Ground Hornbill Husbandry and Welfare

Ann Turner*, Alan Kemp*, Dee De Waal*, Nick Theron*, Ben Botlhole*, Gillian Theron*, Delecia Gunn** and Lara Jordan***.

 

 

 

 

 

 

 

 

 

 

 

Mabula Ground Hornbill Conservation and Research Project *

Mabula Game Reserve,

Private Bag X1644,

Bela Bela, 0480,

Limpopo Province,

South Africa.

Tel : 0027 (0)83.743.4270 and 0027 (0) 14.734.1788

E-mail : project@ground-hornbill.org.za

Website :  www.mabulagroundhornbillconservationproject.org.za

 

Loskop Dam Nature Reserve**                                                                                                                              Chester Zoo***

P/Bag X606, Groblersdal, 0470, South Africa                                                                                                          Caughall Road, Upton, Chester, CH2 1LH, England

 

 

 

 

Thunderbirds or Rain birds

The ground hornbill is also known as a ‘Thunder’ or ‘Rain’ bird and they were held in awe by many of the Xhosa-speaking Pondos of the Transkei area. People regarded them as being in league with the witch doctors that were said to use them to further their nefarious works. During times of crippling drought people believed it was perfectly feasible to harness the powers of this bird in order to bring rain. The unfortunate bird would be caught, a rock was tied to its neck and it was hurled into the water. Copious rains were guaranteed to follow this operation within a very short time (Nevill 1984).

 

Distribution

The Southern Ground Hornbill Bucorvus leadbeateri was formally distributed throughout Africa south of the Equator, including Rwanda; Burundi;

S Kenya; north to Eldoret and Turkwell R; SE DRC; Tanzania (accidental to Zanzibar); Angola; Zambia; Malawi; N Namibia; N and E Botswana; Zimbabwe; Mozambique; N and E South Africa in Transvaal; Natal; and E cape Provinces (Kemp 1995, Eskom Red Data book).

 

However is has disappeared from several parts of its former range, maybe as much as 70% in South Africa and Zimbabwe. The core concentrations in South Africa lie in the extensive conservation areas of the Kruger National Park (KNP) and adjacent private reserves (Tarboton, 1987 in Kemp 2000), the conservation and farming areas of northern and midland KwaZulu-Natal (Cyrus & Robson 1980; Knight 1990 in Kemp 2000), and the rural areas of the Eastern Cape (Vernon 1986). It occurred at low densities in Swaziland and a gap in the range is becoming apparent, separating the population in northern KwaZulu-Natal and southern KNP (ASABI; 708-709 in Kemp 2000).

 

Historical records indicate a much (at least 50%) wider distribution in Gauteng, North West, Limpopo and Mpumalanga Provinces, having been in the Magaliesberg near Hartebeesport and Pretoria and at the Limpopo-Marico confluence during 1842, at Loskop, Nylsvlei and Northam in the 1940’s, and Haenertsberg, Pilgrims Rest and Hanglip up to the 1970’s. It was recorded near Durban’s Umlaas River in KwaZulu-Natal in 1840. It decreased in the grasslands of the Eastern Cape between 1900-1970. The overall range has decreased less, and no major declines have been reported since the early 1980’s (Kemp 2000) although there are now concerns for northern KZN, Swaziland and southern Mpumalanga.

 

Biology

The Southern Ground Hornbill is the largest avian species known to be an obligate cooperative breeder, and one of only four African hornbills thought to exhibit this social organisation (Kemp 1995).  Like most large birds, the Southern Ground Hornbill is unevenly distributed at low densities, defends large territories (about 100 square kms) and has widely spaced breeding sites (Kemp 1987, Kemp et al. 1989, Knight 1990 in Msimanga 2004).

 

The critical aspect of Southern Ground Hornbill breeding biology is a naturally low productivity. They nest in natural holes in large trees or on cliffs, rarely on old stick nests. The birds breed during the austral summer, with egg laying in September to December, usually after the first good rains (Kemp & Kemp 1991 in Msimanga 2004), but often not every year. On average, attempts to breed are every 2.6 years, but the average overall fledging rate in KNP was only one chick per group every 9.3 years (Kemp, 1995 in Msimanga 2004).

