The shadow cast on the light-colored underparts of a standing Black Turnstone helps to offset the contrast between the dark-colored upper and light-colored lower portions, making the bird appear flatter against the background, and more difficult to see. This effect would not work if the bird were light above and dark below, as demonstrated by the upside down individual in the figure, which is much easier to spot in its dark, rocky habitat. This pattern of dark above and light below is known as countershading, and is found in many species of birds.

Countershading in Black Turnstones

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