Dakota McCoy and colleagues measured reflectance in several birds-of-paradise in 2018 and found values below 0.1 percent at some angles, comparable with engineered super-black materials. The mechanism is geometric. Barbules in these feathers are arranged in curved, vertically tilted arrays that trap incoming light in a forest of microstructures, scattering it repeatedly until it is absorbed. Ordinary black feathers, by contrast, reflect a few percent.
The function appears to be contrast. The super-black patches sit directly beside the intensely coloured breast shield, and the absence of any specular highlight removes the visual cues an observer would normally use to judge shape and depth. The coloured patch reads as brighter and less anchored in space than it is.
The taxonomy has moved. The birds long called the superb bird-of-paradise are now generally split into more than one species within Lophorina, so material published under the old single name may refer to different birds.