Southern Yellow-Billed Hornbill(Tockus leucomelas)
It is a medium-sized bird, 48–60 centimetres in length, 132–242 grams in weight and is characterised by a long yellow and down-curved beak. The beak is huge in comparison to its body and can account for up 1/6th of the entire body length. Male beaks are on average 90 mm long while female beaks are an average of 74 mm. Males are generally bigger than females but there is overlap between the sexes. The size difference of the beak is a fairly reliable way of differentiating sex in wild hornbills.
The casque that characterises all hornbills is of a very modest size in the southern yellow-billed hornbill.
It is small, but it covers almost the entire length of the beak in males (less so in females), and may give the impression that they do not actually have a casque. As in all hornbills, the size of the beak actually intrudes on the frontal vision of the bird and the first two neck vertebrae are fused together. Also, like most other hornbills, they possess a long tail, long eyelashes, stubby legs and stubby toes. The front three toes are fused together near the base. They have white belly, grey neck, and black back plumage with abundant white spots and stripes. The neck has gray spots and the chest is lightly striated with black. Southern yellow-billed hornbills have no plumage pigmentation save for melanin, which can only produce shades of black and white. The eyes are usually yellow, though brown has also been seen. The skin around the eyes and in the malar stripe is pinkish. The related eastern yellow-billed hornbill from north-eastern Africa has blackish skin around the eyes.
Habitat
These birds are near endemic to the dry savannahs of southern Africa, where they can be found across all longitudes, from Angola and Namibia in the west to Mozambique and KwaZulu-Natal in the east, including Botswana, Zimbabwe and northern South Africa. The southern yellow-billed hornbill lives mostly in the dry, open savannas, but they are also very partial to woodlands when they can find them. When in woodlands, they seem to prefer acacia and broadleaved woodlands. The highest reported concentration of southern yellow-billed hornbill is in open mopane scrub.
Diet
Southern yellow-billed hornbill eats mostly arthropods, particularly termites, beetles, larvae (beetles and termites), grasshoppers and caterpillars. It has also been seen eating centipedes and scorpions. They will occasionally eat small mammals when they can. To complete the diet, they will regularly eat berries, fruits, nuts and eggs from other species. Southern yellow-billed hornbill use their beaks as a pair of forceps. They will grasp their food between the tips and then toss it back in their throat where the short, stubby tongue will assist in swallowing the food. The inner cutting edges of the beak are serrated to facilitate the crushing and fragmentation of food. Most of the food is picked from the ground or from low vegetation. Their diet has some overlap with that of the southern ground hornbill.
Breeding
Breeding season starts when the first autumn rain falls. The breeding season goes from September to march with the egg-laying peak between October and December. Eggs are laid during the wet season so different areas will have different peaks according to the local rainy season. For example, the peak generally occurs from November to February in the eastern regions and from December to March in the northwest regions of the southern yellow-billed hornbill's range. These peaks coincide with the peak rainfall of the year. Young birds become sexually mature when they are one year old. However, before the actual breeding is done, there is the courtship feeding of females, mutual preening, copulation and prospecting of nests sites that must be done. Once the male southern yellow-billed hornbill has mated, it will stay with his mate and establish a territory that it will defend. The nests are placed in natural cavities in trees, cliffs or earth banks between 1 and 12 meters from the ground. The male then proceeds to bring bark, leaves and grass which will be put on the bottom of the nest. During this time, the female will seal herself inside the nest by blocking the entry with a wall made from her droppings and food remains. The male will help by bringing mud for her to work with. The only opening left is a vertical slit from the top to the bottom. The male passes the food through the slit with his beak. The female and chick droppings are forcibly expelled through the slit as well. The vertical slit provides good air circulation through convection and when coupled with the wooden walls, it provides a good insulation.
Nests usually contain 2-6 eggs and take about 24 days to hatch. The eggs are white, oval and have finely pitted shells. The chicks are born naked and with pink skin. They and the female are fed by the male who brings back food and drops it through the slit. Most nests will also have a long escape tunnel in case a predator breaks in the nest to eat them.Taking advantage of the fact that she is imprisoned; the female will shed all of her flight and tail feathers simultaneously and regrow them during the time she stays with the chicks. Once the chicks are half-grown, the female will break out of the nest in order to help the male. The chicks will rebuild the wall themselves and continue to be fed through the slits by the parents. Once the chicks are fully grown, they will break out of the nest and start flying.
Population
According to the IUCN Red List, they are classed as Least Concern(LC). The global population size has not been quantified, but the species is reported to be widespread and common. The population is suspected to be in decline owing to destruction of large trees which provide nesting sites.
Threats
Their main threat is that large trees that they use for nesting sites are being destroyed.
Conservation
There are currently no conservation actions for this species.