The forthcoming issue of Rare Birds of Papua New Guinea has given us potentially 7 new species on stamps. However, realising that the image used for a Black Honey-buzzard was not as black as I would have expected, I searched for images of this species using Google. I soon found this photograph. I suggest that the designer/artist used this image to portray a Black Honey-buzzard, but he was wrong.
Using Google's image search of this particular photograph results in a suggestion by Google that the bird is an Oriental Honey-buzzard (Pernis ptilorhynchus). The photograph has been used in several places on the web, but perhaps the most authoritative was this one on Oriental Bird Images. This photograph was taken in January, 2009 at the Buxa Tiger Reserve, West Bengal, India, by Nikhil Devasar.
One is reminded of a similar error from PNG when an image of the South American Harpy Eagle was used in 2008 to portray a New Guinea Eagle (Harpyopsis novaeguineae).
I may just check for a few more source photographs...