 

In South Africa clutch size is one or two eggs, rarely three, incubated for about 42 days. Since incubation commences with the first egg, the chicks hatch at least 5 days apart. Only one chick is ever reared by adults even in a captive environment when food supply is not an issue (pers comms Delecia Gunn, 2005). Fledging occurs around 86 days, after hatching, during which the adult female will brood and feed her chick for the first month, with assistance from and later joining the other group members. It was takes six years for a young bird to reach adulthood and most probably do not start breeding even then.  It was estimated that the first successful breeding in females in the wild would be around 15-17 years (Morrison 2005), but in captivity they are breeding at 10 years old. It is estimated that they live on average about 45 years, but maybe for up to 60 years or more years in the wild.

 

Threats

The Southern Ground Hornbill feeds over a wide range of savannah, grassland and farming habitats. Its primary threat is loss of habitat. This affects both quality of foraging habitats and loss of suitable breeding sites through human exploitation of trees, with firewood being removed and perhaps reducing the number of available nest sites (Johnson et al. 1998 in BBC Wildlife May 1996). The hornbills need a tree with a cavity with an internal diameter of at least 40cm. The aptly named leadwood is the most frequently used and long-lasting tree site in South Africa, but also the softer-wooded fig, ebony, marula and, where it occurs, the mighty boabab. Conservation of these key tree species is as important as caring for the hornbills themselves.  Over-utilization of savannas, leading to loss of ground cover and/or encroachment of woody bushes, and afforestation of grasslands both lead to reduction in the quality and area of foraging habitat available to the hornbills.

 

Groups have also been eliminated by indirect poisoning during campaigns against livestock-predators and rabies-carriers, to which their systematic terrestrial foraging makes them prone. Secondary trapping and snaring is also a probable cause for the same reasons. Unfortunately they are persecuted in developed areas, where their aggressive territoriality leads to attacks on and shattering of their reflection in window panes often leading to the bird being destroyed (Kemp 2000).

 

Another reason for its decline are body parts used for traditional practices associated with rain-making, mainly during drought. It has emerged as the animal species of most conservation concern from traditional medicinal use in South Africa (Maner et al. 1997 in Kemp 2000). Electrocution on power lines and the trade in the exotic bird industries often to supply zoos, are also thought to have an impact (pers comms Anne Turner).

 

Southern Ground Hornbill are also limited by availability of food. Their slow-breeding rates, (groups fledging one chick every nine years on average in South Africa) their delayed maturity and low adult mortality, around two percent per annum, make them susceptible to persecution and slow to recover from its effects. Together, this causes them to be rendered Vulnerable at least (Kemp 2000).

 

Husbandry

Southern Ground Hornbills should not be pinioned, but kept fully winged in large enclosures.  The length and breadth of their secondaries allow them to fly even when pinioned.

 

Enclosure design

The enclosure should be large enough for the birds to fly into high branches. Their wingspan is 1.5 meters and they require sufficient distance for flying up and landing. A good sized enclosure is 15 meters by 13 meters by 6 meters high (See photos below). Wire should be chain link 2” by 2” The temporary boma designs (seen below) gives an idea for an absolute minimum requirement for temporary accommodation e.g. quarantine or rehabilitation, but must not be a permanent enclosure. This particular boma is Leopard proof, which is a necessity if the birds are at risk. The roof should be lined with soft netting so they do not hurt themselves if they fly up.

 

The enclosures should have natural substrate and grass, long grass is the most natural environment as they forage and dig in it. They choose to be in the sun generally, but in the warmer climates especially they will need some shade. They will often have a midday sleep in the heat of the day, on the ground, but roost high in trees at night around 2.5 to3.0 meters high. They tend to perch towards the ends of branches and will perch in a different place each night given the option.

 

It is probable that a ‘mist system’ will encourage them to breed. The South African summer rains start around October with the main rains coming in December and January, this would lead to a natural explosion in the food supply e.g. frogs and insects, followed by a general build up in other animal numbers. A small sand pit of fine sand may be used for sand bathing or sun bathing.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                                                                   Enclosure at Loskop Dam Nature Reserve.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                                                                                              Umgeni River Bird Park

 

 

 

 

 

 

 

 

 

 

 

 

Diet

Hornbills are carnivorous birds and can be fed on a variety of meats from day-old chicks, mice and rats of all ages, game meat, chicken, snake, game birds, boiled eggs grass hoppers and mealworms are reported to work well. However the fattier meats such as beef should be kept as a smaller proportion of their diets.

 

Social Behaviour

The best form of behaviour enrichment is to form a small social group. They are very social birds with a complicated co-operative structure and in the wild live in groups of up to 8 – 12 birds. These groups will only have one alpha female and one alpha male. All the rest of the group are usually made up of subordinate males who are helpers to the breeding pair, and of any immature offspring. The helpers collect food and nesting material in the breeding season, and take part in territorial defence.

