The ecolodge at Itororó has a number of hummingbird feeders, with about three species visiting regularly when we were there: the white-throated hummingbird, violet-capped woodnymph, and Brazilian ruby. We also got brief looks at the scale-throated hermit and the glittering-bellied emerald. All except the emerald are Atlantic Forest endemics, meaning that this is the only place in the world that they’re found.

The Brazilian ruby is one of a number of hummingbirds that can dazzle you with the way their throat—or gorget, as ornithologists call it—changes color. Take a look below at two images I took of a Brazilian ruby male just a few seconds apart, and you can see what I mean.

Just by moving his head ever so slightly in one direction or another, he can change the intensity of color on that patch of feathers—or make the color patch go away almost completely.

I also shot a quick (6-second) video of a male Brazilian ruby flashing his throat patch:

Most of what I’ve read seems to suggest that male hummingbirds do this trick in order to impress the female hummingbirds. (Only the males have this ability.) But from what we observed at Itororó, it also seemed like they were doing it as a form of aggression, to defend their turf by shooing other hummingbirds away.

How they do it is a whole other subject, and one that I don’t fully understand. It has something to do with the way the light catches, and is reflected by, their feathers at different angles. If you’re feeling nerdy, you can read about the science of it here.

Meanwhile, the female Brazilian ruby doesn’t have the throat trick—but she doesn’t need it. As you can see in the photo below, she has a beauty all her own.

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