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Bucorvus leadbeaterisouthern ground hornbill(Also: southern ground-hornbill)

By Vincent Gentilcore and Amanda Sorenson

Geographic Range

Southern ground hornbills (Bucorvus leadbeateri) are restricted to sub-Saharan Africa. These birds are non-migratory, remaining in their particular habitat throughout the year. They range from southern Kenya, just south of tropical Africa in the north, to Botswana in the south, just north of South Africa. Their range extendeds east to west within this region because topography and habitat are similiar from east to west. While their range typically does not extend into South Africa, they have been spotted in Kruger National Park in northern South Africa. They also have been reported in Tarangire National Park in Tanzania. ("The IUCN Red List of Threatened Species", 2010; Kemp, 1995)

Habitat

Hornbills are ground dwelling birds and rarely aboreal. Bucorvus leadbeateri mainly lives in dry climates in the savannas and grasslands of central Africa. They also have been reported in forests of eastern Africa, extending to nearly 3000 m above sea level. These habitats experience a wet and dry season though, with hornbills varying their feeding behaviors and activity levels based on seasonal availability of resources. The distribution of hornbills does not extend north beyond southern Kenya, because there the biome type changes and less suitable tropical conditions occur. ("The IUCN Red List of Threatened Species", 2010)

  • Range elevation
    3000 (high) m
    9842.52 (high) ft

Physical Description

Southern ground hornbills are the largest birds in the hornbill family (Family Bucerotidae), reaching up to 100 cm tall. Southern ground hornbills resemble closely related northern ground hornbills, but have distinct markings. The plumage of these birds is entirely black with distinct white primary feathers. In southern ground hornbills, sexual dimorphism is evident. Males have continuous red coloring on their face and neck, while females have blue coloration on their throat. Northern ground hornbills differ from southern ground hornbills in that their face and neck are almost completely blue in color. Juvenile southern ground hornbills have the same feather coloration as adults, with black plumage and white primaries, however the coloring on the throat is less distinct than in adults. Both southern and northern ground hornbills differ from other hornbills in that they are well-adapted for moving and living on the ground, rather than an arboreal lifestyle. This is shown by their large beaks, head, and body, as well as their stocky legs comparative to their overall size. Another distinguishing characteristic possessed by southern ground hornbills is their inflatable throat sac. They have long eyelashes to aid in shading their eyes. There is no geographical or seasonal variation within this species, nor are there different morphs. (Alderfer, 2009; Branch, et al., 2007; Meiri and Yom-Tov, 2004; "Hornbills", 2006)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • male more colorful
  • Range mass
    2.2 to 4.2 kg
    4.85 to 9.25 lb
  • Average length
    100 cm
    39.37 in
  • Range wingspan
    1.2 to 1.8 m
    3.94 to 5.91 ft

Reproduction

Mating occurs seasonally in early summer for southern ground hornbills, but not every year. Southern ground hornbills are monogamous. Attraction is based on size of the bird. Thus, there will be just one mating pair, because only the largest female and male reproduces (alpha mates). These individuals produce the offspring; the rest of the flock serves as helper birds. Male hornbills are not known to fight over females and lack any elaborate courtship displays, but males do produce mating calls when courting females. ("Southern Ground Hornbill", 2010; "The IUCN Red List of Threatened Species", 2010)

Southern ground hornbills have a copulation and nesting period that lasts from September to December. During this time, the female spends much of her time in a large cavity in or around trees and cliffs. This cavity is usually made of leaves nestled within the tree or cliff. Eggs usually hatch 37 to 43 days after copulation. Once hatched they have 86 days until fledging. There is also a three to seven day rest period between laying the eggs, so the first chick is three to seven days older than the second. ("Southern Ground Hornbill", 2010; "The IUCN Red List of Threatened Species", 2010; Krause and Rasmussen, 2009; "Hornbills", 2006; Turner, et al., 2010)

Southern ground hornbills live in social groups of about two to eight individuals, with cooperative breeding and care for the offspring. This beneficial because just two eggs are produced and usually only one will survive to the fledging stage. Often the second chick dies from malnutrition. In some areas, such as South Africa, nests have been reported to produce only one independent fledging every nine years. In the Okavango Delta of Botswana, these birds tend to breed more frequently. ("Southern Ground Hornbill", 2010; "The IUCN Red List of Threatened Species", 2010; Krause and Rasmussen, 2009; "Hornbills", 2006; Turner, et al., 2010)

Southern ground hornbills reach sexual maturity at about three years of age. At this time, the facial skin of males becomes entirely red and that of females becomes violet blue below the bill, indicating sexual maturity. ("Southern Ground Hornbill", 2010; "The IUCN Red List of Threatened Species", 2010; Krause and Rasmussen, 2009; "Hornbills", 2006; Turner, et al., 2010)

