Votto Simon E, Schlesinger Christine, Dyer Fiona, Caron Valerie, Davis Jenny
Research Institute for the Environment and Livelihoods Charles Darwin University Casuarina Northern Territory Australia.
Centre for Applied Water Science University of Canberra Bruce Australia Capital Territory Australia.
Ecol Evol. 2023 Aug 3;13(8):e10396. doi: 10.1002/ece3.10396. eCollection 2023 Aug.
Interference competition has the potential to alter avian assemblages at long-lasting arid zone waterholes, particularly in a warming world, as more potentially aggressive species frequent these sites to drink. We used camera traps and observational surveys to investigate interference competition between terrestrial avian species at six long-lasting waterholes across three sampling seasons (two summers and one winter) within the MacDonnell Ranges Bioregion in central Australia. The proportion of individuals drinking for each of four dietary classes (granivores, nectarivores, omnivores, and insectivores) was modelled in relation to their abundance in the immediate waterhole habitat, which informed the potential for competition in each season. We then used the temporal overlap estimators to quantify the degree of competition between species at waterholes with species grouped into families (Meliphagidae, Ptilonorhynchidae, Estrildidae, and Rhipiduridae). We found the proportion of individuals drinking at waterholes was greatest during hot and dry periods, suggesting the potential for interference competition is greatest during these times. This was particularly the case for nectarivores where, in hot and dry conditions, the proportion of drinking individuals increased significantly as their abundance also increased in the waterhole habitat. We predicted that subordinate species would alter their activity periods to avoid competitive interactions with meliphagids (honeyeaters), however, we found there was a high degree of temporal overlap between all families sampled across all seasons. These results suggest subordinate species are unlikely to be excluded from long-lasting waterholes by potentially aggressive species, such as honeyeaters. However, some species may face trade-offs between foraging and accessing waterholes to stay hydrated as they shift their activity to avoid the hottest parts of the day during the summer months. Under global warming, extended hot and dry periods will likely create conditions where balancing energy and hydration requirements becomes increasingly difficult and results in the loss of body condition.
干扰竞争有可能改变长期存在的干旱地区水坑处的鸟类群落，尤其是在气候变暖的世界里，因为更多具有潜在攻击性的物种会频繁前往这些地方饮水。我们利用相机陷阱和观测调查，研究了澳大利亚中部麦克唐奈山脉生物区域内六个长期存在的水坑在三个采样季节（两个夏季和一个冬季）中陆地鸟类物种之间的干扰竞争。针对四类食性的鸟类（食谷鸟、食蜜鸟、杂食鸟和食虫鸟），我们建立模型分析了它们在水坑附近栖息地的数量与其饮水个体比例之间的关系，以此了解每个季节的竞争潜力。然后，我们使用时间重叠估计器，对水坑处按科分类（吸蜜鸟科、园丁鸟科、梅花雀科和鸲鹟科）的物种间竞争程度进行量化。我们发现，在炎热干燥时期，水坑处饮水的个体比例最高，这表明在这些时期干扰竞争的可能性最大。食蜜鸟的情况尤其如此，在炎热干燥的条件下，随着它们在水坑栖息地数量的增加，饮水个体的比例也显著上升。我们预测从属物种会改变其活动时间，以避免与吸蜜鸟发生竞争互动，然而，我们发现所有采样科在所有季节的时间重叠程度都很高。这些结果表明，从属物种不太可能被吸蜜鸟等具有潜在攻击性的物种排除在长期存在的水坑之外。然而，一些物种在夏季转移活动以避开一天中最热时段时，可能会在觅食和前往水坑获取水分以保持水分之间面临权衡。在全球变暖的情况下，延长的炎热干燥时期可能会创造出这样的条件，即平衡能量和水分需求变得越来越困难，并导致身体状况下降。
