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Southern Ground-Hornbill conservation

Southern Ground-Hornbills Bucorvus leadbeateri are large, group living birds which require large territories and relatively undisturbed areas with large, old trees that have suitable breeding cavities. These two requirements are increasingly rare given the high rates of habitat destruction that have been ongoing for over a century and have accelerated in recent decades. Southern Ground-Hornbills (SGH) 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.

One of the main aims of this study was to assess whether artificial nest cavities were an alternative to natural cavities, which have become increasingly scarce. This project is also closely linked to the Mabula Ground-Hornbill Project (MGHP) and the national Ground-Hornbill Action Group who are our partners in implementing the national SGH Species Recovery Plan. The main study area is the Associated Private Nature Reserves (APNR), covering some 200 000 ha adjacent to the central Kruger National Park, and supporting over 20 ground-hornbill groups, of which 12-15 regularly attempt to breed. We have reproductive histories spanning a decade and have found that breeding success increases with group size and the amount of open habitat within 3 km of the nest site. A current focus is on obtaining a better understanding of the species’ social structure and individual contributions to breeding success and territory defence.

PhD student Kate Carstens graduated in December 2017 with a thesis on the effectiveness of artificial nests as a conservation tool. Kate found that artificial nests are readily used by the birds, significantly increasing the breeding population in the study area. Additionally, Kate’s research provided valuable insights into dispersal strategies of these birds, showing that, although males remain in the natal group for much longer than females, overall dispersal rates are similar for both sexes, unlike what was previously believed. The settlement decisions following dispersal appear to arise from opportunity rather than searching for a better territory, as neither territory quality nor group size affected settlement decisions.

While long-term data collection will continue to address unresolved questions such as what governs dispersal decisions, a new project is focusing on providing a better understanding of this species’ social structure. Kyle-Mark Middleton started an MSc study to investigate how individual group members contribute to vital group functions, such as territory defence and reproduction, two poorly understood topics. The project, supervised by Claire Spottiswoode and Rita Covas, has a strong emphasis on understanding the role of group vocalisations on territory defence. For this, Kyle will work with Fanny Rybak, an acoustics’ expert from the University of Paris-Sud, France.

Activities in 2017

  • Kyle Middleton registered at UCT for an MSc, researching the breeding behaviours and vocalisations of the groups in the APNR.
  • Carrie Hickman was appointed as a field assistant to help with the behavioural research and to continue the monitoring of breeding activity and foraging habits.
  • Vocalisations of 11 breeding groups were recorded throughout the APNR during their daily morning chorus.
  • Initial analysis of the vocalisations suggest that different territorial groups have unique ‘signatures’.
  • Increased efforts were made 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.
  • Camera traps were placed close to the nest entrances of three nests. The cameras were placed inside boxes that were built for extra camouflage and placed in the field before the breeding season began. The cameras take three photos along with a 30 second video of the birds when they go into the nest to provide food.
  • Genetic samples from known individuals, including incubating alpha females, continue to be collected through non-invasive methods, such as from moulted 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.

Highlights:

  • Kate Carstens was awarded a PhD for her thesis titled ‘Nest boxes as a conservation tool for the Southern Ground-Hornbill Bucorvus leadbeateri’.
  • Kate presented a paper at the International Hornbill Congress held in Borneo in May.
  • The second Southern Ground-Hornbill population and habitat viability assessment (PHVA) workshop was held at Mabula Private Game Reserve in August 2017. Nationwide actions were set in motion to conserve the species.
  • The 2016/17 season saw 14 active nests with eight chicks successfully fledged, and four second-hatch chicks were harvested for the wild-release programmes.
  • Since 2000, 98 chicks have fledged from artificial nests in the APNR, contributing 38 second-hatched chicks for the species’ Reintroduction Plan.
  • Thornybush Nature Reserve became part of the APNR, expanding the study area by 11 000 ha.
  • A new active natural nest was discovered on Thornybush Nature Reserve.
  • 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.
  • Six new artificial nests were installed, of which three were used by hornbills. One of these nests saw the first breeding attempt for a group of birds located on Jejane Private Nature Reserve.

Impact of the project

This project has provided a significant contribution to the demographic gains of the SGH population at the APNR as a result of the deployment of artificial nests in the reserve. More generally, the project 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 SGH Species Action Plan and to the SGH Reintroduction Plan and assist with the implementation of these plans. Rob Little and Kate Carstens represent the Fitz on the national SGH Action Group while Rob is also Vice Chairman of the MGHP management board. During 2017, the project gave seven presentations to the general public to help create awareness and published an article in the local magazine Klaserie Chronicle which is distributed to surrounding private reserves and the greater Hoedspruit community.

Key co-sponsors

The Foundation for Science and Technology FCT, Portugal; Associated Private Nature Reserves; Dow Southern Africa (Pty) Ltd; Senelala Estates.

Research team

Prof. Claire Spottiswoode (FIAO, UCT)
Dr Rita Covas (FIAO, UCT and CIBIO, U.Porto)
Dr Fanny Rybak (U. Paris-Sud, France)
Dr Rob Little (FIAO, UCT)

Students: Kate Carstens (PhD, UCT); Kyle Middleton (MSc, UCT).

Research Assistant: Carrie Hickman.