The hornbill and the pitcher: a southern ground hornbill (Bucorvus leadbeateri) learns to solve the Aesop’s Fable task

The southern ground hornbill, Bucorvus leadbeateri, is on the IUCN Red List of Threatened Species as a ‘Vulnerable’ species with a decreasing population. Despite a myriad of threats, including loss of nesting sites, accidental poisoning and persecution, there has been no detailed study of the southern ground hornbill in Zimbabwe.We collected data on nest sites and usage for 42 nests over three breeding seasons in the communal areas surrounding the Matobo National Park. For the active nests in the breeding seasons of 2008/9 and 2009/10 the mean nearest neighbour distances were 4.41 km and 3.53 km, respectively. Most nests were found in granite crevices (67%) while the remainder were found in five different tree species. Most nests (90%) were in areas of subsistence crop farming, the remainder (10%) were found in forests and open savannas. The high breeding density of the southern ground hornbill in the communal areas surrounding the Matobo National Park in Zimbabwe could be attributed in part to traditiona...

Introduction: The conservation status of the Southern Ground Hornbill (Bucorvus leadbeateri) is vulnerable on the IUCN Red List. The Mabula Ground Hornbill Conservation Project (2011) and Southern Ground Hornbill conservation in general aim to increase the number of hornbills through five main techniques: (1) supplemental feeding, (2) double clutching, (3) alternation of chicks, (4) group augmentation and (5) chick fostering. Numbers are threatened directly by habitat loss, hunting and international trade, and indirectly by group size (through the Allee effect) and communal breeding. Furthermore, the species has a highly K-selected life-history pattern. Captive breeding of this bird can potentially increase the population size twofold because both eggs laid are guaranteed a chance of survival, whereas in the wild only one egg is likely to survive. Time-activity budgets in birds can be used to illustrate reproductive effort. Time-activity budgets are known for Southern Ground Hornbills from wild birds in the Kruger National Park and from one captive pair (Johnson B 2004, personal communication). We compared the time-activity budgets of captive Southern Ground Hornbills in the Johannesburg Zoo with randomly expected behaviour of the same birds and previously studied birds.

The Southern Ground Hornbill (SGH – Bucorvus leadbeateri) is one of the largest hornbill species worldwide, known for its complex social structures and breeding behaviours. This bird has been of great interest due to its declining population and disappearance from historic ranges in southern Africa. Despite being the focus of numerous conservation efforts, with research forming an integral part of these initiatives, there is still a substantial lack of knowledge regarding the molecular biology aspects of this bird species. In this study, whole genome sequencing of the SGH was achieved using Illumina short-read (NovaSeq 6000) and Pacific Biosciences long-read technologies. A hybrid de novo genome assembly followed by reference-based refinement produced a 1.16 Gb high-quality draft genome assembly of the SGH comprised of 1,672 contigs (N50 value of 40.45 Mb). The availability of this genome will aid in improving our current understanding of this bird at a genomic level and provide a pivotal foundation for comparative genomic analysis with other hornbill species.

Introduction: The conservation status of the Southern Ground Hornbill (Bucorvus leadbeateri) is vulnerable on the IUCN Red List. The Mabula Ground Hornbill Conservation Project (2011) and Southern Ground Hornbill conservation in general aim to increase the number of hornbills through five main techniques: (1) supplemental feeding, (2) double clutching, (3) alternation of chicks, (4) group augmentation and (5) chick fostering. Numbers are threatened directly by habitat loss, hunting and international trade, and indirectly by group size (through the Allee effect) and communal breeding. Furthermore, the species has a highly K-selected life-history pattern. Captive breeding of this bird can potentially increase the population size twofold because both eggs laid are guaranteed a chance of survival, whereas in the wild only one egg is likely to survive. Time-activity budgets in birds can be used to illustrate reproductive effort. Time-activity budgets are known for Southern Ground Hornbills from wild birds in the Kruger National Park and from one captive pair (Johnson B 2004, personal communication). We compared the time-activity budgets of captive Southern Ground Hornbills in the Johannesburg Zoo with randomly expected behaviour of the same birds and previously studied birds.

A 20-year-old southern ground hornbill (Bucorvus leadbeateri) developed hyperpigmented macules on its gular pouch, resembling the lesions typically seen in humans with pityriasis versicolor. Cytologic examination revealed over 100 budding yeasts per oil immersion field. Fungal culture showed rare growth of smooth, cream-colored yeast colonies, identified by PCR as Malassezia slooffiae. Histopathological analysis showed lymphocytic perivascular dermatitis. Periodic acid-Schiff staining revealed rare forms of yeasts between the layers of the stratum corneum. This clinical report provides further insights into the role of Malassezia spp. in the avian skin microbiome. To the authors' knowledge, this is the first report of Malassezia sp. as an agent of pityriasis versicolor in birds.

