The ‘Feathered Lion’–Meet another African apex predator and conservation priority—the ‘crazy cool’ southern ground hornbill

The largest of the hornbills, SGHs forage on the ground in packs, may live 70 years, display memorable traits and have very specific habitat needs. 

Daybreak in the African bush. A deep, rhythmic, booming chorus of calls resonates through the forest. From their overnight roost in a tall tree, group members join in to announce their presence as territory holders. Like lions, but not mammalian at all. Avian, in fact—southern ground hornbills.

Bucorvus leadbeateri is the largest hornbill, standing one metre (40 inches) tall and weighing approximately four kilos, nine pounds, at adulthood—an apex predator that is one of the largest carnivorous birds in Africa. It is a charismatic and readily recognized flagship species of savanna biomes, a feathered icon of superlatives, uniqueness, cultural significance and conservation priority.

Southern ground hornbills—hereafter SGHs—are long-lived and have low reproductive rates. Their lives may span 70 years but, as obligate cooperative breeders, only the dominant pair of a group lays eggs. Groups of three to 12 birds hold vast territories of 100 to 250 square kilometres (38 to 96 square miles) in size, depending upon the habitat quality. To put that into perspective, the cities of New York and London span 753 and 977 square kilometres, respectively; if they were suitable habitat, each of these great cities could only host seven to 10 hornbill groups.

Matings may be up to nine years apart and produce only one young, which is then raised with the aid of non-breeding and immature group members. Most of these helpers are sons that have delayed their dispersals from the natal territory. They serve a lengthy apprenticeship and do not attempt to breed until reaching about 10 years of age, and only if they can establish dominance on a territory of their own. Daughters typically disperse earlier, and may spend a few years alone, in or between group territories, sometimes associating with groups of wild mammals for foraging success.

Seventy percent of an SGH’s day is spent on the ground, traveling as far as 10 kilometres, six miles, on the short toes of their terminal joints, which allow them to walk instead of hop, as other hornbills do. SGHs forage for anything they can catch, from invertebrates up to prey as large as hares. Diet preferences vary regionally. Birds in South Africa primarily eat invertebrates, in Kenya chameleons and snakes, and in Zimbabwe lots of frogs, especially during the nesting season.

Their massive beaks, driven by strong necks, stab, grasp, bludgeon and crush prey and dig like pick-axes as deep as 40 centimetres (16 inches) in dry conditions to extract toads. An SGH’s field of vision includes the tip of its own bill, affording precise, forceps-like gripping of smaller food items. Larger prey is hunted by the group as a pack, in mob fashion, with members joining in to rip apart the quarry. SGH groups follow herds of game and capture smaller game that is flushed. They’ve also been seen grooming warthogs for parasites, a rare interspecific behavior.

Although primarily predators, SGHs do occasionally scavenge and, rarely, eat fruit and seeds. Leopards, caracals and both martial and crowned eagles prey upon SGHs; nest predators include any creature capable of climbing trees, such as genets, leopards and snakes.

SGHs are also unique in the hornbill family in that they do not seal the female inside the nest, which is perhaps an adaptation to their intolerance for excessive heat. Neither is the nesting female constrained by a complete molt. Also unique among hornbills is that SGHs have 15 cervical vertebrae instead of 14, and the first two are fused, perhaps to aid their predatory lifestyle, which is so different from that of other hornbills.

Although SGHs occur in 16 countries in East, Central and Southern Africa, in 2010 the IUCN listed them as vulnerable overall because their numbers had decreased significantly outside of large protected areas. In 2014, SGHs in South Africa, Swaziland and Namibia were declared endangered because of severe declines in their range. They are the only one of nine African savanna hornbill species listed as “of concern,” at potentially high risk of extinction due to their extensive spatial requirements, naturally low densities and low reproduction rate.

Habitat

Habitat loss is the SGH’s greatest peril. Not only do the birds need large tracts of land, but also a variety of habitats: good-quality, open short-grass areas for foraging plus a mix of trees and low, open shrubland for shade. They need large trees for roosting at night, scattered so that they’re available wherever nightfall finds the group at the end of its foraging. For nesting, SGHs require deep hollows in big trees—enough of them to enable switching locations in case of nest predation.

These habitat needs expand and contract seasonally, but during nesting all of them must be found within about three kilometres (1.8 miles) of the nest, including trees big enough for the group to roost in within one kilometre of the nest. Suitable nesting trees may be used for 25 years or more and are the principal factor in determining the reproductive output of these magnificent birds. However, such trees are also important to other large birds—including owls, endangered martial eagles and critically endangered white-backed vultures—and they often occur in riparian areas that may be heavily used and damaged by humans and domestic livestock.

Myriad threats

Appropriate trees are also necessary for thermoregulation of the birds and their eggs. Thick walls in the nesting cavity must buffer against heat, as prolonged exposure to temperatures above 41°C (106°F) is fatal to embryos and chicks. An adult SGH’s enormous bill and facial and throat skin can dissipate up to 75% of its basal metabolic rate, but persistent high temperatures, especially if shade is limited, can kill adult birds, limit their foraging or force them to migrate to cooler areas of more rainfall. Daily maximum temperatures across Southern Africa have climbed over the past three decades and are predicted to rise further, requiring even more protection for SGHs.

