(above) Pink Flamingos at the Maryland Zoo, as depicted by reflected infrared light.
(above) Pink Flamingos at the Maryland Zoo (full color version)
Larger views of the images are available here
There is a similar reason for the flamingo’s pink appearance and also the high reflectivity of infrared light by their feathers as shown in the B&W version: the presence in their feathers of beta-carotene. Beta-carotene is present in both the algae and in the shrimp that are part of the flamingos’ diet. Beta carotene is an organic chemical that contains a reddish-orange pigment and is also highly reflective of IR radiation, explaining the light color of the flamingos’ feathers in the B&W image.
The equipment was a Nikon D100, Tamron 17-50 f2.8 lens, Hoya R72 IR filter. Exposure under bright sunlight of 1/30 sec at f2.8, ISO of 200.