 

The adults may well kill a juvenile female in captivity, which cannot fly away. This has been known to occur after only a few months and it is advisable to remove a young female from the group around 4-5 months. In wild groups these young females are generally ignored, although they sometimes lag behind the group once mature, and will periodically be chased away.  In hand-reared groups, this is how she persists, until she can feed herself at probably two and half years old, and she has no protection from predators during this time.

 

Aggression

Ground hornbills can become aggressive towards their keepers - a suggestion is a chute to push the food in from outside, so that it lands on a platform that can be cleaned (See Temporary Boma).

 

Enrichment

These birds are very intelligent so it is advisable to build enrichment ideas into their enclosures and food structure.

 

Enclosure Design

If the enclosure has short and long grass and bushy areas with some trees it will allow plenty of variation for shade and sun. They will often use the shade in the heat of the day. Good strong level branching is ideal for this species with bark which they will endeavour to break off. Branching that has a variety of thickness and heights is advantageous especially if you have young birds in your group. Branching with forks will enable them to use these areas to break large food items such as rats. They will jam the item into a corner and then will use their beaks to break the food up. They have also been seen using tools to break up food items.

 

Installing a mister into an enclosure will serve a number of uses. Softening the ground with water gives them the opportunity to dig up the ground afterwards. As mentioned before it may also be a useful tool to stimulate breeding. They have also been seen bathing and sometimes drinking from the misters. It may be useful in hotter climes to have it running on the nest boxes to help prevent the chicks suffering from dehydration.

 

Building a pond into the enclosure will encourage amphibians and insects to the enclosure forming natural entertainment. The birds also play in the pools. It will increase moisture to the enclosure, which in the drier climates is advantageous. An ultra-violet light can also be suspended in the enclosure and switched on at night to attract insects that can be found the next day.

 

Food enrichment

As with carnivorous mammals, it is a successful technique to hide food around the enclosure. Feeding three or four times a day is advisable to help occupy their time. Feeding whole carcasses when available is a great enrichment e.g. game birds or pheasants.

 

A pile of leaves or hay, into which you can put meal worms/crickets/frogs etc. keeps them naturally busy for hours. Also hiding live food in Rhino or Elephant dung and placing it in the enclosure is a natural foraging behaviour where they hunt dung beetles in the wild.

 

Alternatively putting mealworms in a 2 litre coke bottle will have them throwing the bottle around to retrieve the mealworms. Or similarly placing a heavy rock in the bottom of a bucket so they can not tip the bucket and putting in leaves and mealworms will keep them entertained.

 

Throwing a cardboard box into an enclosure will also keep the birds entertained as they enjoy breaking it up.

 

Pairing

Sub-speciation of the Southern Ground hornbill has not been defined at the moment; so it is unclear whether variation exists across the species’ range. This could have repercussions on breeding and pairing in captive populations, and confirmation of this issue is important for future recommendations. In the absence of this information it is deemed prudent to maintain at least Southern African and East African stocks separately.

 

Females may need to be 10 years old before reaching sexual maturity in captivity, and males about 7-8 years old. Putting a young pair together will help the bonding process.

 

Nest box design

Nest box designs are varied but can be equally successful. A couple of designs are shown below.

 

 

 

 

 

 

 

 

 

 

 

 

                                       Artificial nests used in the wild at Mabula                                             Nest Box used at Loskop Dam Nature Reserve

                                    Ground Hornbill Conservation and Research                                                                   for captive breeding

                                                               Project

 

The nests should be as high as possible with branches outside the nest allowing the male to feed the female on the nest or to feed chicks. In hot climates it may be necessary to have shading over the nest box to prevent chick dehydration and or a mister that can run over the nest box. Air circulation holes should be put at the back of the box, and drainage holes in the base. A nest camera in the box is invaluable to aid husbandry of rearing birds and also for research purposes.

 

Parent Rearing

If the female is interested in breeding she is likely to spend an increased amount of time in the nest box, banging the inside (a protein rich diet can be given to the female at this time). These hornbills do not mud up the entrance hole. This early breeding behaviour has been seen in females around the age of five well before maturity.  The wild the nest is lined with grass with leaves on top. The parents can be seen taking new leaves and a food item to the nest box throughout the breeding season; this is likely to enable the box to be kept clean. Therefore adding leaves to the enclosure enables the parents to maintain a clean nest box. It is thought that fresh leaves especially damp leaves will increase humidity in the nest. In the event of a particularly hot season it is advisable to put damp leaves in the enclosure for the parents to utilise. In captivity a mixture of wood chip and hay has also been used successfully.