  • Breeding interval
    Southern ground hornbills breed seasonally but not every year.
  • Breeding season
    Nesting and copulation happens between September and December.
  • Range eggs per season
    1 to 3
  • Range time to hatching
    37 to 43 days
  • Average fledging age
    86 days
  • Range time to independence
    9 (high) years
  • Average age at sexual or reproductive maturity (female)
    3 years
  • Average age at sexual or reproductive maturity (male)
    3 years

There is only one mating pair in each southern ground hornbill flock. The fertilized female enters the nesting area, which is prepared by the male. The nesting area is usually surrounded by leaves and protected in a tree or rock cavity. The male protects the female while she is nesting, watching for small predators that may steal their eggs. Southern hornbills show cooperative breeding. The male and other hornbills in the flock provide food for the incubating female. Once the chicks hatch, the offspring receive care from both the parents and the rest of the birds in the flock. "Helper" males usually only provide food. Approximately four weeks after hatching her first chick, the female leaves the nest. After fledging (~86 days), the chick is relatively self-sufficient, however its parents will continue to guide and provide protection for the offspring until maturity and complete independence. Investment in offspring is quite high, as some hornbills main remain dependent on their parents for as long as nine years. ("Southern Ground Hornbill", 2010; "Hornbills", 2006)

  • Parental Investment
  • altricial
  • male parental care
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • male
      • female
    • protecting
      • male
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
  • pre-independence
    • provisioning
      • male
      • female
  • post-independence association with parents
  • inherits maternal/paternal territory

Lifespan/Longevity

Little is known about the lifespan of southern ground hornbills in the wild. However, in captivity, they have been reported to live approximately 70 years. (Dunning, 2008)

  • Range lifespan
    Status: captivity
    70 (high) years

Behavior

Southern ground hornbills often live in small groups of 2 to 11, often related, birds. Within each of these small groups, a dominant (alpha) pair of male and female birds are usually chosen based on size and age of the birds. There is also one dominant breeding male and female within each group. Other hornbills within the group typically act as "workers". These birds locate much of the food for the group. The flock may also include juvenile hornbills that have not yet left their home territory. (Branch, et al., 2007; Turner, et al., 2010; Vernon, 1997)

  • Average territory size
    100 km^2

Home Range

Southern ground hornbills are non-migratory birds. They remain in their defined territory throughout the year. "Worker" birds in the flock help to defend their territory. Hornbills use vocal means to define their territory, setting up chorus calls that can be heard by other birds up to 2 km away. The home range of southern ground hornbills is very large, ranging from 50 to 100 or more km. This is similar in size to that of closely related northern ground hornbills (Bucorvus abyssinicus). Most southern ground hornbill territories are located in open spaces such as savannas or woodland habitats. (Turner, et al., 2010; Vernon, 1997)

Communication and Perception

Southern ground hornbills do not vocalize often. Vocalization typically occurs during the breeding season and help in mate selection. During this time, they make sounds that are often described as booming. They create this sound by enlarging their air sacs (filling them with air) and then releasing this air. They also make a very low booming sound when interacting with family members, which may include eight or more hornbills living together as a single family unit. There are also interactions that occur between juvenile hornbills. These birds enjoy more tactile forms of interaction, including playful fighting (in which they use their bills to attack each other) and chasing one another. Southern ground hornbills rely heavily on vision and have long eyelashes to help keep dirt and sunlight out of their eyes. They have binocular vision, allowing them to see their bills and to manipulate objects that they are holding. (Alderfer, 2009; Diamond and Bond, 2003)

  • Other Communication Modes
  • duets

Food Habits

Southern ground hornbills are generally carnivorous birds, eating a range of terrestrial animals, including amphibians, small mammals, and some reptiles. When prey availability is severely limited, they also have been known to eat dead animals. However, the main source of food for hornbills is insects. These birds often walk around scavenging for food, often in groups. They use their large beaks to attack slightly larger prey. Their large mouths and beaks allow them to eat their prey whole, as they do not have any teeth for chewing. Southern ground hornbills also sometimes will store their food and line the food up and eat the prey they collected, one by one. (Alderfer, 2009; Kindersley, 2011; Krause and Rasmussen, 2009)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles
  • insects

Predation

Because southern ground hornbills live on the ground, they are more vulnerable to attacks from large predators such as leopards and crocodiles. Juvenile southern ground hornbills are the most susceptible to attacks. Southern ground hornbills do not have many anti-predator adaptions. However, they do produce loud calls by filling and releasing air from their air sacs, which can scare off potential predators. They can also give alarm calls to warn other hornbills in the area of potential threats.