Monoculture crops, soil compacted from overgrazing, wildfire, bush encroachment, deforestation, trees lost to elephants, honey-harvesting and illegal logging, slash-and-burn agriculture, unsustainable utilization of baobab trees, increasing CO2 levels and air temperatures coupled with erratic rainfall and changes in land management also contribute to SGH habitat loss.

If the birds see their reflections in the windows of rural buildings, territorialism spurs them to attack these “competitors” with their powerful bills, which are capable of killing puff adders and hares. But instead of vanquishing rivals, they break the windows. In Zimbabwe, 19 of 23 schools and 11 other buildings surrounding Matobo National Park had their lower windows smashed by SGHs. In retaliation, the birds are often shot or stoned, or their nests are burned, and birds may be injured by shards of glass. Fortunately, this behavior can be mitigated by painting the windows a non-reflective color or adding shade cloth.

Poisoning kills SGHs secondarily through the indiscriminate use of agricultural pesticides, including avicides meant to kill red-billed queleas that feed on grain crops. (Quelea carcasses are too small for vultures to bother with, but, although SGHs do not primarily eat carrion, they will scavenge them.) SGHs also eat poisoned baits intended to control rabies. Since the birds forage together, poisons typically affect all group members. Lead poisoning from spent ammunition also can occur, in one notable instance when a group of SGHs fed on a porcupine that had been killed with a shotgun, which left shot pellets throughout the carcass.

(In hunting areas, this is less likely, as bullets or fragments thereof typically remain in the carcass, which is usually brought to a skinning shed. Nonetheless, especially in South Africa, where a relatively high volume of game is shot, lead-free ammunition should be used whenever possible.)

Finally, spraying for tsetse flies can lead to more habitat loss as this opens up previously inhospitable areas to human settlement.

SGHs are also caught in snares as they follow game trails while foraging. In combat areas, antipersonnel mines pose a threat when the birds dig for food. Their inquisitive nature leads them to peck around transformer boxes, too, where live wires may electrocute them. Rural people may persecute SGHs for killing poultry and small pets and for raiding beehives. Since road verges can be profitable foraging areas, they often become roadkill themselves. Some airports kill or haze them because they threaten planes by feeding in the open grassy areas around runways. And, finally, the illegal trade in wildlife, for traditional medicine, ritual practices, zoos or hobbyists, can endanger their numbers as well.

Cultural icons

SGHs figure prominently in a wide variety of traditional cultures. Some communities revere the birds and protect them; others avoid them, utilize them illegally or outright maltreat them. SGHs may protect against witchcraft and evil spirits, or they may enable them. Both sets of beliefs bear on SGH conservation, but neither has been well studied.

Some cultures regard SGHs as timekeepers whose calls announce the beginning and sometimes the end of the workday, which can be useful when cloud cover makes it difficult to discern the hour. SGHs may also foretell seasonal changes through their movements. In Kenya and Tanzania, for instance, their behaviors signal the start of the dry season, when it’s time to move the cattle. In the southern parts of their range, they may herald the wet season. Malawians look to them for a sign to start preparing their fields, while Zambians believe it won’t rain while SGHs are still on their nests.

To some cultures, harming an SGH is like harming a family member, and they may bury a dead bird with full funeral rites. Others view them as benefactors who clear areas of snakes and scorpions. Baobabs, a preferred SGH nesting tree in Zimbabwe, have a high incidence of lightning strikes; once a tree is struck, it becomes sacred—the wood may not be used for fuel, fencing or buildings, and some communities may not even take honey from it. This helps protect nesting cavities for SGHs and may have given rise to one of the bird’s colloquial names: thunderbird.

Other cultures believe the thunderbird can protect them from lightning or bring rain during drought, but this requires mixing its feathers and feet with plant parts and animal fat and smearing the concoction on their homesteads. In South Africa and Mozambique, SGHs may be used ritualistically in song and dance—the whole bird or parts of it suspended in branches overhanging riverbeds and guarded by members of the community until enough rain has fallen.

Some cultures associate SGHs with death and kill them because they bring death, bad news or calamities; or they are simply avoided—no hazing, killing or even picking up of shed feathers—so as not to invite misfortune.

Because SGHs hunt without the aerial vantage point of raptors, many people believe that they can enable a different way of seeing, a “superpower” to find honey or game, or to foresee the arrival of debt collectors or enemies. A bit of SGH ashes placed under one’s tongue or sniffed before going to sleep is said to convey such abilities. And, because of their deep voices, some cultures in South Africa believe that placing the head of an SGH in one’s bath water will provide authority and make the community perceive that person differently.

SGH conservation

The largest, longest-running organized conservation efforts for SGHs, such as the Mabula Ground Hornbill Project, are in South Africa. There, research, education, awareness and threat mitigation have greatly increased the breeding rate of these imperiled birds, in part by capitalizing on an aspect of their natural reproductive strategy.

