The breeding season of the Southern Ground Hornbills lasts from October to December each year and the breeding pair builds their nest together. The nest is built in natural cavities in cliffs or in living or dead trees. The nest is lined with dry leaves and grasses and is open-fronted, allowing for convenient entry and exit.
A shrinking natural habitat has seen the decrease of the species, with only an estimated amount of 1500 Southern Ground Hornbills left in South Africa in February 2014. The Joburg Zoo has taken conservation of the species into their own hands by hand-rearing three birds and teaching them social skills so that they can successfully interact and breed with other birds. In collaboration with other organizations, the long-term project removes the chicks that have been abandoned by the breeding pair from the nest and rescues them.
Ground hornbills seem to be connoisseurs of accommodation, and have taken advantage of artificial nest sites scattered throughout the Associated Private Nature Reserves (APNR) adjoining the Kruger National Park. Over the last ground hornbill breeding season 11 of 26 known nests were occupied by ground hornbills. Out of these fledged eight nestlings, seven of which emerged from artificial nests constructed from massive hollowed-out logs.
The average weight of these artificial nests is 250kg. The nests were erected as part of a research project that began in 2002. The science behind the project is monitored by the Percy Fitzpatrick Institute at the University of Cape Town, with Professor Morné du Plessis coordinating the research. With the support and assistance of the landowners and staff of the APNR and the financial assistance of Dow Chemicals, much new information has been revealed about ground hornbills.
Du Plessis says that it is too soon to tell if it is simply the influence of the artificial nests that has produced this "exceptional" breeding season, or if last year's rainfall patterns increased the amount of food available in the area around the artificial nests. The three nests which failed to fledge chicks were located in the north of the APNR, which had less rainfall than the southern areas where the chicks fledged from. He is hoping that future research will consolidate existing knowledge of what drives a successful breeding season.
Breeding groups that had access to artificial nests did not require a large proportion of open woodlands, whereas those that occupied natural nests depended on large surrounding woodlands for successful breeding. Breeding pairs that had a higher amount of helpers were more successful than those who only consisted of 2 or 3 birds. The breeding performance of the ground hornbill can therefore be attributed to the existence of open woodlands, sufficient rainfall, a larger group size and the assistance of helpers.
At this time a field researcher, Ziggy Rode, will be teaming up with Dr Alan Kemp from the Fitzpatrick Institute to try and develop a capture technique for ground hornbills. The ultimate aim is to fit a satellite-tracking collar on one adult bird from at least five groups of ground hornbills, so that much more in-depth knowledge of the species can be obtained. However, the cost of doing this is estimated to be in the region of R60, 000 per year, and the du Plessis says that they are looking at ways of bringing the costs down.
"A lot of funding is required for these more sophisticated techniques that are used on larger mammals, and this is stretching our budget." Du Plessis says that although fire and elephants play a role in the removal of large trees that provide suitable nesting sites for ground hornbills, human activity is a major factor. The removal of large dead trees such as leadwoods, which people sometimes regard as ecologically "useless", for use in houses and lodges has been a major blow to the ground hornbill housing situation.
Hoedspruit Endangered Species Centre
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Johannesburg City Parks and Zoo