Southern Ground Hornbills

July 7, 2023
Paddy Pacey
Birds

This post falls into two sections:

The text and graphics of a BirdLife Zimbabwe presentation given by Peter Makhusa entitled “Where are our Ground Hornbills” at the Avondale Sports Club, on the 18th May, 2023.
A general description of the distribution, habits and conservation status of the Southern ground hornbill

1. Peter Makhasa’s Talk

About our Bird (the Southern Ground Hornbill)
Our Vision and Mission
Target Conservation Action Plan
Our Contact Information

(Peter Makhusa first became interested in Southern Ground Hornbills in 2019 when he encountered them around the Matobo Hills near Bulawayo.

He discovered that the hornbill population actually avoid the National Park where there is a high concentration of baboons that raid their nests. They actually feel safer living amongst the human population of the surrounding communal areas and co-exist with humans quite successfully.

They also find good nesting places amongst the rocks of the area, not so much in big trees, (where they traditionally nest.)

Why the Southern Ground Hornbill is important?

This charismatic species is both culturally and ecologically important. They are known across their sub-Saharan range as the thunder birds or rain birds. They are also a valuable flagship species for the savannah biome. They are easily recognisable and with such large spatial requirements, any successful conservation action in even one of their expansive territories benefits all the other savanna and grassland species, including threatened species such as vultures, wild dog and cheetah.

At present, Southern Ground-hornbills are considered internationally as “Vulnerable” throughout their sub-equatorial range in Africa by the IUCN. Within South Africa and Namibia they have already been classified as “Endangered”, with their numbers outside of formally protected areas still declining. Their populations continue to decline towards being “Critically Endangered” in South Africa.

The reasons for their decline are predominantly loss of habitat, loss of large nesting trees, as well as secondary poisoning, e.g. lead toxicosis from spent lead ammunition in carcases they feed on, and electrocution on transformers.

CURRENT SIGHTINGS

The red dots on the map shows the current sightings of the SGH in relation to the black squares which are the historical sites where they have been recorded. The white areas show where there is no data. You can see the gaps.

WHERE & WHEN DID YOU LAST SEE A GROUND HORNBILL?

POPULATION STATUS

The full population status of the Southern Ground Hornbill in Zimbabwe unknown.

There is a need to reach out to remote areas historically known to have healthy populations of SGH to understand and document the current national status accurately. Information dissemination and constant stakeholder engagement is key in our efforts to conserve this iconic species.

There is an urgent need to assess the population of the Southern Ground Hornbill in order for us to know how accurate the current listing of “Vulnerable” is. Looking at our neighbours (like South Africa) the hornbills are likely to have in fact moved into the “Endangered” state.

In 2020, we held the first strategic species conservation workshop for the Southern Ground Hornbill in Zimbabwe.

This workshop produced the first Species Conservation Strategy and Action Plan 2020 – 2021 for the Southern Ground Hornbill.

This included setting up eight focus area Whatsapp groups comprised of property owners, hunters and guides, researchers and interested citizens etc., to collect Southern Ground Hornbill sightings. For more information please Whatsapp +263775391486

S A V E T H E G R O U N D H O R N B I L L S

What can I do to help?

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2. Southern Ground Hornbills – general description

The southern ground hornbill (Bucorvus leadbeateri; formerly known as Bucorvus cafer) is one of two species of ground hornbill, both of which are found solely within Africa. (The other species of the genus is is the Abyssinian ground hornbill, Bucorvus abyssinicus.)

DISTRIBUTION & HABITAT

The southern ground hornbill is widely distributed, occurring from northern South Africa up to Kenya and Burundi, and across southern Africa through Namibia and Angola.

They are found in grassland and savannah areas with large trees for nesting and dense but short grass for foraging.

APPEARANCE & ADAPTATION

The southern ground hornbill is the largest species of hornbill.

The adult male has an extensive brilliant red face and throat wattles, while the adult female has purple-blue skin in the center of the red throat patch. Male hornbills can inflate their wattles during mating season to attract females.

Young birds can be identified by being smaller and having pale to yellow facial skin and a gular pouch by the first year, then flecked red by two years, orange by three years and only becoming fully red by four to six years.

Appearance by gender & age, repeated from above

BEHAVIOUR & HABITS

Hornbills live in a cooperative breeding group, with a breeding male and female. The group is usually made up of two to 11 individuals with males helping the breeding pair in defending the territory and rearing the chick. The dominant pair are the sole individuals to reproduce. (When you see a group it will consist of only one female, with several males, maybe several juveniles, and a chick.) Lone individuals are most often females.

