Decreased vigilance or habituation to humans? Mechanisms on increased boldness in urban animals

Increased boldness is one of the most prevalent behavioral modifications seen in urban animals, and is thought to be a coping response to anthropogenic environmental alterations. Most previous studies have shown enhanced boldness manifested as changes in responses to humans approaching, such as reductions in flight initiation distance (FID). However, this includes two confounding factors related to “boldness”, i.e., reduction of vigilance and habituation to humans. Confounding these totally different processes could lead to our misunderstanding of urban adaptation and how to properly manage urban wildlife. Here, we propose a simple framework to separate the two processes using two flight distance measures toward different approaching threats. We considered that the distance at which targeted individuals noticed an approaching object (i.e., alert distance, AD) was related to vigilance, whereas FID represented risk assessment, which is related to habituation. We applied a predictive frame...城市野生动物中最为普遍的行为改变之一便是大胆行为的提升，这类行为被认为是应对人为环境改变的适应性应对反应。过往多数研究表明，大胆行为的增强体现为动物对人类靠近的反应变化，例如逃逸起始距离（flight initiation distance, FID）的缩短。然而，此类研究存在与“大胆性”相关的两个混淆因素，即警觉性降低与对人类的习惯化。将这两种完全不同的过程混同，可能会导致我们对城市适应性的认知出现偏差，也会影响城市野生动物的科学管理。在此，我们提出一套简易分析框架，通过针对两类不同逼近威胁的逃逸距离测量来区分这两个过程：我们认为，目标个体察觉到逼近物体时的距离（即警觉距离（alert distance, AD））与个体警觉性相关，而逃逸起始距离则代表与习惯化相关的风险评估。我们将此预测性框架应用于……