Disruptive coloration

's 1940 Adaptive Coloration in Animals, "showing the distractive effect upon the eye of patterns which contrast as violently as possible with the tone of their background". The examples are of a fish, an antelope, and a bird. The artist Abbott Handerson Thayer in his 1909 book Concealing-Coloration in the Animal Kingdom argued that animals were concealed by a combination of countershading and "ruptive" marks, which together "obliterated" their self-shadowing and their shape. Thayer explained that: Hugh Cott's 1940 book Adaptive Coloration in Animals introduced ideas such as "maximum disruptive contrast". This uses streaks of boldly contrasting colour, which paradoxically make animals or military vehicles less visible by breaking up their outlines. He explains that in ideal conditions, background colour matching together with countershading would "suffice to render an animal absolutely invisible against a plain background", but at once adds that conditions are hardly ever ideal, as they are constantly changing, as is the light. Therefore, Cott argues, camouflage has to break up the perceived continuous surfaces of an object and its outlines. In his own words, "for effective concealment, it is essential that the tell-tale appearance of form should be destroyed." He draws an analogy with a pickpocket who carefully distracts your attention, arguing that: Further, Cott criticises unscientific attempts at camouflage, early in the Second World War, for not understanding the principles involved: The pioneering work of Thayer and Cott is endorsed in the 2006 review of disruptive coloration by Martin Stevens and colleagues, which notes that they proposed a "different form of camouflage" from the traditional "strategy of background matching" proposed by authors such as Alfred Russel Wallace (Darwinism, 1889), Edward Bagnall Poulton (The Colours of Animals, 1890) and Frank Evers Beddard (Animal Coloration, 1895); Stevens observes that background matching on its own would always fail because of "discontinuities between the boundary of the animal and the background". ==In animals==

, Caprimulgus aegyptius, rests on the sand, protected by its coloration, immobility, and concealment of shadow as it faces the sun. Disruptive patterns use strongly contrasting markings such as spots or stripes to break up the outlines of an animal or military vehicle. Some predators, like the leopard, and some potential prey like the Egyptian nightjar, use disruptive patterns. Disruptive patterns are defined by A. Barbosa and colleagues as "characterized by high-contrast light and dark patches, in a nonrepetitive configuration, that also provide camouflage by disrupting the recognizable shape or orientation of the animal", as in the cuttlefish. , Oxybelis aeneus, conceals its eye with a coincident dark stripe, contrasting with its pale underside. The strategy appears paradoxical and counter-intuitive as a method of camouflage, since disrupting outlines depends on using patches of colour which contrast strongly with each other, so the patches are themselves conspicuous. While background matching works best for a single background, disruptive coloration is a more effective strategy when an animal or a military vehicle may have a variety of backgrounds. The opposite case: aposematism , Salamandra salamandra, advertises its inedibility with bright warning colours, in patches that emphasize its body shape. Many poisonous or distasteful animals that advertise their presence with warning coloration (aposematism) use patterns that emphasize rather than disrupt their outlines. For example, skunks, salamanders and monarch butterflies all have high contrast patterns that display their outlines. These advertising patterns exploit the opposite principle to disruptive coloration, for what is in effect the exactly opposite effect: to make the animal as conspicuous as possible. Some Lepidoptera, including the wood tiger moth, are aposematic and disruptively coloured; against a green, vegetative background their bright aposematic coloration stands out, but on the ground their wings camouflage them among dead leaves and dirt. A disputed case: the giraffe The presence of bold markings does not in itself prove that an animal relies on camouflage. According to Mitchell, adult giraffes are "inescapably conspicuous", making the conclusion that their patterns are for camouflage appear counterintuitive: but when standing among trees and bushes, their camouflage is effective at even a few metres' distance. Polygonia c-album avoids a typical butterfly shape. Further, young giraffes are much more vulnerable to predation than adults: between 60% and 75% of calves die within a year. Mothers hide their calves, which spend much of the time lying down in cover. Since the presence of a mother does not affect survival, Mitchell suggests that young giraffes must be extremely well camouflaged. This is supported by the fact that coat markings are strongly inherited. Conversely, far from hiding, adult giraffes move about to gain the best view of an approaching predator, relying on their size and ability to defend themselves even from lions. Other ways of hiding outlines The outlines of an animal's body can be made hard to see by other methods, such as by using a highly irregular outline. For example, the comma butterfly, Polygonia c-album, is highly cryptic when its wings are closed, with cryptic colours, disruptive pattern, and irregular outer margins to the wings. ==In plants==

plants, such as the saw greenbriar, Smilax bona-nox, are variegated with pale markings which may serve as camouflage. ==Military usage==

