The southern ground-hornbill or Buvorcus leadbeateri is a type of ground hornbill found in South Africa, Namibia, Botswana, Zimbabwe, Zambia, Mozambique, Malawi, Angola, Democratic Republic of the Congo, Rwanda, Burundi, Kenya, Uganda and Tanzania. They live in large, fiercely defended territories spanning 100-250 square kilometers. These cover savana, grassland and open woodland, but the southern ground hornbill prefers open area with short grass for foraging. They are found south of the equator, but have small territorial overlaps with another species of ground-hornbill, the Norther (Abyssinian) ground-hornbill, found north of the equator. Southern ground-hornbills are also often found near water holes and drainage lines, not because they need water but because they use them as corridor links between populations and because of the rich prey diversity and large nesting trees.
The Southern and Abyssinian ground-hornbills are the only species in the genus Bucorvus, in the family of Bucorvidae. Bucorvidae diverged from their cousins, Bucerotidae, when they left Africa and spread towards South Asia, South East Asia, and Australasia. They are different in that Bucorvidae females do not seal themselves inside their nest and have a head more designed for suppressing live prey than insects and plants.
Southern ground-hornbills use this adaptation to eat a variety of animals, including insects, arachnids, snakes, lizards, tortoises, frogs, small birds, and small mammals up to the size of a hare. They will also eat carrion and occasionally fruit and seeds, and have been seen eating parasites from African warthog skin. They hunt most of their prey on the ground, even though they are strong flyers, and spend an average of 70% of their day walking, or when food is abundant, playing. They usually travel between 6-8 km per day around their nest and use their full territory during the winter.
Southern ground-hornbills have the largest cooperative breeding groups of a bird species in the world. Their groups consist of one dominant male and female and many non-breeding male helpers. These are usually earlier offspring that have delayed leaving their home territory. Since raising chicks is very demanding, the southern ground-hornbill needs all wings on deck. Only one female, the alpha, is tolerated in the group. This female and her group will find a large, natural cavity in a tree or rock face. They are able to make some modifications but mostly rely on already occurring cavities, so they will use the same one repeatedly. Unlike Bucerotidae, the female will not seal herself in the cavity. She will sit on her eggs for 42 days and brood the hatchling for 30 days. Because she can only leave for short periods, the males will care for the female and the chick, as well as bringing leaf material for the nest.
Southern ground-hornbills nest for a long time (between September and December) and do not produce many chicks, partly because there are often several years between breeding. Another reason is that although 80% of the time two eggs are laid, the second one is laid a few days later and is thus younger and weaker. The older chick will then outcompete the younger one, and the parents ignore the second chick and will most likely die of dehydration. It is thought that the younger chick is simply an insurance policy. Breeding and brooding takes about half the year.
Image courtesy of the Mabula Ground-hornbill Project
The southern ground-hornbill are continentally Vulnerable, but in South Africa and Namibia they are classified Endangered, where it has vanished from up to 70% of its natural range. Much of the southern ground-hornbill’s range has been changed by human expansion, over-grazing and climate change, all of which also fragment toe ground-horbill’s range. This has resulted in the loss of bush and large trees needed for nesting. Without these trees less chicks are hatched and the population destabilized.
Another threat to the southern ground-hornbills is poisoning from eating caracsses that have been either deliberately poisoned to kill other carnivores or who have been unintentionally poisoned by lead bullets. The ground hornbills can also be poisoned by pesticides meant to kill the Red billed Quelea, a crop eating bird.
They are also targeted by humans because they break glass in mirrors, windows and vehicles because they believe they are fighting an intruder (their reflection). As this results in damage to people’s property, they can be killed for this. They are very rarely hunted as traditional medicine and their feathers, which are thought to cause rain in drought years. Since they like open areas they are prone to being hit by cars. Southern ground-horbill’s slow reproduction rate also contributes to population decline. It is thought that only one chick grows to an adult every nine years. Because of these factors, there are only about 1,500 southern ground-hornbills and only 400-500 breeding groups found in South Africa.
The southern ground-hornbill is culturally important because they are believed to be rainbirds and are thought to bring the thunder and rain. The Mabula Ground Hornbill Project, an organization created to help protect this species, has several conservation methods in place. First, they supply people with ways to cover low windows and explain why the ground-hornbills are breaking their windows. They also have created an ideal fake nest for the species, and will place them in the territory of wild birds who don’t have a good nest site. The Project also tells people about the impact of poisoning and work to create useful alternatives. Fourthly, they work to insulate transformer boxes to prevent birds from being electrocuted. Another interesting project the Mabula Ground Hornbill Project is taking on is harvesting the second born chicks of nests. They then raise and release the unwanted chicks into established groups of rescued birds which are later released into areas without ground-hornbills, once threats have been reduced. They also work on educating the public about threats facing the Southern ground-hornbill.
About ground-hornbills. (n.d.). Retrieved January 18, 2021, from http://ground-hornbill.org.za/about-ground-hornbills
Conservation. (2019, July 11). Retrieved January 18, 2021, from https://mabula.com/conservation/
Image courtesy of the Mabula Ground-hornbill Project