The group roosts in trees or on rock faces, descending to the ground just before dawn and forage for about 70% of the day. They often take a break at midday to play, preen and pass around food to one another. The group cooperates in hunting difficult prey such as snakes and calls other members to good sources of food. Despite their size they can fly efficiently and are capable of carrying large food masses in the bill when in flight but typically they only fly to escape predators, or to perch in trees for night roosting.

These groups occupy and defend large territories (sometimes up to 100 square kilometers) against neighbouring groups and often chase each other in aerial pursuits.

CALLS

Southern ground hornbill groups are very vocal and have five different calls:

A sharp, fast grunt that is usually used when the birds are playing, fighting or when in distress;
A begging call that is usually used by juvenile birds when they beg for food. A begging call that is used by females during courtship feeding;
An alarm call that is used to alert the group when there’s a predator present;
A four note deep-bass booming call, “oooh..oooh..ooh-oh”, which can be heard at distances of up to 3 kilometers and is used as a long-range contact and territorial call to allow each group to maintain its territories. (This is sometimes mistaken for the roaring of lions.)

Some cultures in Africa believe the birds are keepers of time and interpret the bird’s characteristic call signals a change in season.

CULTURAL SIGNIFICANCE

The southern ground hornbill’s loud voice and large size have made it a focal point in many traditional African cultures where it is generally revered but it is also feared.

For some the ground hornbill is associated with death and unluckiness and as a sign, or bringer, of death, destruction, loss, and deprivation. This has led to a range of reactions to the southern ground hornbill, from avoidance to killing. For the Ndebele people, killing them is considered taboo and will bring death upon the killer. Furthermore, the Ndebele believe an elderly person will die if a southern ground hornbill comes near the home.

The ground hornbill has traditional associations with rain, drought, lightning and general weather forecasts. It is believed by the Ndebele, for example, that its early morning calls are a sign of rain. This association has led the southern ground hornbill to be attributed with the ability to provide protection from weather-related problems. It is believed that if the proper traditional ritual is used, the bird can protect against lightning and drought.

In Southern Africa, the bird can be called on through traditional rituals to improve or change a human’s ability to alter reality, create illusions, and expand awareness and ability to find food, creatures and even enemies. Furthermore, some believe that the ground hornbill can be used to alter the perceptions of oneself and it has been used in rituals to provide authority for leaders in certain cultures.

DIET

Ground hornbills are omnivorous and their diet sometimes includes fruits and seeds, but they are more likely to eat insects, toads, lizards, snakes, tortoises, hares, rats, squirrels, and even small monkeys.

Hornbill & scrub hare. Photo by Derek Whalley

They forage on the ground and the group moves slowly through the bush, in sight of each other, turning over smaller stones, sticks and branches looking for food. At times, a prey item may dash into cover and other family members will then be called to assist in extracting the prey. They often find prey by digging, especially in dung heaps. During seasons where Red-billed Queleas (Quelea quelea) are abundant, southern ground hornbills may be found plucking nestlings direct from their nest. They are kleptoparasitic and will steal prey from other birds of prey, where possible. Because of their foraging habits, other insectivorous species such a bee-eaters, goshawks and drongos may be seen alongside southern ground hornbills looking for insects in the grass. Similarly, southern ground hornbills may feed alongside chacma baboons where a larger area is covered and ‘disturbed’, while both hornbills and baboons go in search of food.

Southern ground hornbills rarely drink.

LIFE CYCLE

These birds are a long-lived species, having lifespans in the range of 50–60 years, and up to 70 in captivity. they do not reach sexual maturity until 4 to 6 years of age and begin breeding around 10 years old.

The southern ground hornbill is a monogamous cooperative breeder, with each breeding pair always assisted by at least two other birds who are either adult males or juveniles from previous breeding seasons. Only the dominant male and female copulate. The male helpers that assist the breeding pair in defending the territory, feeding and rearing chicks. Experiments in captivity have found that birds without six years experience as helpers at the nest are unable to breed successfully if they do become breeders. This suggests that unaided pairs cannot rear young and that the skill gained in helping as a juvenile is essential for rearing young as an adult.

The nest is usually a cavity high up in a tree. Occasionally they nest in cavities in rock faces or earthen banks. The nest is lined with dry leaves. The same site is used repeatedly over many breeding seasons.