Disruptive coloration is common in military usage, for military vehicles, for firing positions and other installations, and for individual soldiers, where uniforms, equipment such as helmets, and face paint may be used to break up outlines and features. Disruptive coloration, however, does not always achieve crypsis on its own, as an animal or a military target may be given away by other factors including shape, shine, and shadow. Many military camouflage patterns since the 1940s have been disruptively coloured, and with the issue of US Woodland pattern to United States armed forces from 1981, disruptive pattern became a dominant feature of military uniforms. From 1969, Disruptive Pattern Material (DPM) began to replace plain material for uniforms in the British Armed Forces and was later used by many other armies. Challenges 1990 is a non-digital pattern designed to disrupt outlines at various distances. Three major challenges face the design of disruptively patterned uniforms. Firstly, units frequently move from one terrain to another, where the background colours and contrasts may differ greatly. A uniform designed for woodland will be too strongly contrasting for desert use, and too green for urban use. Therefore, no single camouflage pattern is effective in all terrains. The American UCP of 2004 attempted to suit all environments but was withdrawn after a few years of service. Terrain specific patterns like "Berlin camouflage", which was applied to British vehicles operating in Berlin during the Cold War, have sometimes been developed but are ineffective in other terrains. Secondly, the effectiveness of any pattern in disrupting a soldier's outlines varies with lighting, depending on the weather and the height of the sun in the sky. And thirdly, any given patch of printed colour varies in apparent size with distance from the enemy observing the pattern. A pattern printed with small patches of colour blends into a single perceived mass at a certain range, defeating the disruptive effect. Conversely, a pattern printed with large patches of colour appears conspicuous at shorter ranges. This problem has been solved with pixellated shapes, often designed digitally, that provide a fractal-like range of patch sizes, enabling them to be effectively disruptive both at close range and at a distance. The first genuinely digital camouflage pattern was the Canadian CADPAT, soon followed by the American MARPAT. A pixellated appearance is not essential for this effect, though it is simpler to design and to print. ==Examples==

File:WoodFrog DarienLakesStatePark 2020-06-16 (02).jpg|Wood frog among fallen leaves File:Great male Leopard in South Afrika-JD.JPG|alt=photo of a leopard|Leopard: a disruptively camouflaged (and countershaded) predator File:Ptarmigan and five chicks.JPG|alt=photo of a hen ptarmigan and her chicks|A ptarmigan and five chicks with exceptional disruptive camouflage File:Jumping spider with prey.jpg|alt=photo of a jumping spider|Jumping spider: a disruptively camouflaged invertebrate predator File:Armoured personnel carriers, Eriboll - geograph.org.uk - 1316295.jpg|alt=photo of armoured vehicles easy to see on bare hillside|"Shape, shine, shadow" make these "camouflaged" military vehicles easily visible, their outlines not disrupted. File:Challenger 2 Tank MOD 45148907.jpg|alt=photo of a Challenger 2 tank at speed on grassy plain|A British Challenger 2 tank painted in bold disruptive pattern of sand and green File:Chaetodon striatus Brasil.jpg|The banded butterflyfish, Chaetodon striatus, has strong disruptive bands through the body and concealing the eye. File:US Navy WWII ship camouflage measures - detail of USS Alabama in measure 16.jpg|USS Alabama wearing Measure 12 ship camouflage during World War II File:A-7D Corsairs 354th TFW at Korat 1972.JPG|Disruptively camouflaged A-7D Corsairs on a disruptively painted concrete surface, Thailand, 1972 ==References==