Violet-headed Hummingbird (Klais guimeti); Colibrí cabeciazul; Violettkopfkolibri; Colibri à tête violette
Here’s a little hummer that can cause confusion, the Violet-headed Hummingbird. It is more common on the Caribbean side of the country and I’ve been able to observe it locally on quite a few occasions, most recently down at Chalo Porras’s property (1000 m elevation) in nearby San Diego this week.
Unfortunately for most of us, in the field it’s not easy to determine the colour of this tiny bird’s head. As with most hummers, the iridescence of head and gorget feathers appears only when viewed from certain angles.
When the Violet-headed Hummingbird pops into view, the first impression tends to be of a small hummer with a white post-ocular spot. This immediately excludes species without the white spot. Several of the remaining suspects are either much too big or are highland species, e.g. Fiery-throated Hummingbird (Panterpe insignis). The ‘fiery’ throat is often not visible, as in John’s photos below. This species does descend to lower elevations but note the not very obvious postocular spot and the lack of blue on the throat.
Fiery-throated Hummingbird at Paraiso Quetzal; photo by John Beer 
Fiery-throated Hummingbird at El Tapojo, Turrialba Volcano; photo by John Beer
Both of John’s shots above were taken at high elevations but the Violet-headed is rarely found above 1200 m. When I did finally encounter it several times here in San Antonio, at almost 1300 m, all those sightings were in the same year, between late August and early October 2014. Perhaps it was the same individual each time. Note the post-ocular spot on the bird below:
What species remain for comparison? I think only three, but the first two, the Magenta-throated Woodstar and the Scintillant Hummingbird, show considerable rufous on either underparts or tail and probably would not be considered. The last real possibility would be the migrant Ruby-throated Hummingbird, a bird that is our only truly migratory hummingbird, which is only present in Costa Rica for part of the year. It is very familiar to North American birders. On females and immatures the white throat and relatively longer bill should help to distinguish. Compare the following photo while remembering that both species are similar in size at 3 inches:
The morning excursion to San Diego was notable for several other interesting sightings, including two species that I have not seen there before. These are Pale-billed Woodpecker (Campephilus guatemalensis) and Crested Guan (Penelope purpurascens).
This means that I have now observed close to 170 different species at San Diego despite only sporadic visits. Actually, both species were to be expected there since they are both present at nearby Espino Blanco Reserve, yet this was only my second sighting ever close to home of this large and beautiful woodpecker species.
For the full list of the day’s sightings, see my checklist at:
Birds for Beer 