Mantintsilili Asekho, Geerts Sjirk, Seymour Colleen L, Coetzee Anina
Department of Conservation Management, Nelson Mandela University, George, South Africa.
South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont, South Africa.
Environ Manage. 2025 Apr;75(4):906-917. doi: 10.1007/s00267-024-02089-8. Epub 2024 Nov 16.
Supplementary sugar-water feeding offers nectarivorous birds a source of spatially concentrated food, as opposed to the dispersed food available in flowers. This could impact bird visits to native flowers and alter plant-bird mutualisms, particularly in young post-fire vegetation. This study examined the effects of sugar-water feeders on nectarivorous birds and their plant mutualists in young (burned 18 months previously) and transitional vegetation (burned 5 years previously). A supplementary feeding experiment was conducted at Grootbos Private Nature Reserve in South Africa, using sugar-water feeders when floral abundance was low (winter) and high (spring). We compared bird abundance and visitation rates to flowers before, during, and after feeder presence in both seasons. The use of sugar-water feeders by nectarivorous birds was inversely related to floral abundance, with 679 bird visits (6.94 ± 1.40 bird visitation rate per hour) to feeders in winter and only 90 visits (0.41 ± 0.16 visitation rate per hour) during spring. Bird visits were higher at flowers than at sugar-water feeders, in both seasons. Sugar-water feeders did not influence the visitation rate of sunbirds to flowers in both seasons, contrasting with findings from areas abutting suburbia, suggesting that feeder influence on bird visitation rate may not be apparent in areas with no history of sugar-water feeders. We find that low numbers of feeders do not necessarily compete with natural nectar resources but may instead provide birds with an additional food source, particularly when floral resources are low.
补充糖水喂养为食蜜鸟类提供了一种空间集中的食物来源，这与花朵中分散的食物形成对比。这可能会影响鸟类对本地花朵的访问，并改变植物与鸟类的互利共生关系，尤其是在火灾后的年轻植被中。本研究调查了糖水喂食器对年轻（18个月前被烧毁）和过渡性植被（5年前被烧毁）中的食蜜鸟类及其植物共生伙伴的影响。在南非的格罗特博斯私人自然保护区进行了一项补充喂养实验，在花期稀少（冬季）和丰富（春季）时使用糖水喂食器。我们比较了两个季节中喂食器出现之前、期间和之后鸟类的数量以及对花朵的访问率。食蜜鸟类对糖水喂食器的使用与花期丰富度呈负相关，冬季有679次鸟类访问喂食器（每小时6.94±1.40次鸟类访问率），而春季只有90次访问（每小时0.41±0.16次访问率）。在两个季节中，鸟类对花朵的访问都高于对糖水喂食器的访问。糖水喂食器在两个季节中均未影响太阳鸟对花朵的访问率，这与邻近郊区地区的研究结果形成对比，表明在没有糖水喂食器历史的地区，喂食器对鸟类访问率的影响可能不明显。我们发现少量的喂食器不一定会与天然花蜜资源竞争，反而可能为鸟类提供额外的食物来源，尤其是在花蜜资源匮乏时。
