been proposed to explain why these feathers have a green coloration: The nodules act collectively to produce constructive interference for yellow and blue radiation. These mix in the eye to produce the impression of green. The nodules act individually. The light passing through each nodule is dissipated by the melanin pigment. This attenuates the green and red portions of the visible light spectrum. The blue and yellow reflect with the light. The two hues then mix in the eye to produce green Conservation concern The African openbill stork is considered out of danger worldwide as it is abundant in various portions of its range. There are no current estimate for the total population numbers, but they appear to be quite stable. Although they are not currently threatened, they remain a large bird with low reproductive success meaning that human activities affecting their habitat could have a big impact on the species. Diet These birds primarily feed on aquatic snails of the genus Pila. They have been observed to also eat freshwater mussels. In different parts of their range, some individuals have been observed to eat terrestrial snails, frogs, crabs, fish, worms and large insects. It is important to note, that none of these are the preferred food choice of the African openbill. Foraging To forage for snails, the African openbill stands in shallow water, repeatedly dipping its beak in. They hold their bill slightly ajar and will snap it shut if they encounter a prey. Once they have a hold on the prey, they hold it with the tip of their mandibles and carry it back to shore. The storks will start slowly walking around and changing location, if they do not capture anything in the area they decided to forage in. The African openbill sometimes forages by standing on the back of hippopotamuses (Hippopotamus amphibius). As the hippopotamus wades through the vegetation, it upturns it and exposes the multiple snails that cling to the undersides of the plants. The stork will then feed on these exposed snails that have become easy prey. The hippopotamus does not seem to mind the presences of the bird on its back and is not harmed by it in any way. Lastly, very few individuals have been observed to forage visually from afar. There are accounts of African openbill storks swooping down from their nest and immediately securing a prey. This behavior is extremely