Bucorvus leadbeateri

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.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

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.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes colored or patterned differently
• male more colorful

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.

• Mating System
• monogamous monogamous
• cooperative breeder cooperative breeder

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 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 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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

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.

• Parental Investment
• altricial altricial
• male parental care male parental care
• female 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.

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.

• Key Behaviors
• terricolous
• diurnal diurnal
• motile motile
• sedentary sedentary
• territorial territorial
• social social
• dominance hierarchies dominance hierarchies

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.

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.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Other Communication Modes
• duets duets

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

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.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • insectivore insectivore
  • scavenger scavenger

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

• Foraging Behavior
• stores or caches food stores or caches food

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.

• 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.

• Positive Impacts
• ecotourism ecotourism

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.

Additional Links

Encyclopedia of Life

Contributors

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

References

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