Orange & white

Every now and then I’ve sneaked a little commentary on colour into my posts and it’s time for another one. This time it’s on the delightful orange with white trim pattern that seem to turn up on occasion. While there are plenty of orange-red animals out there (tigers, orangs, maned wolves, foxes, coati) and at least a few of them with white parts, the ones I’ve been thinking about are the red river hog, congo buffalo and bongo. All three are fairly large herbivores (OK the hog less so, but it’s not a small animal) and all live in fairly dense forested environments in the Congo area. All three are predominantly orange with white ear tips and white ‘trim’ (white stripes for the bongo and hog, white tails for the hog and buffalo) and for the record all three have rather dark lower legs.

Some colour combinations or patterns are pretty obvious and have a clear function. Dappled coats are common in forests where they match the light pattern through the leaves. Desert animals tend to be pale and sandy colours, those in grasses tend to have stripes and so on. What I find interesting here is that you do have a set of species with relatively similar habits living in a similar environment and they have all convergently struck on a very similar coat pattern.

White ear tassels and tails are often considered signalling structures which makes sense in a dark environment. But why orange and the dark legs? It seems too much of a coincidence (but of course still could be) that they all share this coat colour pattern given the shared behaviour and environment, but I can’t think what it might be. I’ve had a chat to a few colleagues and no one seems to have any concrete ideas but it’s something that’s been buzzing in my brain for a while and features several of my favourite animals, so it’s a good excuse to put these up and muse a little on colour patterns.

4 Responses to “Orange & white”

  1. 1 kattato Garu 02/05/2012 at 1:38 pm

    Interesting observation – who is this colour for? Most mammals (both herbivores and predators) don’t have colour vision so the way they look to us is not how they see each other. My guess is that orange is a pretty good camo colour in the gloom of the understorey (or in open grassland for that matter).

    • 2 David Hone 02/05/2012 at 2:13 pm

      Well mammals can see some colour, just not that much. I can’t see it being great in the understory as aniamls that really are well camoflaged don’t go for it (jaguars perhaps, but leopards are more yellow than orange, and things like genets and ocelots aren’t orange, and so are very few ‘classic’ prey species like monkeys and squirrels and rodents (though there are some). I can see it doing better in long grasses, but then things that do live in long grasses don’t tend to be orange (and certainly these three don’t).

  2. 3 Robert A. Sloan 03/05/2012 at 2:56 am

    I wondered about this coloration myself for years because of a completely different animal – Felis domesticus. Orange and white cats are very common. I can understand how the inverted triangle on a cat’s face helps break up recognition, it doesn’t look like a cat face if you see it in the shadows of foliage. Even if you see it as a cat face, it’s confusing and looks like the animal’s facing the other direction.

    But why the bright orange and white patterns in the first place? My first thought was “humans selected for that because they’re pretty,” and that orange and white cats don’t have as much advantage in camouflage. But their success as hunters doesn’t seem any less than gray tabbies.

    I can think of several things that might affect it.

    1) Red iron-rich soils. Many of the warm places I’ve lived have bright orange-red dirt. In those areas, an orange-red animal with white bits laying on the ground has an outline broken up by the white markings to look like separate objects and is the color of the background.

    2) There’s more orange in green foliage than you’d think. As an artist, I’ve been focusing on impressionism in the past few years starting with a great class on color in 2008.

    A verdant green forested place with a bright green undergrowth looks unreal if you just paint it in shades of green. Even if you pull all the greens from your pastel or crayon box, really reaching between the dull olives and bright yellow greens and blue greens that are almost turquoise, the effect is monochromatic.

    Some painters get so upset at this they literally won’t use green in painting forests or lawns. Green Avoidance is too much for me. I like the sense of an overwhelming cool green forest light. But the more I paint it, the more often I need to use orange and violet to make that green look true and real.

    I stared at clumps of foliage in the summer and noticed that when I’m using flashes of orange in sunlit areas, that’s why the orange strokes in green foliage in my painting read true. They’re there. Some of it is that a muted yellowish color will seem more reddish because of the afterimage from the green reddening it.

    Local color isn’t how color appears in nature.

    Sky light, not the direct beam of sunlight but reflected light from the dome of the sky, is blue light. The light from your window when the sun’s not directly pouring through it will be blue. Shine a blue light on an orange object and it’ll be cooled and muted. Reflected sky light shows up in the cast shadows of objects and in the modeling shadows on them – the place where the shadow of an ear covers a patch of orange hide will be gray. Reflected green from surrounding vegetation will also mute reddish areas.

    The green leaves themselves have patches of orange where reflected light from reddish bark strikes a highlight – and the highlight is yellowish direct sun.

    I wind up using the orange more than I ever expected to in landscape painting, along with violet in shadows. So the white markings are a fooler – they change the outline and look like highlighted separate objects when you look away. The orange looks like a red rock partly in shade – and the dark limbs eliminate a signal “this is a quadruped, chase it.” That might be a red rock, inedible and not worth your time.

  3. 4 Mark Robinson 03/05/2012 at 5:01 am

    Robert is right in that what we humans experience as colour is as much a psychological phenomenon as a physical one. On top of that our vision system is very different from that of many (most?) animals, so what we see is not what they see.

    Something that appears to be red isn’t necessarily (and almost certainly isn’t) just reflecting light in the red part of the spectrum, but a range of frequencies which give us the overall impression of “red”. Other animals, even other people (see below), will experience something different when viewing the same object under the same conditions due to the different peak sensitivities of the colour-sensing cells in their eyes.

    Most artiodactyls and carnivorans are dichromats, having two types of cells which detect colour, usually one with a peak sensitivity in the blue part of the spectrum and the other in the yellow. Humans generally have three (and are therefore trichromats) with peak sensitivities in the deep-blue, blue-green, and yellow frequencies – not blue, green, and red as you might have assumed/heard/read somewhere. The gene that codes for the long-wavelength detecting pigment in humans is highly variable and some women, having two X-chromosomes and therefore two different forms of the gene, may actually be tetrachromats. Pigeons, surprisingly given their mostly dull colouring (to us, anyway!), seem to be pentachromats which must give them a superhuman ability to distinguish colour – presumably helpful in telling the difference between seeds in the dirt and dirt.

    An object reflecting only red light will appear red to us and grey or dull yellow to (say) a dog, depending on the actual frequency of the reflected light. An object reflecting strongly in the red part of the spectrum and weakly in the green and blue will still seem (bright) red to us but will be dark blue-green to a dog.

    The possible colours that an animal can be must also be informed by its diet in addition to selective pressures such as remaining hidden or impressing a potential mate. I suspect that orangey colours might work better on the forest floor where there is less light and a lot of the green has been filtered out through the foliage, whereas a lighter yellow might be better at concealing largish animals higher up in the understory. Smaller animals have less of a need to break up their outline and perhaps are better concealed by being a more uniform dull tree-colour.

    Ooh, sorry for the length – got carried away.

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