It's been a while since my 5-week trip to Argentina and the Southern Oceans, however, between now and then a couple of birds have been through taxonomic splits. In 2018, the resident Chivi Vireo got split from the migratory Red-eyed Vireo; from this news I quickly remembered photographing a Red-eyed Vireo-type at Costenera Sur, where upon closer inspection, appears I had clearly photographed a Chivi!
Formally considered to be the same species as Red-eyed Vireo, genetic analysis reveals the Chivi Vireo is closely related to the Black-whiskered Vireo, despite near-identical in appearance to Red-eyed. The subtle differences from Red-eyed include the lack of a red eye(!), yellow under-tail coverts and a yellow wash to the neck sides.
This site in Buenos Aires is on the edge of the Chivi Vireo's distribution, where they comonly occur further North and West across much of South America.
|Chivi Viero at Costanera Sur, B.A.|