Stripe-tailed Hummingbird can be hard to pin down

Stripe-tailed Hummingbird (Eupherusa eximia): Colibrí colirrayado; Colibri à épaulettes; Streifenschwanzkolibri

Costa Rica is home to a multitude of hummingbird species. Gradually, and over many years, I have been able to be sufficiently sure of my identification skills to identify with certainty almost half of them within a decent walk of my house in San Antonio. Several species that definitely are present here have so far eluded me. One of these is the Stripe-tailed Hummingbird, a medium-sized species which distinguished by its white-striped outer tail feathers, most conspicuous in flight. In Spanish and German, as in English, its name calls attention to that field mark, but if the bird is perched it is not always easy to see:

Male Stripe-tailed Hummingbird; photo by Guillermo Saborío

I find the French name more helpful because it pinpoints the rufous shoulder patch. This is particularly prominent on male Stripe-taileds, as can be seen above on this individual photographed by Guillermo at Providencia, not far from Los Quetzales National Park but more than an hour´s drive from my location.

Female Stripe-tailed Hummingbird at Aquiares; photo by Larry Waddell

The rufous shoulder patch is a very useful aid to identification that is found in only two other Costa Rican hummingbird species. On Larry´s bird, a female with typically whitish underparts, the epaulette is still the most obvious field mark as long as the bird is perched. Happily, the Stripe-tailed Hummingbird has now appeared with some frequency just a short drive downhill from my house (or alternatively a fairly long walk) at Aquiares, which has recently become a birding hotspot thanks mainly to John and Larry, who contribute extensively to this blog . The Stripe-tailed Hummingbird is a fairly common species at many middle elevation sites from southeastern Mexico to Panama.

A rather longer drive (too steep uphill for my old legs to make it all the way) brings you to the rural community of Bonilla Arriba. Here is where another hummer with a rufous shoulder patch can reliably be found: the Black-bellied Hummingbird (Eupherusa nigriventris), a species endemic to Costa Rica and western Panama. It has also been recorded at Guayabo National Monument, a mere 2 km direct flight from San Antonio. Identification of the male with its very dark head and belly is not really a problem. At 3 inches it’s much smaller than the Stripe-tailed (Eupherusa eximia), but note also in the first photograph below the completely white outer 3 tail feathers, which are much more striking:

Male Black-bellied Hummingbird preening at Bonilla Arriba on the Turrialba Volcano Slope; photo by John Beer

The female Black-bellied Hummingbird does NOT have the dark plumage of the male, and since its shoulder patch is less marked, it can be more difficult to identify especially if no males are nearby.

Female Black-bellied Hummingbird at Rio Roca; photo by John Beer

Confusion of these two Eupherusa species with the 3-inch female Coppery-headed Emerald (Elvira cupreiceps) does seem possible where ranges coincide and if no shoulder patch is seen. However, the bill of this emerald species is noticeably decurved, as noted in the field guides (see Garrigues & Dean, The Birds of Costa Rica). Unfortunately, I do not currently have access to a photograph of an Elvira cupreiceps female.

The only other Eupherusa species that you may come across in Costa Rica is the Blue-tailed Hummingbird (Amazilia cyanura). Although it too has a rufous wing patch, it shows no white in the tail and is a rare species of uncertain status in the country.

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