Somali, Dark-capped]

Aegithalos Bushtits  -1  [Burmese Bushtit]

Prinia Prinias  -1  [Black-faced Prinia]

Scepomycter Cisticolidae Warblers  -1  [Rubeho Warbler]

Gracula Hill Mynas  -1  [Enggano Hill Myna]

Lamprotornis Starlings  -1  [Miombo Blue-eared Starling]

Saxicola Stonechats  -1  [Madagascar Stonechat]

Thamnolaea Cliff Chats  -1  [White-crowned Cliff Chat]

Dicaeum Flowerpeckers  -1  [Striped Flowerpecker]

Cinnyris Sunbirds  -1  [Hofmann’s Sunbird]

Rhodopechys Finches  -1  [African Crimson-winged Finch]

Revision and resequencing of families

Family: Tityridae – Tityras, Becards, Sharpbill has been split into three families:

Family: Tityridae – Tityras, Becards & Allies  37 species
Family: Oxyruncidae – Sharpbill  1 species
Family: Onychorhynchidae – Royal Flycatchers & Allies  7 species

The following families have been fully or partially resequenced:

Family: Rallidae – Rails, Crakes & Coots

Family: Accipitridae – Kites, Hawks, Eagles

Family: Ramphastidae – Toucans

Family: Falconidae – Caracaras, Falcons

Family: Campephagidae – Cuckooshrikes

In the IOC bird list there are now 11086 extant species (net -27) ascribed to 255 families.

This is the first time the number of extant species in the IOC Bird List has fallen since at least v6.4 in 2017, when the total stood at 10660 species ascribed to 237 families.

All the v15.1 changes will be reflected in the 2026 editions of ATWB Companion Guides. These editions will be released commencing August 2025, after publication of the next version (v15.2) of the IOC bird list.

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Some details …

Each of the ATWB 2025 Companion Guides has a number of important features, including:

– A complete taxonomic listing of bird species

– An indication of where each bird family and species can be found in its native state

– Spotlighted species that have a restricted regional or worldwide range

However, perhaps the key feature of all eBooks in the Companion Guide series is the way you can quickly and simply access relevant, up to date online information about every featured bird species. If your reading device is connected to the internet, a single click will take you to a search results page for a species, from where you can continue to search for additional information to whatever level of detail you desire.

The ‘All the World’s Birds’ series of Companion Guides derives its taxonomy, English names and scientific names from The IOC World Bird List, an open access resource maintained by the International Ornithological Congress (IOC). The IOC bird list is hosted on a dedicated World Bird Names website, which provides access to the list in various different formats.

The version of the IOC bird list used in the ‘All the World’s Birds 2025’ series of Companion Guides is Version 14.2, published August 21 2024.

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