Ecosystem Roles

Northern ground hornbills (Bucorvus abyssinicus), closely related to southern ground hornbills, are affected by many parasites, including chewing or bitting lice (Bucorvellus docophorus and Bucerophagus productus). They also are parasitized by the nematode Histiocephalus bucorvi and some tapeworms, including Chapmania unilateralis, Idiogenes bucorvi and Paruterina daouensis. It is likely that some of these parasites similarly affect southern ground hornbills and other members of this family. (Krause and Rasmussen, 2009)

  • Ecosystem Impact
  • creates habitat

Economic Importance for Humans: Positive

Southern ground hornbills are common in zoos and wildlife sanctuaries in many parts of the world. ("Hornbills", 2006)

Economic Importance for Humans: Negative

There are no known adverse effects of Bucorvus leadbearti on humans.

Conservation Status

These hornbills are said to be widespread and fairly common, but declining. In 1992, the population was estimated at 1,400 mature individuals in northern South Africa. This suggests a 50% decline in population. According to the International Union for Conservation of Nature and Natural Resources (IUCN) Red List, Bucorvus leadbeateri is given the conservation status of "Vulnerable". The habitat for this species is being encroached upon by humans and many hornbills are killed by humans when they enter their properties. This status may also be given to southern ground hornbills because they have a relatively restricted distribution, only found in a particular areas of Africa, which may restrict their chances for survival. ("The IUCN Red List of Threatened Species", 2010)

Contributors

Vincent Gentilcore (author), Radford University, Amanda Sorenson (author), Radford University, Christine Small (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cooperative breeder

helpers provide assistance in raising young that are not their own

diurnal
  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

scavenger

an animal that mainly eats dead animals

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

References

Natural Encounters Inc. 2006. "Hornbills" (On-line). Accessed November 06, 2011 at http://www.naturalencounters.com/hornbillis.html.

2010. "Southern Ground Hornbill" (On-line). Accessed November 15, 2011 at http://www.lintonzoo.com/factsheets/Animals/GroundHornbill.html.

2010. "The IUCN Red List of Threatened Species" (On-line). Bucorvus cafer. Accessed October 11, 2011 at http://www.iucnredlist.org/apps/redlist/details/142031/0.

Alderfer, J. 2009. National Geographic: Complete Birds of the World. Monterey, CA: National Geographic.

Branch, , Stuart, Tarboton. 2007. Southern Africa. North hampton, Massechusetts: Interlink Books.

Butchart, D. 2009. Wildlife of South Africa: A Photographic Guide. Cape Town: Struik Publishers.

Coetzee, H. 2010. Observations of southern ground-hornbill Bucorvus leadbeateri grooming common warthog Phacochoerus africanus. African Journal of Ecology, 48/4: 1131-1133.

Diamond, J., A. Bond. 2003. A Comparative Analysis of Social Play in Birds. Behaviour, 140: 1091.

Dunning, J. 2008. CRC Handbook of Avain Body Masses. Boca Raton: CRC Press.

Graham, M., H. Coetzee. 2004. Visual fields in hornbills: Precision-grasping and sunshades. The International Journal of Avian Science, 146/1: 18-26.

Hinde, G. 2007. The Very Best of African Wildlife. Cape Town: Struik Publishers.

Hulley, P., C. Adrian. 2007. The status of the Southern Ground-Hornbill in the Grahamstown region, Eastern Cape, South Africa. Ostrich: The Journal of African Ornithology, 78/1: 89-92.

James, D., R. Kannan. 2009. Nesting habitat of the great hornbill (Buceros bicornis) in the Anaimalai Hills of Southern India. The Wilson Journal of Ornithology, 121/3: 485-492.

Kalina, J. 1989. Nest intruders, nest defence and foraging behaviour in the Black-and-white Casqued Hornbill Bycanistes subcylindricus. International Journal of Avian Science, 131/4: 567-571.

Kemp, A. 1995. The Hornbills. Oxford: Oxford University Press.

Kindersley, D. 2011. South Africa (Eyewitness Travel Guide). UK: DK Publishing.

Krause, B., P. Rasmussen. 2009. "Bucorvus abyssinicus" (On-line). Accessed October 26, 2011 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Bucorvus_abyssinicus.html.

Meiri, S., Y. Yom-Tov. 2004. Ontogeny of large birds: Migrants do it faster. The Condor, 106/3: 543.

Poulsen, H. 1970. Nesting behaviour of the black-casqued hornbill Ceratogymna atrata (Temm.) and the great hornbill Buceros bicornis L. Ornis Scandinavica, 1: 11/15.

Sinclair, I. 2009. Pocket Guide: Birds of Southern Africa. Cape Town: Struik Publishers.

Turner, A., A. Kemp, D. De Waal, N. Theron, B. Botlehole. 2010. "Captive Breeding" (On-line). Mabula Ground Hornbill conservation project. Accessed November 14, 2011 at http://www.mabulagroundhornbillconservationproject.org.za/index_files/Page3121.html.

Vernon, C. 1997. Ground Hornbill. The Atlas of Southern African Birds, 1: 708.

Witmer, M. 1993. Cooperative breeding by rufous hornbills on Mindanao Island, Philippines. The Auk, 110: 933-936.

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