Vultures have an un-feathered part of their face that can turn bright red. This face flushing is an important way for these birds to communicate things like their status in the group, kinda like a colour coded Facebook update for vultures!
http://www.sciencedaily.com/releases/2010/10/101006094045.htm
2010 is the Year of Biodiversity and Earth Rangers has teamed up with The United Nations Convention on Biological Diversity to bring you a daily dose of biodiversity basics