perch-site selection in shrikes: effects of human disturbance in Poland and Loas

Background. Anthropogenic pressure, including hunting and habitat modification, is a major driver of behavioral variation in birds, particularly in regions differing in conservation regimes and human disturbance. Flight initiation distance (FID) is a widely used metric of antipredator behavior that reflects both immediate risk perception and longer-term behavioral adjustments to human activity. This study compares habitat selection and escape responses of two closely related species, the Red-backed Shrike (Lanius collurio) and the Brown Shrike (Lanius cristatus), occurring in regions with contrasting levels of human pressure: Central Europe (Poland) and Southeast Asia (Laos). We tested whether the two species differ in their use of perching sites relative to roads and built-up areas, and whether FID is shaped by proximity to human infrastructure and species identity.
Methods. Field data were collected in spring 2024 in agricultural and peri-urban landscapes in Poland and Laos. A total of 171 perching sites were recorded (102 Red-backed Shrikes and 69 Brown Shrikes). For each observation, flight initiation distance (FID), starting distance (SD), perch height, and distances to the nearest dirt road, asphalt road, and built-up area were measured. Determinants of FID were examined using linear models with log-transformed response variables. Model selection was based on an information-theoretic approach using AIC, and only models with ΔAIC ≤ 2 were retained for inference.
Results. Perch-site selection differed significantly between the two species. Brown Shrikes occurred at greater distances from built-up areas. FID was significantly greater in Brown Shrikes than in Red-backed Shrikes. Distance to the nearest built-up area had a negative impact, while the SD had positive impact on FID. These results indicate that shrikes inhabiting regions with higher hunting pressure exhibit stronger avoidance behavior and altered spatial responses to human infrastructure, highlighting the role of regional anthropogenic context in shaping antipredator behavior.

背景：包括狩猎与栖息地改造在内的人为压力，是驱动鸟类行为变异的核心因素，在保护制度与人类干扰水平存在差异的区域尤为显著。逃逸起始距离（Flight Initiation Distance，FID）是应用广泛的反捕食行为指标，可同时反映个体的即时风险感知与对人类活动的长期行为适应性调整。本研究针对两种近缘伯劳物种——红背伯劳（*Lanius collurio*）与棕背伯劳（*Lanius cristatus*），比较其栖息地选择与逃逸反应差异，研究区域分别为人类压力水平迥异的中欧（波兰）与东南亚（老挝）。我们旨在检验两个物种在相对于道路与建成区的栖息位点利用模式上是否存在差异，以及逃逸起始距离是否受人类基础设施的临近程度与物种身份所调控。
方法：2024年春季，研究团队在波兰与老挝的农业及城郊景观中开展野外数据采集工作。共计记录171个栖息位点，其中红背伯劳102个，棕背伯劳69个。针对每一次观测，我们记录了逃逸起始距离（FID）、起始距离（Starting Distance，SD）、栖息高度，以及到最近土路、沥青路与建成区的距离。采用对响应变量进行对数转换的线性模型分析逃逸起始距离的影响因子。模型选择基于信息论框架下的赤池信息准则（Akaike Information Criterion，AIC），仅保留ΔAIC ≤2的模型用于统计推断。
结果：两种伯劳的栖息位点选择存在显著差异。棕背伯劳的栖息位点距建成区的平均距离显著更远。棕背伯劳的逃逸起始距离显著大于红背伯劳。距最近建成区的距离对逃逸起始距离具有显著负向影响，而起始距离则对其具有显著正向影响。上述结果表明，栖息于更高狩猎压力区域的伯劳类物种表现出更强的避敌行为与对人类基础设施的空间响应改变，凸显了区域人为环境在塑造反捕食行为中的关键作用。