Bucorvus abyssinicus

Geographic Range

Northern ground hornbills ( Bucorvus abyssinicus ) are found in the Ethiopian region across a wide area of north-central Africa, from southern Mauritania and Guinea in the west to Ethiopia, northwest Somalia, northeast Kenya, and northern Uganda in the east.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

Habitat

Bucorvus abyssinicus is found in savanna, sub-desert scrub, and rocky areas, preferring short vegetation which facilitates foraging. This species generally inhabits drier areas than southern ground hornbills ( Bucorvus leadbeateri ). Bucorvus abyssinicus tolerates disturbed areas but does require large trees for nesting sites.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• savanna or grassland savanna or grassland

Physical Description

The two species of ground hornbills, Bucorvus abyssinicus and Bucorvus leadbeateri differ from other hornbills in having an extra neck vertebra (giving them a total of 15), longer legs, thick upper eyelid lashes, and a larger body size. The longer legs adapt them well to their primarily terrestrial foraging method, while other hornbills are mainly arboreal. Northern ground hornbills are black, large-bodied birds average 4000 g in mass and 100 cm in length (Kemp, 2001). They have high, rounded, grooved casques (a bony elaboration of the upper mandible covered with a thin sheath of keratin) that is abruptly truncated distally, and a long, deep, curved beak, which they use to catch and subdue prey (Perrins, 2003). The primaries are white and are highly visible in flight. Northern and southern ground hornbills ( Bucorvus leadbeateri ) can be distinguished by differences in throat skin coloration and casque shape. Northern ground hornbill males have blue and red throat skin and a blue area around the eye, females have only bare blue skin both around the eye and throat. Southern ground hornbills ( Bucorvus leadbeateri ) have only bare red skin in both areas, and a smaller, shallower, non-truncated casque. Juveniles have brown feathers and less brilliantly colored throat patches. Northern ground hornbills have a yellowish patch at the base of the upper mandible.

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

• Sexual Dimorphism
• sexes colored or patterned differently
• ornamentation ornamentation

Reproduction

Northern ground hornbills are monogamous, with males tending to females and young during the incubation stage.

• Mating System
• monogamous monogamous

The breeding season depends on location, with West African populations breeding in June through August, Nigerian and Ugandan populations breeding in January, and Kenyan pairs breeding as late as November. The nest is constructed in a cavity of a large tree, with baobabs and palm stumps being preferred. However, they may also accept rock holes or man-made cavities such as bee-hive logs or baskets as nesting sites. Unlike other hornbills , in Bucorvus species females are not completely sealed into a nesting cavity. Instead, they are only partially sealed in by a mixture of mud and vegetation. They also does not undergo the typical synchronous flight feather molt typical of other incubating female hornbills. Males prepare the cavity by lining it with dry leaves, then the female enters and lays one or two eggs over approximately 5 days. Incubation begins with the first egg, so that one hatchling matures more quickly and grows faster than its nest mates. After 37 to 41 days of incubation, during which nest sanitation is not practiced and the male provides food items to the incubating female, the first egg will hatch, with the second hatching later. Newly hatched chicks weigh approximately 70 g. First-hatched chicks grow rapidly at the expense of the later-hatched sibling, which usually dies of starvation within 4 days, when the older sibling may weigh as much as 350 g. After 21 to 33 days the female will leave the nest to help the male in food acquisition and after 80 to 90 days the surviving hatchling fledges.

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

Northern ground hornbill males and females both invest heavily in their offspring. Males provide food for females who are walled into nest cavities with eggs during incubation. Both males and females protect and provide food for hatchlings. Fledged juveniles remain with their parents for up to 3 years, although sex can be determined visually at approximately one year of age. An average of one offspring is raised to independence every 9 years and investment per offspring is exceptionally high.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• post-independence association with parents
• extended period of juvenile learning

Lifespan/Longevity

Lifespan in captivity is 40 years.

Behavior

Northern ground hornbills are primarily terrestrial, though they will fly to capture prey or defend territory, and they roost in trees at night, possibly to avoid predation. They are often seen in pairs, though larger groups are encountered. Groups may form due to juveniles remaining in the parental home range for several years after they reach maturity. Juveniles of many hornbill ( Bucerotidae ) species, including both ground hornbill species ( Bucorvidae ), have been observed playing with vegetation and engaging in bill-wrestling. This may refine their motor skills for practical application in foraging and object manipulation as adults.

• Key Behaviors
• terricolous
• flies
• diurnal diurnal
• motile motile
• sedentary sedentary
• territorial territorial
• social social

Home Range

Groups of a few to up to 20 (rarely) individuals will defend a territory that may be as large as 260 m^2.

Communication and Perception

Males and females sing in booming duets (Kemp, 2001).

