Southern Ground-Hornbills can live for up to 60 years but may take years to raise a single chick. Across the Greater Kruger, artificial nests, long-term science and cooperation are helping to change the odds for one of South Africa’s most threatened birds.
Before sunrise, a deep, booming call rolls across Thornybush.
It can travel for kilometres. You may feel it before you see the bird responsible: almost a metre tall, dressed in black and marked by vivid red facial skin.
The Southern Ground-Hornbill is one of the bushveld’s most commanding birds. It is also one of its most vulnerable.
With fewer than 2,500 mature birds believed to remain in the region, the species is classified as regionally Endangered in South Africa. Its recovery depends not only on protecting birds, but on protecting something increasingly difficult to find: a safe place to raise the next generation.
At Thornybush Nature Reserve, one natural nest and one artificial nest form part of a conservation story stretching across the Greater Kruger
Southern Ground-Hornbills at a glance
Southern Ground-Hornbills are the world’s largest cooperatively breeding birds. They live in close family groups, usually made up of a dominant breeding pair and several helpers, often male offspring from previous seasons.
Raising a chick becomes a family affair.
While the female remains at the nest, other members of the group:
- search for food;
- deliver meals to the female and chick;
- watch for predators;
- defend their territory; and
- help care for the young bird after it leaves the nest.
The female generally lays two eggs several days apart. The first chick hatches earlier and quickly gains an advantage, which means the second chick seldom survives.
The remaining chick spends approximately 80 to 90 days in the nest, entirely dependent on its family. Even after fledging, there are no guarantees. Young birds mature slowly, suitable territories are limited and a breeding group may wait years before successfully raising another chick.
For a species that reproduces at this pace, every successful nest matters.
The problem: you cannot raise a chick without the right nest
Southern Ground-Hornbills do not build conventional nests. They need large, deep cavities found in mature trees, rock faces or earth banks.
Those cavities are becoming increasingly scarce.
As landscapes change and old trees disappear, even healthy bird groups may find themselves without a suitable place to breed. Protecting habitat remains essential, but these long-lived trees and the cavities within them, cannot be replaced overnight… That is where artificial nests come in.
Can an artificial nest really make a difference?
Yes, when it is carefully designed, correctly positioned and continually monitored.
The APNR Southern Ground-Hornbill Project currently monitors approximately 35 nesting sites across the Associated Private Nature Reserves. Only five are natural. The others are purpose-built artificial nests.
These are not simply wooden boxes placed in trees. Researchers must consider:
- the position and height of the nest;
- protection from predators and extreme weather;
- internal space for a growing chick;
- ventilation and temperature;
- durability; and
- whether the breeding group will accept and reuse it.
The nests are inspected, repaired and improved as researchers learn more about the conditions Southern Ground-Hornbills need to breed successfully.
The results are remarkable.
What is the APNR Southern Ground-Hornbill Project?
Established in 2000, the project is a long-term research and conservation programme operating across the Associated Private Nature Reserves, or APNR.
The APNR includes five private nature reserves along the western boundary of Kruger National Park:
- Thornybush Nature Reserve;
- Klaserie;
- Timbavati;
- Umbabat; and
- Balule.
With internal fences removed, wildlife can move through this connected Greater Kruger landscape. Conservation work can move across those boundaries too.
In partnership with the FitzPatrick Institute of African Ornithology at the University of Cape Town, the project monitors Southern Ground-Hornbill groups, studies their behaviour and breeding success, and provides artificial nesting sites where natural cavities are limited.
This connected approach is vital. A Southern Ground-Hornbill territory can cover hundreds of square kilometres, so no single reserve can protect the species in isolation.
Thornybush Nature Reserve’s place in the bigger picture
Thornybush Nature Reserve contributes two active sites to the APNR monitoring network:
- one natural nest; and
- one artificial nest.
On a map, they may appear to be only two small points. For researchers, each one can provide years of valuable information.
Nest monitoring helps answer important questions:
- When does breeding begin?
- Do groups return to the same nest?
- How quickly are chicks developing?
- How often does a breeding attempt succeed?
- How do rainfall and extreme temperatures affect the birds?
- Where do young birds go when they leave their family group?
One ringed bird that fledged in the APNR in 2011 was later recorded approximately 40 kilometres away, where it joined another breeding group.
A chick raised in one reserve can therefore contribute to the recovery of the species far beyond the territory in which it hatched.
The science happening inside the nest
Researchers are not simply counting chicks. They are studying the conditions that give those chicks the best possible chance of survival.
Temperature sensors record how conditions inside nests change during the day. Camera traps capture feeding behaviour. Measurements taken at different stages show how quickly nestlings are growing and whether heat is affecting their condition.
Researchers also observe how adult birds divide their time between:
- finding food;
- watching for danger;
- feeding the nesting female and chick; and
- seeking shade during periods of extreme heat.
This research is helping to guide the next generation of artificial nests, including designs that may offer better protection as temperatures rise.
For a bird that can live for 50 to 60 years, conservation cannot be measured over one summer. Meaningful patterns only emerge when the same groups, territories and nesting sites are followed over decades.
From one nest to a national recovery effort
The knowledge gathered within the APNR contributes to South Africa’s Southern Ground-Hornbill Species Action Plan and Reintroduction Plan.
The project also supports the work of the Mabula Ground-Hornbill Project, which establishes new breeding groups in areas where the species once occurred.
Because the second-hatched chick would seldom survive naturally, it may be collected under strictly managed specialist protocols. These chicks can be carefully reared and later considered for reintroduction programmes.
In this way, one monitored nest can contribute to something much larger:
research → better nest design → improved breeding success → stronger wild populations → carefully managed reintroductions
The call that carries
Southern Ground-Hornbill conservation is not defined by a single nest or one successful breeding season.
It is found in artificial nests maintained through the summer heat. In chicks measured from hatching to fledging. In ringed birds identified years later. And in knowledge shared across reserve boundaries.
At Thornybush, one natural nest and one artificial nest are part of that long, patient work.
For a bird that may take years to raise a single chick, each viable nest offers something immensely valuable: another chance.
And when that unmistakable call rolls across Thornybush before sunrise, it carries more than sound through the bushveld.
It carries hope.
