Ten years on, a re-introduction of southern ground hornbill on Mabula Private Game Reserve in the Limpopo Province of South Africa

Summary

The southern ground hornbill (Bucorvus leadbeateri), a cooperatively breeding bird that has lost up to half its former South African range, was the subject of a re-introduction begun in 1999 on Mabula Private Game Reserve in Limpopo Province, starting with three hand-reared birds from Pretoria Zoo. The project discovered that a rehabilitated, wild-caught alpha male would adopt, teach, and protect unrelated hand-reared juveniles introduced into his group, an unselfish behavior later confirmed when a second rehabilitated male briefly took over leadership before the original male returned and reclaimed the group. This dynamic let the Mabula group function as a training ground, preparing successive hand-reared juveniles, fitted with backpack transmitters and monitored daily for foraging skill development, for eventual release elsewhere in South Africa on reserves increasingly converted from cattle farming to eco-tourism. An artificial nest log was installed to compensate for a shortage of large cavity-bearing trees. By ten years in, the core group, a wild alpha male, a seven-year-old hand-reared alpha female, and a two-year-old hand-reared male, had been observed copulating and attending a nest, though breeding to independent chicks had not yet occurred, complicated by the species' late maturity (first breeding at six to eight years) and the female sometimes ranging up to 40 kilometres from the reserve after seasonal rains. A parallel captive-breeding program produced its first chicks in 2003, and a global studbook and genetic sampling program have since been established. The project rated itself Partially Successful, since breeding success at Mabula remains unconfirmed despite the encouraging social and behavioral groundwork laid.