Data from: Coexistence of three sympatric cormorants (Phalacrocorax spp.); partitioning of time as an ecological resource

Resource partitioning is well-known along food and habitat for reducing competition among sympatric species, yet study on temporal partitioning as a viable basis for reducing resource competition is not empirically investigated. Here, I attempt to identify the mechanism of temporal partitioning by intra and interspecific diving analyses of three sympatric cormorant species at different freshwater wetlands around the Delhi region. Diving results indicated that cormorants opted for a shallow diving; consequently, they did not face any physiological stress. Moreover, diving durations were linked with seasons, foraging time and foraging habitats. Intraspecific comparison suggested that cormorants spent longer time underwater in early hours of the day. Therefore, time spent for dive was higher in the forenoon than late afternoon, and the interspecific analysis also yielded a similar result. When P. niger and P. fuscicollis shared same foraging habitat, they tended to differ in their foraging time (forenoon / afternoon). However, when P. niger and P. carbo shared same foraging time, they tended to utilize different foraging habitats (lentic / lotic) leading to a mechanism of resource partitioning. Thus, sympatric cormorants effectively use time as a resource to exploit the food resources and successful coexistence.资源划分（resource partitioning）作为通过食物与生境维度降低同域物种（sympatric species）间竞争的经典生态学机制，已被学界广泛认知，但针对以时间划分（temporal partitioning）作为缓解资源竞争可行路径的实证研究仍较为匮乏。本研究通过对德里周边不同淡水湿地中3种同域鸬鹚的种内（intraspecific）与种间（interspecific）潜水行为开展分析，尝试阐明时间划分的潜在作用机制。 潜水行为监测结果显示，鸬鹚多选择浅潜模式，因此未承受明显的生理应激（physiological stress）。此外，潜水时长与季节、觅食时段及觅食生境（foraging habitat）显著相关。种内对比结果表明，鸬鹚在每日清晨的水下停留时长更长，因此其潜水耗时在上午显著高于午后，种间分析亦得到了一致的结果。 当P. niger与P. fuscicollis共享相同觅食生境时，二者的觅食时段（上午/午后）会出现显著分化；而当P. niger与P. carbo共享相同觅食时段时，二者则会选择不同的觅食生境（静水环境（lentic）/流水环境（lotic）），以此实现资源划分。 综上，同域鸬鹚可通过将时间作为一种资源进行分配，高效利用食物资源并实现种群的稳定共存。