 

In our wild and captive experience of parent rearing, these hornbills will never rear both chicks no matter how much food you give them and how many helpers they have. Therefore it is prudent to remove the second chick and hand rear.

 

The diet for the enclosure whilst rearing chicks has been successful with the following regime. Feed every two hours from day 1, chopping up the food, and skinning and removing egg yolk and bones. Add small crickets and mealworms if available. Increase the size of the food as the chick gets older. At around two months start introducing skin back into the diet. Eventually start adding bones, introducing foodstuff with soft bones and cartilage working up to whole day-old chicks.

 

Double Clutching

Double clutching for this species is in its infancy as far as knowing what effect it will have on the pair. Long lived intelligent birds such as Ground Hornbills need be given the opportunity to fail in the nest and ‘learn from their mistakes’. Dummying the eggs has been attempted with little success as the adults did not accept them as real eggs (the quality of the dummy eggs may affect this). Repeated taking of eggs may lead to an over protective response such as, destroying their own eggs. Furthermore they are very slow breeders bearing in mind that they attempt to breed on average every 2-2.5 years, which is the same length of time that it takes a chick to be able to fend for itself. The first signs from multiple clutching in the same year are that successive eggs and therefore chicks become increasingly smaller and weaker and in turn this will also have a long-term effect on the female. Clearly then it is important to plan your breeding strategy with careful consideration to the hornbills natural breeding cycle. Double clutching may improve productivity although repeated multiple clutching should not be performed.

 

Incubation

In most cases the hornbills will hatch both eggs and then will totally ignore one chick. Thus it is unlikely that incubating eggs will be necessary unless double clutching. There is some incubation experience available; the Zoological Society of San Diego incubated at 37.2ºC with relative humidity at 58.5%, hatching at 36.9ºC relative humidity at 66%. Abrey (1993) used an Anderson Brown moving carpet incubator, incubated eggs at a dry bulb temperature of 37.5ºC and a relative humidity of 52%. The eggs were automatically turned twelve times per day.

 

Other combined experience from South Africa of the Mabula Ground Hornbill Research and Conservation Project in conjunction with the National Zoological Gardens, Umgeni River Bird Park cc. and Montecasino Bird Gardens discovered that a 65% relative humidity for incubation proved a little too humid and caused hatching difficulties. The temperature used for incubation was 37.2ºC and relative humidity 45%-65% and weight loss was 14-15%.

 

Hand rearing

The decision to hand rear ground hornbill needs to be made in advance of breeding as to rear to fledging takes 85-90 days. After this time chicks are still fed by the hand-rearer and the parents would feed and teach chicks how to hunt for a further 2 to 2.5 years.

Chicks are placed in a bowl with non slip lining, (sheepskin or leaves) inside a brooder (between 30 and 35 degrees Celsius)

A feather duster is added to make the chick feel secure, control temperature and simulate an adult sitting on it.

No talking or human noises are allowed near the chicks. The only sounds they must be exposed to should be natural sounds. If you are not in an environment that can achieve this, a tape or CD of natural sound can be played softly.

 

The brooder temperature can be lowered every day as required by the chick. We find by about day 35 to 40 they no longer need a brooder but this will

depend on the climate.

 

The young hornbills habituate to humans easily and as  soon as the eye slits starts appearing, at about day 8, the hand rearer must wear clothing (a ghost) to disrupt their normal human shape when in sight of the chick and feeding must now be done with a puppet. If no puppet is available a black sock with a red patch sewed below the wrists can be used.

 

Bowl size must increase as the chicks grow, to give the chick adequate space but still keeping it secure as to avoid slipping and injuries to their legs.

From about day 12, weather permitting chicks can be taken outside for short periods of time. As the chick grows the amount of time spent outside can increase to the point where the chick will be outside for most of the day (approx. at day 40). They must be placed in a secure quiet area at all times as they are very prone to stress.

When the chicks leave the brooders, (± day 40) they are placed into a dustbin or artificial nest to simulate a natural nest environment.  These “nests” are lined with leaves to create a “natural” nesting environment. The chick will now be spending most of the day outside, and allowing vocal communication with other ground hornbills will aid the chick to relate to other Ground hornbills as they get older and not to humans so as to make the later integration into the group easier.