The southern ground hornbill (Bucorvus leadbeateri) has been classified as globally vulnerable and, in South Africa, regionally endangered, with a negative population trend. Factors contributing to the population decline in South Africa are poisoning, electrocution, and illegal capture for trade, coupled with slow reproductive rates and extensive habitat requirements. Lead toxicosis is a previously undescribed threat for the population. An adult southern ground hornbill presented with acute lead toxicosis due to lead particles in the gizzard, which required intensive treatment. Two other hornbills were likely exposed. The source of the lead in these cases was likely a carcass of a porcupine that was killed with lead shot. This report highlights the importance of the use of lead-free ammunition within the habitat of the southern ground hornbill in South Africa.

Enrichment is essential for the welfare of many zoo-housed animals, yet the value of enrichment is not well understood for all taxa. As an intelligent, long-lived species, the southern ground hornbill (Bucorvus leadbeateri) is a good model for enrichment research. A pair of southern ground hornbills, housed at Beale Wildlife Park and Gardens, were observed during study periods in 2014, 2018, and 2019. Three types of enrichment were provided for the birds; these enrichment types were developed based on information on the habits of the species as found in natural history papers. The enrichment types consisted of a pile of twigs, small animal carcasses, and plastic mirrors. Overall, the carcass feeds and the mirrors resulted in the greatest changes in behavior, with hornbills engaging in long periods of food manipulation with carcasses. For the mirror condition, hornbills spent time stalking around and pecking at mirrors, similar to the ‘window smashing’ behavior seen in wild hornbills. Overall, the research suggests that not only can enrichment modify the behavior of southern ground hornbills, but non-nutritional enrichment may be equally valuable to the animals. Natural history papers may have some value in inspiring novel enrichment items for zoo-housed animals.

The combination of midazolam, medetomidine and azaperone (MMA) was compared with the combination of butorphanol, azaperone and medetomidine (BAM) for the sedation of southern ground hornbills when administered orally in a bait. The BAM combination (30 mg butorphanol, 12 mg azaperone and 12 mg medetomidine per ml of solution) at a dose of 0.14 ml/kg was the only combination that did not result in re‐sedation after reversal. However, induction of sedation was long, and sedation was only deep enough for capture, handling, and minor non‐invasive procedures. The MMA combination and higher doses of the BAM combination resulted in quicker inductions although individuals showed mild to severe signs of re‐sedation, starting at 4 hours after reversal and continuing for as long as 17 hours after reversal. Care should therefore be taken when administering these combinations orally to southern ground hornbills as it appears that absorption, metabolism and excretion are unpredictable in this species.

The southern ground-hornbill (Bucorvus leadbeateri; hereafter SGH) is endangered in South Africa, Namibia, and Swaziland. Through a conservation program established in South Africa by the Mabula Ground Hornbill Project, wild populations are being re-established by the reintroduction of captive-reared birds. The SGH is susceptible to infection with avian avulavirus 1, which causes Newcastle disease (ND). Four different vaccines to protect against ND were administered through various vaccination schedules and evaluated by serologic monitoring to assess the efficiency and safety of various combinations of vaccines (live versus inactivated/killed), vaccine strains (Ulster strain, live; Avivac Cellimune, live; VG/GA strain, live; and Avivac Struvac, killed), and administration routes (intraocular versus subcutaneous versus intramuscular injection versus oral). We vaccinated 75 individuals and evaluated antibody titers in 53 individuals (24 juveniles, 13 subadults, and 16 adult SGH; 26 males and 27 females) over a period of 9 years. Antibody titers to avian avulavirus 1 in sera were monitored by a hemagglutination inhibition test. Protective titers were generated with 3/6 vaccine regimes tested in the SGH. The highest vaccine titers were established in birds vaccinated with the Ulster strain in the conjunctiva and followed with an intramuscular Struvac injection (mean log2 titer 8.6 ± 2.6) booster. Our aim was 1) to assess whether optimal vaccination protocols could be developed and 2) to then be able, by oral administration, to remove the need to recapture free-roaming, reintroduced birds to administer the initial vaccine or booster, thus remove the threat or mortality associated with ND to this endangered avian species in both captive birds and birds released back into the wild.

