Southern Ground-Hornbill conservation
Southern Ground-Hornbills Bucorvus leadbeateri are large, group-living birds which require large territories and relatively undisturbed areas with large trees for breeding and roosting. These two requirements are increasingly rare, given high rates of habitat destruction during the past century which has accelerated in recent decades. Southern Ground-Hornbills have experienced a two-thirds reduction in their national range and presumably population size in the past 100 years and are thus considered globally Vulnerable, having been up-listed to Endangered in South Africa. A long-term study at the Fitz, initiated in 2000, has been investigating their habitat use, reproductive success, natal and breeding dispersal. Recently, we started investigating their behaviour in more detail, specifically how individuals contribute to vital group functions such as territory defence and reproduction.
One of the main motivations at the origin of this research programme was to assess whether artificial nests were an alternative to natural cavities, which have become increasingly scarce. Our study area is the Associated Private Nature Reserves (APNR) covering 200 000 ha adjacent to the central Kruger National Park. The nest boxes proved successful, with 12-15 of the 20 groups that were provided with nest boxes attempting to breed each year.
This project is closely linked to the Mabula Ground-Hornbill Project. As part of this collaboration we provide the second-hatched chicks that invariably die of starvation in the wild from our population, to be captive-reared and later released in new areas.
The current focus of the project is on better understanding the species’ social structure and individual contributions to breeding success and territory defence. MSc student Kyle-Mark Middleton is investigating these questions under the supervision of Dr Rita Covas, Prof. Claire Spottiswoode and Dr Fanny Rybak. Kyle has obtained many hours of recordings of the different groups’ dawn chorus and has travelled to Paris to learn how to analyse the vocalisations with Fanny Rybak. The first results reveal intriguing differences between the sexes, and among the vocalisations of different individuals. The next step is to do play-back experiments to assess if the birds also perceive these vocalisations as different. These experiments were planned for the beginning of the breeding season, but anomalous weather with very late rains and high temperatures led to a delayed onset of breeding, and only a small number of groups attempted to breed. The play-back experiments have therefore been postponed to the following season.
Activities in 2018
- Kyle Middleton completed the first year of his MSc degree researching the breeding behaviour and vocalisations of the groups in the APNR allowing him to upgrade to a PhD degree in early 2019.
- Kyle travelled to Paris, France to join Fanny Rybak, where he was introduced to group vocalisation analysis. Initial analysis of the vocalisations (Figure 1) suggest that different territorial groups have unique ‘signatures’, and that male and female calls are performed at different frequencies.
- The first playback experiments were conducted to investigate whether groups are able to recognise neighbour groups from stranger groups through vocalisations.
- Increased efforts were continued to identify individuals by non-invasive techniques such as the use of camera-traps to photograph the birds’ face and obtain distinctive individual features of their bill or cask shape, red pouch, ‘side-burns’, etc. This will be used to study individual contributions to nestling feeding.
- Camera traps were placed in camouflaged boxes at five nests before the breeding season began which record birds provisioning food at the nest (Figure 2).
- Initial camera trap analysis shows that adult males contribute more to the feeding of the incubating female and chick than sub-adult helpers. It also appears that the female plays little part in feeding the chicks once she has stopped incubating.
- Genetic sample collection for known individuals is continuing through non-invasive methods, such as from shed feathers, the collection of fresh faeces when following groups and at roosts, and by swabbing eggs. This is to determine relatedness between individuals and how this influences investment in cooperative behaviour.
- Kyle presented a poster and speed-talk at the African Bioacoustics Conference in Cape Town on the vocalisations and individual contributions of the ground-hornbills.
- Kate Carstens had three papers from her PhD on breeding success, the timing of breeding and natal dispersal accepted for publication in the Journal of Ornithology, Bird Conservation International and Ostrich.
- The 2017/18 breeding season saw 14 active nests with nine chicks successfully fledged and three second-hatched chicks were harvested for the reintroduction programme.
- Egg candling was used for the first time to provide a more accurate estimate of the hatch date for harvesting and methods are being developed to sex birds whilst still in the egg.
- The project saw its 100th chick fledge from anartificial nest in the APNR since its establishment in 2000.
- The APNR has contributed 41 hatched chicks to the reintroduction programme.
- Ongoing repairs to and replacement of artificial nest boxes ensure that ground-hornbills can continue to thrive in an area which has a paucity of natural nest cavities.
- The TV show 50/50 featured the combined efforts to conserve the ground hornbill species.
Rob Little and Kyle Middleton participated in developing a Biodiversity Management Plan (BMP) for the Southern Ground-Hornbill with the Department of Environmental Affairs (DEA), relevant provincial conservation agencies and other stakeholders during May 2018 which will be implemented in collaboration with the DEA and SANBI.
Impact of the project
This project has provided a significant contribution to the demographic gains of the Southern Ground-Hornbill population at the APNR as a result of the installation of artificial nests and has demonstrated the efficacy of these nest boxes as a conservation tool, particularly in areas that have a shortage of large trees with natural cavities. These results contributed to the national Southern Ground-Hornbill Species Action Plan and to the Southern Ground-Hornbill Reintroduction Plan and assist with their implementation. Rob Little represents the Fitz on the national Southern Ground-Hornbill Working Group and is also Vice Chairman of the Mabula Ground-Hornbill Project management board. During 2018, the project gave five presentations to the general public to create awareness and published four articles in the magazine Klaserie Chronicle which is distributed to surrounding private reserves and the greater Hoedspruit community. The project has also gained interest from reserves surrounding the APNR which are showing increased attention towards the species and their conservation.
DST-NRF CoE grant; The Foundation for Science and Technology FCT, Portugal; Associated Private Nature Reserves; Senelala Estates.
Dr Rita Covas (FIAO, UCT and CIBIO, U.Porto)
Prof. Claire Spottiswoode (FIAO, UCT)
Dr Fanny Rybak (U. Paris-Sud, France)
Dr Rob Little (FIAO, UCT)
Students: Kyle Middleton (MSc, UCT).
Research Assistant: Carrie Hickman.