One to three eggs are laid at the beginning of the wet season. The eggs are laid three to 14 days apart and incubated for about 40 days. During incubation the female is fed by the male and the helpers. They are the only hornbill species to not seal up the female inside the nest and, unlike other hornbill species, do not undergo an extensive moult while in the nest.

By the time the second egg hatches its older sibling will outcompete the latecomer for food, and consequently only one chick is raised past the first couple of weeks, the younger chick dying of starvation. Breeding success is therefore slow, with only one chick being added to a family group.

Young birds will leave their nest after about three months and will join the rest of the family group as they forage for food. They remain dependent on the parents and helpers for between one and two years depending on climatic conditions, longer than any other bird. This means that ground hornbills can normally breed successfully only every third year.

CONSERVATION STATUS & THREATS

This hornbill is an apex predator with very few natural predators though leopards and martial eagles prey on all ages. Genets and snakes prey on the chicks.

Southern ground hornbills are classed as VU (“vulnerable to extinction” on the IUCN Red List) globally. In South Africa, Lesotho, Namibia and Swaziland the species is listed as Endangered. This listing is mainly because of severe decline in the species’ range. In South Africa the species range has declined by approximately 50%. Also the species numbers have declined by 10% over the past 30 years. There is reason to believe that this is happening in Zimbabwe as well – hence the above appeal for sighting information. Ground hornbills are still widespread in areas less populated by humans, such as north-eastern Botswana and northern Zimbabwe, but they are still never common.

A decline in numbers is heavily tied to their slow reproductive rates.

But as is so often the case the main threat to ground hornbills comes from human activities. As they require vast amounts of space for their territories they are especially threatened by general habitat loss (in some countries they have lost 70 – 90% of their original range and are now only common in large, protected areas) and in particular by the loss of trees due to human expansion, extensive farming, bush encroachment, over grazing and climate change. A lack of large trees results in the birds being unable to find suitable roosting and nesting sites.

Flooding and severe weather due to climate change has wreaked further damage, as has widespread use of pesticides by farmers in hornbill habitat.

In some areas they are killed because, owing to the bird’s territorial behaviour, they sometimes cause significant damage to windows, mirrors, or anything reflective. To the birds, they see their reflection as an intruding bird and therefore attack and peck at it, often breaking the glass windows or mirrors in human habitations. This sometimes results in deliberate poisoning of the birds.

Poisoning also threatens hornbills. Occasionally, they will scavenge at carcasses and where the carcass has been laced with poison, eating the flesh will be fatal. Hornbills can also get lead poisoning when the carcass they are feeding on has been shot with a lead bullet.

CONSERVATION MEASURES

Various protection groups, including the Mabula Ground Hornbill Project, are working to reverse the decline by reintroducing the ‘doomed’ second chicks into areas where the species has become locally extinct. Where nests are located, the younger bird will be removed from the nest, hand-reared and introduced back into a wild population. Research has shown that intervention programs aimed at changing negative beliefs about hornbills are also effective, as is properly covering windows to prevent the birds from seeing their reflections and crashing into the glass. Great efforts have been made to mitigate threats, by undertaking an extensive education and awareness campaign in areas where the birds still occur, and providing artificial nests for wild groups.

For more information on the Mabula Ground-Hornbill Project, please contact Lucy Kemp at +27 (0)83 289 8610 or project@ground-hornbill.org.za, or visit their website at http://www.ground-hornbill.org.za/.

SOURCES

“Bucorvus leadbeateri (Southern ground-hornbill)”, Iziko, Museums of South Africa,

http://www.biodiversityexplorer.info/birds/bucorvidae/bucorvus_leadbeateri.htm

“Southern ground hornbill”, Wikipedia, https://en.wikipedia.org › wiki ›

“Southern Ground-Hornbill Bucovus leadbeateri”, eBird, https://ebird.org › species › soghor1

“Southern ground-hornbill, facts and photos”, National Geographic,

https://www.nationalgeographic.com › animals › birds

“Southern Ground-Hornbill”, SANBI, https://www.sanbi.org › Animal of the week

“Southern Ground Hornbill – Facts, Diet, Habitat & Pictures”, AnimaliaBio,

https://animalia.bio › southern-ground-hornbill

“Southern ground-hornbill (Bucorvus leadbeateri) Fact Sheet”, Libguides,

https://ielc.libguides.com › sdzg › southern_groundhorn…