Ground-hornbills pair for life but have a cooperative breeding strategy with helpers assisting in the feeding of dependent young. Unfortunately they have an amazingly low productivity; observations in South Africa show that on average only one chick is reared to fledging every 9 years (Kemp, 1995)!
It takes a chick at least 6 years to reach maturity and though long-lived these bird are clearly very susceptible to any form of disturbance!