The southern ground hornbill, Bucorvus leadbeateri, is on the IUCN Red List of Threatened Species as a ‘Vulnerable’ species with a decreasing population. Despite a myriad of threats, including loss of nesting sites, accidental poisoning and persecution, there has been no detailed study of the southern ground hornbill in Zimbabwe. We collected data on nest sites and usage for 42 nests over three breeding seasons in the communal areas surrounding the Matobo National Park. For the active nests in the breeding seasons of 2008/9 and 2009/10 the mean nearest neighbour distances were 4.41 km and 3.53 km, respectively. Most nests were found in granite crevices (67%) while the remainder were found in five different tree species. Most nests (90%) were in areas of subsistence crop farming, the remainder (10%) were found in forests and open savannas. The high breeding density of the southern ground hornbill in the communal areas surrounding the Matobo National Park in Zimbabwe could be attributed in part to traditional Ndebele culture which, for the most part, protects this species. Food also appears to be relatively abundant under communal farming conditions.

Determining the range of a species and exploring species--habitat associations are central questions in ecology and can be answered by analyzing presence--absence data. Often, both the sampling of sites and the desired area of inference involve neighboring sites; thus, positive spatial autocorrelation between these sites is expected. Using survey data for the Southern Ground Hornbill (Bucorvus leadbeateri) from the Southern African Bird Atlas Project, we compared advantages and disadvantages of three increasingly complex models for species occupancy: an occupancy model that accounted for nondetection but assumed all sites were independent, and two spatial occupancy models that accounted for both nondetection and spatial autocorrelation. We modeled the spatial autocorrelation with an intrinsic conditional autoregressive (ICAR) model and with a restricted spatial regression (RSR) model. Both spatial models can readily be applied to any other gridded, presence--absence data set using a newly introduced R package. The RSR model provided the best inference and was able to capture small-scale variation that the other models did not. It showed that ground hornbills are strongly dependent on protected areas in the north of their South African range, but less so further south. The ICAR models did not capture any spatial autocorrelation in the data, and they took an order, of magnitude longer than the RSR models to run. Thus, the RSR occupancy model appears to be an attractive choice for modeling occurrences at large spatial domains, while accounting for imperfect detection and spatial autocorrelation.

This study investigates problem solving in one northern ground hornbill (Bucorvus abyssinicus) and two southern ground-hornbills (Bucorvus leadbeateri) in a horizontal string-pulling task. In five conditions, two strings were stretched out on the ground and subjects had to pull the end of the string which was properly connected to an out-of-reach food reward. Two subjects succeeded above chance in choosing a rewarded string over an unrewarded one (parallel and converged conditions), and continued pulling longer strings when the reward did not immediately move closer (coiled condition). One bird additionally understood which string was physically connected to the reward (contact condition). Although this study is preliminary, it highlights the necessity to extend research on physical cognition to other large-brained avian orders in order to better understand the underlying ecological and social selection pressures involved.

Development Of The Rhythmically Coordinated Duet Of A Bird Species (Southern Ground Hornbills, Bucorvus leadbeateri)

SummaryThe provision of artificial nests can improve the conservation status of threatened bird species that are limited by nest-site availability. The shortage of natural cavity nesting sites is one factor limiting the population growth of the Southern Ground Hornbill Bucorvus leadbeateri. In an 1,800 km2 study area in north-eastern South Africa, 31 wooden nest-boxes were installed during 2002–2015. We investigated the relationships between nests, as well as environmental and social factors, with breeding. Generalised linear mixed models were fitted to the observational data and identified positive relationships between breeding attempts and each of home range size and the previous year’s rainfall; as well as positive relationships between breeding success (amongst the groups that attempt breeding) and each of earlier breeding, nest height and thickness of the nest cavity wall. The provision of nest-boxes increased the number of breeding groups and although breeding success also increased initially, it later declined as the density of breeding groups increased above 20 groups. Although nest-boxes alone did not increase overall breeding success, they are an effective conservation tool to enhance the population of Southern Ground Hornbills if spaced optimally, to enhance reproductive output in areas where suitable nest-sites are scarce or lacking.

This paper summarizes current knowledge and outlines future work on the breeding biology of Southern Ground Hornbill Bucorvus leadbeateri in Zimbabwe. All available records since 1900 were analysed, including casual reports by members of BirdLife Zimbabwe and published records. Estimates were made for the start and end of the breeding season, group sizes, clutch size and productivity levels, together with an assessment of preferred habitats and nest-tree species. There is a need for intensive fieldwork to determine aspects of breeding biology such as incubation and nestling periods. Particularly important for sound management and conservation strategies is relative breeding success in different land-tenure systems. The author has started work in a communal area 40 km south of Bulawayo city; land-use systems such as new resettlement areas, commercial farms and protected areas remain to be studied.