 

The chicks are placed outside in their “nests” in an enclosure from day 40 to fledging. This creates a safe environment for them to fledge into (approximately day 86). Their nests allow them to stand up and strengthen their legs as well as stretching their wings, preparing them for fledging.

From day 83, the chicks will be left outside in their nests in the enclosure during the day and night (weather permitting). Once the chick has fledged all human contact should be avoided to ensure that there is no association between humans and food.

 

A blood sample should be taken from the chicks just before fledging, care being taken to avoid the air sacks. This will allow for sexing of the chicks as well as any other tests that needs to be done. At this stage a transponder can also be placed under the skin on the left hand side of the neck.

 

The chicks will be left in the enclosure after fledging until they have learned to hop from branch to branch and can perch safely. As soon as their perching and hopping is sufficient they will be released into a group, but care must be taken that they can flee from adult persecution until their status in the hierarchy is established.

 

Hand rearing diet

Hand rearing diets vary between different organisations but some principles are listed below. Fluids are very important to chicks and video footage of adults feeding chicks fluids in the nest is available. However it is worth noting that hornbills do not drink water but get their fluids from their food, so as soon as the chick is viable without fluids often around day 12, then it may be wise to cease giving fluids. It is unwise to give food to chicks in the first 12 hours, as they will still be relying on their yolk sacs. Vitamins and minerals that should be added to diet including Calcium, Beefee powder (proteins), Probiotics and maybe B6.

 

The first 25 days are the most precarious as most birds are lost in this period. Impaction is one of the main causes of death so the focus below is a guide to the appropriate age to add difficult to digest substances. For the first couple of days the birds can be fed pinkies skinned and skulls crushed every couple of hours for approximately 7 feeds. Ringers lactate can be put on the food and 1 ml to be given orally after feeding, for each feed. Day 3 you can add a day-old rat pup and skinned fuzzies. By day 4 the birds may be fine on 5 feeds a day. From about day 8 chicken fillet can be used in the diet. By day 14 the birds may be fine on three feeds a day.

 

A large variety of different meats can be added to the diet depending on availability such as day old chick thighs, mealworms, termites, adult rat lung, liver and heart, even buffalo. A high quality soaked dry dog food can be added to the diet. At day 15 it’s possible to add adult mice (small) skinned ensuring the bones are not too long or sharp. Crickets without their hind legs have also been added at this time. By about day 18 you could introduce flesh and feather and by day 21 day old chick chopped up without fluff can be added to the diet.

 

Day 23 onwards you can introduce fuzzies with some skin on, introduce slowly with just part of the fur on. By day 36 you can add bone. By about day 45 the birds will be choosing to pick food for themselves which should be encouraged.

 

Growth rates can be very varied between individuals but 10-15% average daily weight gain for the first 30 days seems to work well. This can be reduced to a 3-5% average daily weight gain for the next 30 days. Below is a graph of growth rates of Southern Ground Hornbills which grew into healthy sub adults to the best of out knowledge.

 

IMPORTANT NOTES:

**Hornbill chicks will impact on fur, feathers, bones, insect exoskeletons, dirt, sand, and rocks.  Make all changes to roughage gradually!

**Weight gains should be maintained at 15-20% per day.

**Casting approximately Day 62

** Air sacs - develop subcutaneously on these birds within a couple of days and are not cause for alarm.

** Monitoring of faecal output is crucial throughout the entire rearing process!

         

 

References

 

BBC Wildlife. May 1996. Vulnerable Birds. Pg. 34.

 

Kemp, A.C*. The Ground Hornbills: Kemp. Bulletin ABC. 1 (1). Pp10-11.

 

Kemp, A.C. 1995. Bird families of the world The Hornbills. Oxford University press. Oxford. Pp302.

 

Kemp, A.C. 2000. Southern Ground Hornbill. In: Eskom Red Data Book of Birds South Africa, Lesotho and Swaziland. Birdlife South Africa. Johannesburg. Pp117-119.

 

Morrison, K., Daly, B., Burden, D., Engelbrecht, D., Jordan, M., Kemp, A., Kemp, M., Potgieter, C., Turner, A. and Friedmann, Y. 2005. Southern Ground Hornbills (Bucorvus leadbeater) PHVA Workshop Report. Conservation Breeding Specialist Group (SSC/IUCN)/CBSG South Africa; Endangered Wildlife Group.

 

Nevill, H. 1984. Some birds in Xhosa Folklore. Bokmakierie. 36 (2). Pp 29.

 

Vernon, C. J. 1986. The Ground Hornbill at the Southern extremity of its range. Ostrich 57:16-24.