Artificial nectar feeders reduce sunbird abundance and plant visitation in Cape Fynbos adjacent to suburban areas

Anina Coetzee,Claire N Spottiswoode,Colleen L Seymour,Monique Du Plessis

doi:10.1016/j.gecco.2021.e01706

Anina Coetzee, Claire N Spottiswoode + Show 2 more

Open Access

https://doi.org/10.1016/j.gecco.2021.e01706

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Abstract

Globally, people feed wild animals to interact with nature. Attracting nectarivorous birds to gardens using artificial nectar feeders is increasingly popular, yet little is known about its influence on birds and the plants they pollinate. We investigated effects of nectar feeders on African birds and their plant mutualists, by conducting feeding experiments in gardens and natural vegetation along the suburban edge of the Cape Peninsula, South Africa. We compared relative abundance and local distribution patterns of nectar-specialist, nectar-opportunist and non-nectarivore bird species between feeder and control treatments. We then tested whether nectar feeders in gardens affected visitation rates to two sunbird-pollinated Erica species in neighbouring vegetation compared to control sites. Nectar feeders increased the density of nectarivores (but not non-nectarivores) in gardens but decreased their density in neighbouring vegetation, even in winter when floral abundance was high. These changes in sunbird distribution patterns had no detectible influence on visitation rates to E. abietina, but decreased visitation to E. plukenetii flowers by on average 16% at least up to 300 m of gardens with feeders. Thus, although supplementary nectar feeding may have conservation value for nectarivorous birds by reducing their urban sensitivity, it can inadvertently interfere with bird-plant pollination networks by competing with native flowers for birds’ attention.

Highlights

Exposure to nature can promote human wellbeing and overall health (Cox and Gaston, 2016; Taylor et al, 2018)
Season had no effect on density of nectarspecialists, despite higher floral abundance in natural vegetation during winter
We found altered local distributions of nectarivorous birds along the suburban edge of the Cape Peninsula, South Africa, regardless of season

Summary

Introduction

Exposure to nature can promote human wellbeing and overall health (Cox and Gaston, 2016; Taylor et al, 2018). As humanity becomes increasingly urban and people concentrate in cities with impoverished biodiversity, there is progressive disengagement with the natural world (Seymour et al, 2020a). There is a growing interest in creating wildlife-friendly urban areas (Maruyama et al, 2019; Meehan et al, 2020; Mnisi et al, 2021). In addition to establishing diverse native plant assemblages (Evans et al, 2009; Mnisi et al, 2021), people use supplementary resources such as feeders and water baths to attract animals to gardens (Evans et al, 2009; Fuller et al, 2008). Wild animal feeding has become one of the most common forms of wildlife interactions in many countries (Cox and Gaston, 2018)

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