Habitat preferences of Southern Ground-hornbills in the Kruger National Park: implications for future conservation measures

Leigh Combrink,André J Botha,Colleen T Downs,Hendrik J Combrink

doi:10.1038/s41598-020-73236-4

Leigh Combrink, André J Botha + Show 2 more

Open Access

https://doi.org/10.1038/s41598-020-73236-4

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Abstract

Understanding how a species utilises its habitat, and the processes that give rise to its movements and patterns of space use, is critical for its conservation. Southern Ground-hornbills Bucorvus leadbeateri are listed as Endangered in South Africa, as a result of habitat loss and persecution. The National Species Recovery Plan lists reintroductions as a suitable conservation action, but highlights “understanding the exact habitat requirements of Southern Ground-hornbills” as a knowledge gap. In this study, we used tracking data from six Southern Ground-hornbill groups (a total of 37,060 GPS locations) in the Kruger National Park to investigate their seasonal home range differences and habitat preferences. We used first-passage time analysis to determine the scale at which Southern Ground-hornbills concentrate their foraging efforts and whether specific movement behaviours were linked to habitat types. We found marked differences in seasonal home ranges, with all groups showing a range contraction during the breeding season. Grassland and open woodland habitat types were used throughout the year in accordance with their availability within the territory, with grassland, open woodland and dense thicket being favoured habitats for foraging. Our habitat preference results, based on longitudinal GPS data, allowed us to determine ideal habitat ratios (grassland:open woodland:low shrubland of 1.00:6.10:0.09 ha) to assist with the selection of suitable reintroduction sites for Southern Ground-hornbills. With an increasing number of species being threatened with extinction, reintroductions into suitable habitats may be a useful conservation mitigation measure. However, our findings highlight the importance of a thorough understanding of a species’ movement and space use prior to the selection of areas for reintroduction to ensure the establishment and sustainability of these species at these sites.

Highlights

With the advent of advances in satellite tracking technology and the accompanying improvements in analytical tools, the field of movement ecology has developed rapidly over the last decade[1,2,3]
Our results have demonstrated habitat preferences, such as the ratio of lowmedium woody cover to grassland, which influence the home range size, and the number of groups of Southern Ground-hornbills that can be supported in an area
Sufficient open woodland and grassland habitats are of primary importance and necessary to support the foraging requirements of Southern Ground-hornbills

Summary

Introduction

With the advent of advances in satellite tracking technology and the accompanying improvements in analytical tools, the field of movement ecology has developed rapidly over the last decade[1,2,3]. The use of tracking technology has allowed researchers to link movement patterns and relocation data with global information systems (GIS) mapping, habitat and environmental variables, providing a useful way of determining the influence of habitat and environmental features on animal movement[6,11] Understanding these patterns of movement and habitat use and relating these to environmental variables and habitat heterogeneity will assist in modelling and predicting species’ home ranges in different regions and determining their minimum habitat requirements[7]. Southern Ground-hornbills Bucorvus leadbeateri are large, terrestrial, carnivorous birds that inhabit savanna and bushveld habitats throughout much of Africa, south of the e quator[12] They are co-operative breeders, forming groups with an alpha breeding pair and up to nine helper birds, and they forage as a cohesive unit[12]. This plan highlighted several knowledge gaps for the species, one being an understanding of the habitat requirements of these birds, as well as important conservation initiatives that could be implemented, such as active relocations of groups to suitable areas within their historical distribution[17]

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