More on “rainbow birds”

I recently wrote about “rainbow parrots”, species in which the colours of the rainbow appear on the bird’s plumage in the same order as in the visible spectrum: red, orange, yellow, green, blue, indigo, violet.

Here is another parrot (Eunymphicus cornutus, the horned parakeet) which shows the apparent effect:

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And the Nyasa lovebird (Agapornis lilianae) from Africa:

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Although I have focussed on parrots, there are some unrelated birds which also show a similar pattern including a number of birds in the tanager family (Thraupidae) or finch family (Fringillidae).

The bay-headed tanager, Tangara gyrola:

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The rufous-winged tanager, Tangara lavinia:

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The green-headed tanager, Tangara seledon:

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The blue-naped chlorophonia, Chlorophonia cyanea:

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The chestnut-breasted chlorophonia, Chlorophonia pyrrhophrys:

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And, maybe, the multicolored tanager (Chlorochrysa nitidissima):

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And from the Capitonidae (barbets), the male red-headed barbet (Eubucco bourcierii) has some rainbow effects (in the order of the spectrum):

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A particularly good example of a bird that is not in the parrot order but shows “rainbow” effects in its plumage is the orange-breasted bunting: Passerina leclancherii:

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The occurrence of this rainbow effect in birds other than parrots raises the question of whether it is simply a random effect in the colouration of some species, or whether there is some adaptive or developmental reason for their having plumage colours in the order seen in a natural rainbow.

Here are three more birds which show some juxtaposition of colours on their bodies that are also adjacent in the rainbow:

The golden-throated barbet (Megalaima franklinii):

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The pin-tailed parrotfinch (Erythrura prasina):

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The bar-bellied pitta (Hydrornis elliotii):

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Something is going on with some hummingbirds too. This species has the colours of the rainbow in order:

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From what I know of hummingbird plumage, I suspect this rainbow effect is due to structural effects in the feather pigments.

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6 responses to this post.

    • Posted by Julian O'Dea on November 26, 2014 at 6:03 am

      One possible explanation is that these patterns are simply cases where a lot of colours close on the spectrum are adjacent on the body, so as to provide a good test for species recognition and/or mate choice. Colours close on the spectrum would probably be harder to tell apart and therefore be a good test of perception.

      Reply

      • Posted by Julian O'Dea on November 26, 2014 at 9:26 am

        Green adjacent to blue and yellow adjacent to green are very common in the plumage of parrots. These are adjacent in the visual spectrum as well, of course.

  1. […] ADDENDUM: Some of these “rainbow parrots” are pictured at my earlier blog posts here and here. […]

    Reply

  2. Motmots are another possible group:

    Reply

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