SGHs lay two eggs, but only one chick (usually the older) survives past the first few weeks of life. The Mabula Project perfected the introduction of these second, normally doomed nestlings into the wild, a years-long process that begins with hand-rearing and includes acclimating the juveniles in “bush school”—and also providing nest boxes where natural tree cavities are lacking. Some of these boxes now fledge one chick approximately every three years. At first, the boxes were found to increase nesting success, but when SGH groups reach and then exceed the average numbers for that region, reproductive success decreases. This may be due to foraging constraints or social conflicts. So, while nest boxes are suitable substitutes for trees to some extent, ultimately large tracts of natural habitat maintain optimal breeding densities better. Since more than half of South Africa’s SGH population resides only in a 7,523-square mile (19,484 square kilometres) area encompassing parts of Kruger National Park and surrounding conservation areas, there is great need to develop conservation strategies to foster more of these birds country-wide.

There is a direct relationship between home-range size and SGH breeding, or attempts to breed. Larger territories are more likely to supply the varying food needs. It is worth noting that this varied diet, plus the large tracts of diverse habitat that are needed to supply it, may make the species more resilient to climate change. Naturally, conservation of such expansive territories benefits all other species too, from vultures to wild dogs.

Remote wilderness hunting blocks also support these habitat needs. For example, 20% of Tanzania’s land mass is designated as such, and these lands are supported by the hunting programs of 45 outfitters currently operating in 85 blocks. Recent government game counts in the Katavi-Rukwa Ecosystem, an expanse of 19,953 square kilometres (7,704 square miles) where several hunting reserves buffer a national park, found that SGH distribution is robust and widespread there. They are also found in the surrounding unprotected areas, but these are experiencing more and more livestock, agriculture, settlements and tree-felling. Similar trends are apparent in Tanzania’s Selous-Mikumi Ecosystem. And in Zimbabwe, where the highest number of SGH sightings occur, the largest family groups and numbers of chicks occur in protected areas, not farmland.

Land that benefits all wildlife

Game reserves designated for hunting tourism maintain a diverse array of ecotypes that are best suited to support wildlife. They leave riparian areas intact, are free of electric-utility development, contain no or few human communities and their associated hazards, and are often marginal, tsetse fly-infested lands unsuitable for farming, livestock or photographic tourism. In other words, they’re perfect for SGHs.

This is a highly successful utilization model. These large blocks of land can be supported financially by a relatively small number of hunting clients, for whom the outfitters need not provide significant, land-altering infrastructure. Hunted species of wildlife in these areas can be managed sustainably as a renewable, valuable natural resource, and the revenue generated from them allows governments to reserve these lands for such use. And finally, virtually every species of flora and fauna benefits from hunting tourism, not only the imperiled SGH.

A grim future—perhaps

It is estimated that this remarkable bird may experience a population decline of 75% in the next 75 years, primarily due to habitat loss. Only protected populations are predicted to grow or remain stable. Protected areas that include game reserves and other lands designated for hunting are unequivocally the cornerstone of effective SGH conservation. In many countries, national parks, valuable though they be, are now numerous enough that many struggle to attract enough visitors to meet their financial needs. Furthermore, many of the landscapes most desirable to ordinary tourism have already been made into parks.

Just as a medley of habitats is required to support biodiversity, so is a variety of funding sources and models. Connected networks of national parks, government-controlled hunting lands and private lands dedicated to wildlife conservation are the ultimate scenario for the success of the SGH—and every other wild species.

Anti-hunting and animal-rights activists who push to end hunting directly or through bans on trophy imports must understand that if they succeed, hunting concessions, these absolutely essential reservoirs of habitat, will likely convert to human settlement once they are no longer economically viable through hunting. Although many uninformed people think stopping hunting tourism will save animals, the reverse is true; instead, wildlife, including the southern ground hornbill, will inevitably be lost via the conversion of their habitats. If you care about conservation, please reject the protectionist rhetoric. The maintenance of biodiversity is a critically important, ecologically sound and even beautiful goal that everyone must embrace, as it benefits humans as well as Nature.

Southern ground hornbills are key indicators of natural and anthropogenic effects on their landscapes. Some cultures refuse to kill them for fear of unleashing catastrophic downpours. Some feel that they can alter our perceptions and make us view things differently, or afford us a more authoritative voice. If the thunderbird is allowed to fade away, never to be heard again due to habitat loss, devastating downpours of biodiversity loss will follow. May their continuing presence in large, protected wild areas allow us to see challenges and realities with greater acuity and impart stronger voices to all of us engaged in conservation efforts.

Karen Seginak is a wildlife biologist with 30 years’ (and counting) experience in various field studies. She is also a traveler, photographer, hunter, angler and writer who is keenly interested in biodiversity and all models that help to sustain it. Her most recent article in Conservation Frontlines was “Meet the Mule, ‘Domestic Facilitator’ to Wilderness Experiences,” in October 2020. Photographer John Luyt is a photo and safari guide at Duke Safaris in South Africa.  

Banner image: South African southern ground hornbill—a female, identified by her dark-blue throat patch. John Luyt photo