• Communication Channels
• visual visual
• acoustic acoustic

• Other Communication Modes
• duets duets

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

Food Habits

Northern ground hornbills are primarily carnivorous. They eat reptiles, including puff adders ( Bitis ), cobras ( Naja ), tortoises ( Testudinidae ), and lizards, and mammals such as hares ( Lepus ) and mongooses ( Herpestes ). Arthropods, mainly insects and arachnids, make up most of their animal diet. They sometimes takes carrion to supplement live prey. Northern ground hornbills follow ungulate herds and forest fires to feed on prey items fleeing these disturbances. Individuals walk up to 11 km per day, overtaking and consuming edible animals in their path. They also dig for arthropods and honeycomb, and rarely consume plant matter. The strong beak is used to grab prey and disarm it.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • insectivore insectivore
  • eats non-insect arthropods
  • scavenger scavenger

• Animal Foods
• mammals
• reptiles
• carrion carrion
• insects
• terrestrial non-insect arthropods

Predation

Predators of this species include large carnivores, such as leopards. Human predation for food is common in some places, such as northern Cameroon and Burkina Faso. Eggs and nestlings may be preyed on by smaller, terrestrial predators.

Ecosystem Roles

Bucorvus abyssinicus is a host for the mallophagan parasites Bucorvellus docophorus , Bucerophagus productus , and Bucerophagus africanus . It also hosts the nematode species Histiocephalus bucorvi and the cestodes Chapmania unilateralis , Idiogenes bucorvi , Ophryocotyloides pinguis , and Paruterina daouensis . A captive, wild-caught individual perished from Aeromonas hydrophila , a common fish pathogen that was previously not known to affect wild populations. This species has also been known to perish in captivity in North America from West Nile Virus.

Economic Importance for Humans: Positive

Bucorvus abyssinicus is not often sold or hunted commercially, although they are commonly held in zoos. The species has cultural value in some areas, where hunters may tie the severed head and neck to their own to facilitate stalking of ungulates. The call is often imitated and some villages have entire songs about the male and female duets.

• Positive Impacts
• pet trade pet trade
• body parts are source of valuable material
• ecotourism ecotourism

Economic Importance for Humans: Negative

In some areas northern ground hornbills are killed for breaking windows (by attacking their reflection) and for being cultural symbols of bad luck.

• Negative Impacts
• household pest

Conservation Status

Bucorvus abyssinicus is not currently threatened, but destruction of suitable nesting trees could impact the species negatively in the future. Disturbed grassland areas are actually preferred for hunting, and therefore it is unlikely that mild to moderate disturbance would have a negative impact on the population. However, where they are hunted for food, such as in northern Cameroon and Burkina Faso, they can be severely depleted or locally extirpated.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Brianne Krause (author), Michigan State University, Pamela Rasmussen (editor, instructor), Michigan State University.

References

Canaris, A., S. Gardner. 2003. Bibliography of helminth species described from African vertebrates 1800-1967. Pp. 1-101 in A guide to helminth species described from African vertebrates . Lincoln, Nebraska: University of Nebraska, Digital Commons. Accessed February 01, 2009 at http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1003&context=parasitologyfacpubs .

Clay, T. 1955. A New Genus of Ishnocera (Mallophaga). Proceedings of the Royal Entomological Society of London , B(24): 1-7. Accessed September 13, 2008 at http://www.phthiraptera.org/Publications/0211.pdf .

Elbel, R. 1967. Amblyceran Mallophaga (biting lice) found on the Bucerotidae (hornbills). Proceedings of the United States National Museum , 120: 1-75. Accessed February 01, 2009 at http://www.phthiraptera.org/Publications/1280.pdf .

Gretillat, S. 1967. [Helminths, parasitic to wild animals in Senegal. Histiocephalus bucorvi n.sp. (Hedruridae, Nematoda) parasite of the succenturiate ventricle of Bucorvus abyssinicus (Boddaert) (grand calao of Abyssinia)]. Annales de Parasitologie Humaine et Comparee (Paris) , 42(5): 533-542. Accessed February 01, 2009 at http://www.ncbi.nlm.nih.gov/pubmed/6083111 .

Kemp, . 2001. Family Bucerotidae (Hornbills). Pp. 437-487 and 488-489 in Handbook of the Birds of the World , Vol. 6 From Mousebirds to Hornbills, 2001 Edition. Barcelona: Lynx Edicions.

Komar, N. 2003. West Nile Virus: Epidemiology and ecology in North America. Advances in Virus Research , 61: 185-234. Accessed February 01, 2009 at http://www.westnile.state.pa.us/action/WNV_Komar_Adv_Vir_Res_61.pdf .

Ocholi, RA, R., J. Kalejaiye. 1990. Aeromonas hydrophila as cause of hemorrhagic septicemia in a ground-hornbill ( Bucorvus abyssinicus ). Avian Diseases , 34(2): 495-496.

Perrins, C. 2003. Firefly encyclopedia of birds . Toronto, Canada: Firefly Books.

Thiollay, J. 2006. Large bird declines with increasing human pressure in savanna woodlands (Burkina Faso). Biodiversity and Conservation , 15: 2085-2108. Accessed February 01, 2009 at http://www.springerlink.com/content/km1357601m762762/fulltext.pdf?page=1 .

Thiollay, J. 2001. Long-term changes of raptor populations in northern Cameroon. The Journal of Raptor Research , 35(3): 173-186. Accessed February 01, 2009 at http://elibrary.unm.edu/sora/jrr/v035n03/p00173-p00186.pdf .