Well, it seems that I must amend the title of this post. The latest taxonomy update (2019) changes two of my sighted Costa Rican species. These are: the Checker-throated Antwren, which now becomes the Checker-throated Stipplethroat (Epinechrophylla fulviventris), and the Steely-vented Hummingbird, now renamed Blue-vented Hummingbird (Amazilia hoffmanni); Amazilia rabiazul; Stahlamazilie; Ariane de Hoffmann. The respective Spanish and German names that I give here are by no means sure!
Here’s a new record for the house and, I think, for the village of San Antonio. This week a Blue-vented Hummingbird (Amazilia saucerrottei) joined the Rufous-tailed Hummingbirds, the White-necked Jacobins and the Green-breasted Mango at my two feeders. I found this species to be more difficult to separate from Rufous-tails than from the glittering green, really tiny Garden Emerald or Canivet’s Emerald. But then again, I know I’m not likely to have either of the two Emeralds in my garden, even though neighbour Sue Magree did once have a Garden Emerald at her house in San Rafael just 2 km away. The Rufous-tailed Hummingbird (Amazilia tzacatl) is found country-wide close to human habitation.
Here are a Steely-vented and a Rufous-tailed side by side:
Our constant companion: Rufous-tailed Hummingbird in Santa Rosa de Turrialba; photo by John Beer 
Blue-vented Hummingbird in Santa Rosa National Park; photo by John Beer
From these photos distinguishing between these two looks like a cinch, right? I still insist, however, that you must get a clear look at the tail to be absolutely sure. The Rufous-tailed’s bill is also more curved but with these very small birds (4″) it’s really not always easy.
Here’s a male Garden Emerald (3″) for a further comparison. No need to worry about female Emeralds because they have a white line behind the eye and pale underparts. The tail is more strongly forked than on the Steely-vented:
Birds for Beer 