When I first saw this set of 4 WWF stamps featuring the Greater Kudu (Tragelaphus strepsiceros) I noticed the oxpeckers on one stamp, and hoped they would be Red-billed as Yellow-billed had appeared on a Buffalo stamp issued in 2001 and the SAPOA issue of 2007. I have not been able to find the source photograph for this stamp, and most of the oxpeckers are indistinct, however at least 3 of the birds show the characteristic light eye of Red-billed Oxpecker (Buphagus erythrorhynchus), particularly the one on top at the back. I shall add this on my next update.