Birds
Southern Ground Hornbill
Bucorvus leadbeateri · also called southern ground hornbill
The southern ground hornbill is a turkey-sized black bird with a blood-red face that strides across the African savanna hunting snakes and tortoises. It can live 70 years, successfully raises a chick roughly once a decade, and booms at dawn loudly enough to be mistaken for a lion.
Overview
Southern ground hornbills live in savanna, woodland, and grassland of eastern and southern Africa, in open country with scattered large trees. About 90–130 cm tall, glossy black with a bare red face, they walk to hunt insects, snakes, tortoises, and small mammals.
A call mistaken for a lion
At dawn, groups give a deep four-note booming call, amplified by an inflatable throat pouch, that carries for kilometres and is often taken for a distant lion.
One chick a decade
A group raises just one chick to independence roughly once every nine years — among the slowest breeding of any bird — offset only by lifespans of 50 to 70 years.
Status
The southern ground hornbill is Vulnerable and decreasing, from habitat and nest-tree loss, poisoning, and persecution, with recovery slowed by its low breeding rate.
Southern Ground Hornbill: common questions
Why does the southern ground hornbill breed so slowly?
A southern ground hornbill group typically lays two eggs, but the second chick to hatch is smaller and is neglected and left to die within days, an insurance strategy in case the first egg fails, so at most one chick per breeding attempt is ever raised. On top of this, breeding attempts often fail entirely due to drought, predation, or lack of a suitable nest cavity, and pairs do not attempt to breed every year. The result is that a group successfully raises a chick to independence only about once every nine years on average, one of the lowest reproductive rates recorded for any bird, which means populations recover extremely slowly from any decline and are highly sensitive to added adult mortality.
Is the southern ground hornbill's call really mistaken for a lion?
Yes, regularly. At dawn, groups give a deep, far-carrying, rhythmic four-note booming call, produced with the help of an inflatable coloured throat pouch that acts as a resonating chamber, and the low pitch and volume of this call mean it carries for several kilometres across open savanna. People unfamiliar with the sound, and even experienced bush guides describing it to visitors, commonly note that a distant ground hornbill chorus is easily confused with the roaring of a lion, and the two sounds occupy a similar low frequency range, though the hornbill's call has a more measured, repetitive four-beat rhythm once you know what to listen for.
How long does a southern ground hornbill live?
It is one of the longest-lived birds, with individuals in the wild reaching 50 to 70 years of age, and captive birds have lived even longer. This exceptional longevity is closely tied to the species' overall life strategy, since a bird that reproduces as rarely as the ground hornbill does can only sustain a stable population if adults survive for a very long time and each breeding pair therefore has many decades of potential breeding attempts. The flip side is that this strategy leaves the species poorly equipped to cope with any human-caused increase in adult deaths, since lost adults cannot be quickly replaced.
Why is the southern ground hornbill Vulnerable?
Its populations are declining across much of its range, especially on farmland and communal land outside large protected areas, due to a combination of habitat loss and the felling of the big old trees it needs for nest cavities, secondary poisoning from carcasses laced with poison to kill predators, direct persecution including because the birds sometimes attack their own reflections in windows and break them, electrocution and collisions, and the removal of chicks from nests. Because the species breeds so slowly and lives so long, these losses of adult birds accumulate faster than reproduction can offset them, driving the ongoing decline that underlies its Vulnerable listing.