The effects of shrub encroachment on bird occupancy vary with land use in an African savanna. (18th July 2020)

• Record Type: Journal Article
• Authors: Stanton, R. A.; Fletcher, R. J.; Sibiya, M.; Monadjem, A.; McCleery, R. A.
• Is Part Of: Animal conservation. Volume 24:Number 2(2021)
• Page Start: 194
• Page End: 205
• Publication Date: 2020-07-18
• Subjects: global change synergies -- land‐use change -- occupancy models -- savannas -- shrub encroachment -- trait‐based ecology; Conservation biology -- Periodicals; Wildlife conservation -- Periodicals; Conservation de la biodiversité; Conservation de la faune; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); 333.95416
• DOI: 10.1111/acv.12620
• Languages: English
• ISSNs: 1367-9430

Abstract

Abstract: Land‐cover and land‐use change are major drivers of global biodiversity loss. Savannas are experiencing shrub encroachment and land‐use changes that affect animal communities, yet how the effects of shrub encroachment vary with land use remains unclear. We also need to determine which species traits explain the effects of shrub encroachment and land‐use changes to identify potential drivers of community change and predict species' responses to conservation efforts. We sampled birds across gradients of shrub encroachment and land use (protected savanna, pastures, homestead lands, and sugarcane) in the lowveld savanna of Eswatini to: (1) test for the effects of shrub encroachment, land‐use change, and their potential synergies on the occurrence of 48 species of birds; and (2) determine which species traits (those associated with nesting, foraging, or vulnerability to predation) explained species' associations with shrub encroachment and land‐use change. We used Bayesian multispecies occupancy models to account for imperfect detection, interpret species responses, and understand the effects of species traits. We found evidence for community‐wide synergies between shrub encroachment and land‐use effects on birds that varied with species' diets. Agricultural intensification had negative effects on the occurrence of most species examined, while shrub cover typically had positive effects which were stronger in pastures and homestead lands than in protected areas. The negative effects of land‐use change were greatest for insectivores and cavity nesters, whereas insectivore occurrence increased with shrub cover, collectively indicating that nesting and foraging traits best explained species responses to land‐use and land‐cover change in the region. Our results suggest that shrub cover management for bird conservation should vary with land use: shrubs could be thinned in protected areas without reducing bird occupancy but shrubs in homesteads should be retained. Abstract : We tested whether the effects of shrub encroachment on bird occurrence in lowveld savanna, Eswatini varied with land‐use intensity. We found that shrub encroachment promoted bird occurrence most strongly in homesteads and had weaker positive effects in pastures. Agricultural land uses had negative effects on bird occurrence that increased with land‐use intensity. Species diet, nesting substrate, and body mass explained species' responses to both land use and shrub encroachment, e.g., insectivores were less likely to occur in homesteads, but were positively associated with shrub encroachment. We suggest that shrubs in homesteads be retained to promote bird occurrence, which may be of particular benefit to insectivorous species that can deliver ecosystem services to farmers. Photo: Black‐backed Puffback, Dryoscopus cubla, an insectivorous species that responded negatively to agriculture and positively to shrub encroachment (taken by Hillary Carter).