Taxonomic Changes to the AOU Checklist

Last week, the American Ornithologists' Union issued the 49th Supplement (pdf) to their Check-List of North American Birds. The AOU's checklist, unlike the ABA's, covers all of North America from the Arctic to the southern boundary of Panama, excluding Greenland but including Hawaii and islands in the Caribbean. After the current revision, it represents 2,048 species.

The biggest news is that the AOU reshuffled the subfamily Larinae, the gulls. Previously, most of the North American Larinae were assigned to the genus Larus with the exception of some small species such as kittiwakes (Rissa sp.) and Ivory Gull (Pagophila eburnea). The current supplement breaks Larus into four genera. White-headed gulls remain in the genus Larus. Hooded gulls are split into three new genera: Chroicocephalus, Hydrocoloeus, and Leucophaeus. There is also one new genus, Creagrus, based on recent sightings.

The gulls on the AOU list are now ordered as follows:

Creagrus furcatus Swallow-tailed Gull.

Rissa tridactyla Black-legged Kittiwake.
Rissa brevirostris Red-legged Kittiwake.

Pagophila eburnea Ivory Gull.

Xema sabini Sabine’s Gull.

Chroicocephalus philadelphia Bonaparte’s Gull.
Chroicocephalus cirrocephalus Gray-hooded Gull.
Chroicocephalus ridibundus Black-headed Gull.

Hydrocoloeus minutus Little Gull.

Rhodostethia rosea Ross’s Gull.

Leucophaeus modestus Gray Gull.
Leucophaeus atricilla Laughing Gull.
Leucophaeus pipixcan Franklin’s Gull.

Larus belcheri Belcher’s Gull.
Larus crassirostris Black-tailed Gull.
Larus heermanni Heermann’s Gull.
Larus canus Mew Gull.
Larus delawarensis Ring-billed Gull.
Larus occidentalis Western Gull.
Larus livens Yellow-footed Gull.
Larus californicus California Gull.
Larus argentatus Herring Gull.
Larus michahellis Yellow-legged Gull.
Larus thayeri Thayer’s Gull.
Larus glaucoides Iceland Gull.
Larus fuscus Lesser Black-backed Gull.
Larus schistisagus Slaty-backed Gull.
Larus glaucescens Glaucous-winged Gull.
Larus hyperboreus Glaucous Gull.
Larus marinus Great Black-backed Gull.
Larus dominicanus Kelp Gull.

The new result came as a result of mitochrondrial DNA studies. Those species remaining within the genus Larus seem likely to be reordered in a future supplement.

Other changes included:

• Merging Mangrove Black-Hawk (Buteogallus subtilis) with Common Black-Hawk (B. anthracinus) as a subspecies,
• Adding Pallas’s Leaf-Warbler (Phylloscopus proregulus) and Song Thrush (Turdus philomelos) based on recent sightings,
• Splitting Eastern Spot-billed Duck (Anas zonorhyncha) and Gray-cheeked Nunlet (Nonnula frontalis) from extralimital species,
• Changing the English name of Phoenicopterus ruber to American Flamingo as Greater Flamingo (Phoenicopterus roseus) was split into a new species,
• Placing flamingos (Phoenicopteridae) after grebes (Podicipedidae),
  
• Changing six English names within the genus Turdus from robin to thrush,* and
• Removing hyphens from violet-ears (now violetears).

Read the full supplement (pdf) for further changes and the reasoning behind them.

All of your field guides are now obsolete (if they weren't already).

* Turdus migratorius is still American Robin, for those who are wondering.