Data from: Urban nectarivorous bird communities in Cape Town, South Africa, are structured by ecological generalisation and resource distribution

Biological communities are increasingly faced with novel urban habitats and their response may depend on a combination of biological and habitat traits. The response of pollinator species to urban habitats are of particular importance because all species involved in the pollination mutualism may be affected. Nectarivorous bird communities worldwide show varying tolerances to urban areas, but studies from Africa are lacking. We investigated nectarivorous bird communities in a medium-sized South African city and asked which biological and garden traits best predict the community assembly of specialist and opportunistic nectarivorous birds. Information was collected on garden traits and the frequency of nine nectarivorous bird species for 193 gardens by means of a questionnaire. Information on biological traits of birds was obtained from published literature. Habitat generalism and tree nesting were identified as the most important biological traits influencing bird occurrence in gardens. A greater diversity of indigenous bird-pollinated plants and the presence of sugar water feeders increased the numbers of nectar specialist birds and species richness of nectarivorous birds. While bird baths increased the species richness of nectar specialist birds, opportunistic birds’ urban adjustment was further facilitated by large vegetated areas in gardens and limited by the distance to the nearest natural habitat. In conclusion, though some biological traits and dispersal barriers seem to limit urban adjustment, a combination of natural and artificial nectar resource provisioning could facilitate this adjustment.生物群落正日益面临新兴城市生境，其响应模式可能由生物性状与栖息地性状共同决定。传粉互利共生（pollination mutualism）涉及的所有物种均可能受到影响，因此传粉物种类群对城市生境的响应尤为关键。全球范围内的食蜜鸟（nectarivorous bird）群落对城市区域的耐受程度存在差异，但目前尚缺乏来自非洲的相关研究。 本研究以南非一座中等规模城市的食蜜鸟群落为研究对象，旨在明确哪些生物性状与庭院性状可最优预测特食性与兼食性食蜜鸟的群落构建过程。研究人员通过问卷调研，收集了193个庭院的生境性状数据以及9种食蜜鸟类的出现频率信息；鸟类生物性状数据则取自已发表的文献资料。 研究结果显示，栖息地泛化性（habitat generalism）与树栖筑巢（tree nesting）是影响鸟类在庭院中出现的最重要生物性状。本土鸟类传粉植物的多样性越高，以及人工糖水喂食器（sugar water feeders）的存在，均可提升特食性食蜜鸟的种群数量与食蜜鸟类的物种丰富度。尽管鸟类饮水沐浴池（bird baths）可提升特食性食蜜鸟的物种丰富度，但庭院内的大型植被区域可进一步促进兼食性食蜜鸟的城市适应，而其适应过程则会受到与最近自然栖息地距离的限制。 综上，尽管部分生物性状与扩散屏障（dispersal barriers）似乎会制约食蜜鸟的城市适应过程，但天然与人工蜜源资源的协同供给可有效促进这一适应过程。