Bob and Nancy are two rhinoceros hornbills at the Philadelphia Zoo. Both were hatched in 2007. On its head is a structure that takes up to six years to develop and resembles a smaller bill. It is called the casque and is mostly hollow. The birds are about 30 to 35 inches tall. That is considerably smaller than this colorful wall mural of the rhino hornbill near the entrance to the zoo in Philadelphia.
