Sunbittern

When a sunbittern is threatened by a predator or perceives a serious threat near its nest, it suddenly spreads both wings wide and raises them, revealing two large, brightly coloured concentric patterns in chestnut, orange, gold, and black on the wing surfaces that together strongly resemble a pair of huge eyes or the face of a large animal. This is a classic deimatic or startle display, intended to briefly frighten or confuse a predator into hesitating or retreating, giving the sunbittern, or its chicks, a chance to escape, and the transformation from a slim, well-camouflaged bird into this large staring face is abrupt and dramatic enough to be genuinely effective against many would-be attackers.

Its single closest living relative is the kagu, a flightless or nearly flightless grey bird found only in the forests of New Caledonia, a Pacific island east of Australia, despite the sunbittern itself living in Central and South America on the other side of the world. The two species are the only members of a small, ancient lineage of birds, and their enormous geographic separation combined with their close relationship is generally explained by both being remnants of a group that was once far more widespread, with most other members having gone extinct, leaving these two isolated survivors on distant continents.

There are documented observations, including from captive birds, of sunbitterns practising a form of bait fishing, in which the bird places a small object such as a feather, an insect, or a scrap of food onto the surface of the water and then waits, striking at any fish that approaches to investigate the lure. This behaviour is considered a genuine, if occasional, example of tool use, a capability once thought to be limited to a small number of birds such as certain crows and herons, and it demonstrates that the sunbittern is capable of the flexible, problem-solving foraging behaviour that tool use requires.

For the great majority of the time, the sunbittern relies on camouflage rather than its startle display. Its plumage is finely barred and mottled in greys, browns, and blacks that closely match the broken patterns of light, shadow, leaf litter, and bark along the forested stream banks where it forages, and it moves slowly and deliberately, freezing when it senses danger. A motionless sunbittern with its wings folded is remarkably difficult to spot, and the dramatic eyespot display is held in reserve as a last resort for when camouflage has already failed and a predator is closing in.