It’s that time of year again! Actually, it isn’t yet. eBird’s annual taxonomic updates are scheduled to go live in October 2024. However, given the complexities of the changes the plans are already well underway and the draft of this year’s changes is now available. Most of the significant changes seem to affect Old World (Eurasian and African) species this year but there are a few implications for Costa Rica, including its gaining two more species. Let’s see what changes we can expect to see in eBird in a few months.

First a quick shout-out to this year’s biggest change, the split of the Island Thrush of the Asian Pacific into 17 species! Closer to home, the House Wren is being split into 7. Both changes are primarily due to island populations tending to, through isolation, end up becoming endemic species.

English Common Name Changes Affecting Costa Rica

With the splits, many familiar birds will have some changes to their names.

  • Barn Owl will now be American Barn Owl in Costa Rica after being split into three species.
  • Herring Gull, a relatively infrequent visitor to Costa Rica, will now be American Herring Gull after being split into four species
  • House Wren will be Southern House Wren in Costa Rica and Northern House Wren in the United States after being split into seven species. The two continental species overlap in Mexico so there are no ID challenges in Costa Rica (and I get an extra species having seen it in the US!)
  • Rufous-naped Wren will be called Rufous-backed Wren in Costa Rica after two subspecies in Mexico have been elevated to species status.
  • Northern Mouse-colored Tyrannulet will now just be Mouse-colored Tyrannulet. This species was split into four some years ago, including separating the population of Cocos Island as one of Costa Rica’s country-level endemics. The Cocos Tyrannulet remains a species but the Northern and Southern species are being lumped back into one.

Scientific Name Changes Affecting Costa Rica

And for you bird nerds out there, other birds’ scientific names will be changing based on taxonomic changes. If you’re not into taxonomy, jump ahead to learn about the two species Costa Rica will gain in the next section.

  • The Mangrove Hummingbird will change from Amazilia boucardi to Chrysuronia boucardi, in the same genus as some Sapphire and Emerald hummingbirds.
  • The Yellow-breasted Crake found in humid wetlands like Caño Negro will change from Hapalocrex flaviventer to Laterallus flaviventer.
    • Small note on subespecie. The woodi subspecies is listed as being found in “NW Costa Rica” and the nominate flaviventer is listed as “Panama to Guianas…”There are many sightings in southwestern Costa Rica and it is unclear which subspecies they pertain to but I would assume they are flaviventer.
  • The Least Bittern will change from Ixobrychus exilis to Botaurus exilis.
  • The Western Cattle Egret will now have its English name hyphenated as Cattle-Egret as well as move from the Bubulcus genus to Ardea.
  • A few well-known raptors from the Accipiter genus are moving to a new genus Astur including the Bicolored Hawk, Cooper’s Hawk, and the Sharp-shinned Hawk.
  • The Sharpbill’s (Oxyruncus cristatus) name remains unchanged, but it will now be alone in the family Oxyruncidae. The other seven species of Flycatcher previously in the family will now be in the new family Onychorhynchidae. This new family will encompass the Tropical Royal Flycatcher, Ruddy-tailed Flycatcher, Sulphur-rumped Flycatcher, and Black-tailed Flycatcher in Costa Rica.
  • The White-fronted Tyrannulet, whose scientific name Phyllomias zeledoni pays homage to Costa Rica’s first ornithologist José Zeledón, will change genus to Acrochordopus together with the Rough-legged Tyrannulet of South America.
  • Two Jay genera are disappearing as the White-throated Magpie-Jay of the genus Calocitta and the Brown Jay of the genus Psilorhinus will be lumped into Cyanocorax with dozens of other Jay species.
  • Several Ant-Tanagers, including the endemic Black-cheeked Ant-Tanager, will be moving from genus Habia to a new genus Driophlox. Of the four species moving genera, two are found in Costa Rica with the Red-throated Ant-Tanager being the other to move to the new genus.

Two Extra Species

There are two more splits that will result in Costa Rica gaining more species to its list. First up is the Crested Bobwhite being split and the dividing line lies in Costa Rica. The populations of Guanacaste and the Central Valley will now be Spot-bellied Bobwhite. In the Southern Pacific, the Crested Bobwhite will still exist. Does it exist there is another question though. While it is listed in field guides, there are no sightings with documentation (photo or audio) of it in Costa Rica on eBird although there are a handful of reports by well-known, trustworthy birders from the area.

The final split involves the header image for this post. Brown Boobies are found across the world’s tropics. Those found in Costa Rica’s Pacific Ocean will now be known as the Cocos Booby while the Caribbean population, for now, will continue to be the Brown Booby. Although further splits in this species are possible in the future.

The name Cocos Booby is interesting. Had this split happened a few years ago it would be called Brewster’s Booby, in line with its new scientific name Sula brewsteri. However, due to the AOS decision to no longer use eponyms for bird names that was not an option. The South American Checklist Committee, which has split from the AOS over this topic, also approved Cocos Booby although with several dissents on the name.

The reasoning on the name was best summarized by the opinion of Don Roberson:

Now, we have an opportunity to give S. brewsteri another excellent English name: Cocos Booby. It parallels the name Nazca Booby nicely. Neither name includes all the breeding range of the Sula involved, let alone its at-sea distribution, but Cocos is a core breeding location, well represents core at-sea range, and does so better than the Nazca Plate did for Nazca Booby. It is really a fine choice: short, very memorable, reasonable accurate, and innovative in parallel with Nazca. While it is useful to name local resident landbird endemics for the island on which they occur (e.g., Cocos Finch), it is also appropriate to name a seabird after the tectonic plate which covers a good portion of both its breeding and its pelagic range, postulating, as did Pitman & Jehl, that it is likely that the “evolutionary history of this species is closely associated with the Cocos Crustal Plate.

Don Roberson via SACC Proposal 995

One of the reasons for dissent is based on the potential confusion, which was my first reaction on reading the name, with Cocos being the prefix for three endemic species to Costa Rica: the aforementioned Cocos Tyrannulet, Cocos Finch, and Cocos Cuckoo. Now there will be four Cocos species, just with one not being endemic to the island. Now we wait until October to see the changes reflected in our life lists.