Saturday, January 22, 2011

The undescribed song of the Green-breasted Mountain-gem

Immature male Green-breasted Mountain-gem, 18 January 2011, Honduras
The Green-breasted Mountain-gem, a little known hummingbird from central Honduras and northwestern Nicaragua, sings a soft, scratchy rapid warble from inside dense vegetation. The song is audible only at close range (<7 m) and so far has not been formally described to science. Last month I recorded some songs of this type in Reserva Biol├│gica Monte Uyuca, Honduras, and wrote about that in this blog. Back then, I also recorded another song that I erroneously thought was this species but turned out to be Green Violetear.

Last week, Roselvy, Vicky and I went back there for the January bird banding pulse. Hummingbirds are so abundant in Uyuca that in the breeding season - which for them is now - they can be heard more or less constantly, often more than one species at a time. In the majority of the recordings I made this week, I have Green Violetear, a tireless singer, in the background. But let's start with a recording that has only the Green-breasted Mountain-gem:

This individual is singing a couple of shorter songs.

At times, the song is augmented with a trill at the end that sounds a bit like an old telephone ringing long distance (but higher). Listen for example to this individual, who first sings a few shorter songs, and finally a longer song with that trill (and ignore the staccato chip song in the background - that's the Green Violetear):

Here's another example. First a short song, then a longer song with that trill:

I recorded these songs during net runs, and didn't have opportunity for more extensive observations. Many Green-breasted Mountain-gems have already bred, evidenced by the proportion of immatures we caught. It seemed to me there was more singing going on now than a month ago; perhaps these are males teaching their sons how to sing. (I recorded a very odd, unstable Green Violetear song that I assume was a young bird practicing.)

Here's a recording of a young male calling. The bird was perched and looked around nervously while calling; once it spread its tail. These calls are unlike the contact and feeding calls uttered by the adults:

Here's a call uttered by an adult male while perched in a small tree at a height of 2 m. These are typical calls of this species, also heard when feeding:

Compare the song of the Green-breasted Mountain-gem with that of its sister species, the Green-throated Mountain-gem. First a Green-breasted:

And now a Green-throated, recorded by Nathan Pieplow in Chiapas, Mexico:

Note how similar those songs are!

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