城市地区呈指数级扩张,引领更多生活在城市环境中的野生动物物种。城市环境特征,例如人为干扰,引起许多野生动物的压力,并已被证明会影响一些认知特征,如创新的解决问题的表现。然而,因为不同的认知特征有共同的认知过程,城市环境特征可能会直接和间接影响相关的认知特征(涟漪效应假说)。我们在居住在11个具有不同城市环境特征(直接人为干扰,间接人为干扰,绿色覆盖区域和松鼠种群数量)。这些松鼠是创新者,他们以前反复解决了食物提取任务(原始任务)。这里,我们研究了城市环境特征是否以及如何直接和间接影响两个相关认知特征的表现,概括和(长期)记忆。泛化任务要求创新者在解决类似但新颖的问题时应用学到的成功解决方案。记忆任务要求他们在延长的一段时间后回忆原始任务的学习解决方案。一些选定的城市环境特征直接影响了任务绩效,在人口层面(地点)和个人层面。城市环境特征,例如增加直接和间接的人为干扰,降低了在总体(站点)级别上解决泛化任务或内存任务的成功比例。直接人为干扰的增加和绿色覆盖率的减少提高了各个级别的解决效率。我们还发现了城市环境特征之一的间接影响,间接人为干扰,在概括任务中,但不是内存任务。这种效应仅在个体水平上可见,而在人群水平上却没有;间接人为干扰减少了最初的潜伏期,然后减少了成功的推广延迟。我们的结果部分支持涟漪效应假说,表明城市环境特征是松鼠的压力源,并且比以前显示的对塑造认知表现的影响更大。一起,这些结果提供了对支持野生动物适应城市环境的认知特征的更好理解。
Urban areas are expanding exponentially, leading more species of wildlife living in urban environments. Urban environmental characteristics, such as human disturbance, induce stress for many wildlife and have been shown to affect some cognitive traits, such as innovative problem-solving performance. However, because different cognitive traits have common cognitive processes, it is possible that urban environmental characteristics may directly and indirectly affect related cognitive traits (the ripple effect hypothesis). We tested the ripple effect hypothesis in urban Eurasian red squirrels residing in 11 urban areas that had different urban environmental characteristics (direct human disturbance, indirect human disturbance, areas of green coverage and squirrel population size). These squirrels were innovators who had previously repeatedly solved a food extraction task (the original task). Here, we examined whether and how urban environmental characteristics would directly and indirectly influence performance in two related cognitive traits, generalisation and (long-term) memory. The generalisation task required the innovators to apply the learned successful solutions when solving a similar but novel problem. The memory task required them to recall the learned solution of the original task after an extended period of time. Some of the selected urban environmental characteristics directly influenced the task performance, both at the population level (site) and at individual levels. Urban environmental characteristics, such as increased direct and indirect human disturbance, decreased the proportion of success in solving the generalisation task or the memory task at the population (site) level. Increased direct human disturbance and less green coverage increased the solving efficiency at individual levels. We also found an indirect effect in one of the urban environmental characteristics, indirect human disturbance, in the generalisation task, but not the memory task. Such an effect was only seen at the individual level but not at the population level; indirect human disturbance decreased the first original latency, which then decreased the generalisation latency across successes. Our results partially support the ripple effect hypothesis, suggesting that urban environmental characteristics are stressors for squirrels and have a greater impact on shaping cognitive performance than previously shown. Together, these results provide a better understanding of cognitive traits that support wildlife in adapting to urban environments.