Birds invest time and resources in escape behaviors, thus changing their foraging strategies, habitat selection, and even reproduction. Flight initiation distance (FID) and the distance at which birds detect a threat, alert distance (AD), have been used as indicators of the ability of birds to detect potential predators. In this study we compared the two aforementioned measures of risk reaction for the House sparrow and the Orange-breasted bunting, two bird species inhabiting the same urban areas, and assessed if they were related with sex, flock size, and environmental factors. We performed generalized linear mixed models (GLMM) to explore the relationships between environmental factors and ADs and FIDs. Both behavioral responses were significantly lower for House sparrows. Although we did not find significant relationships between the assessed variables (sex, flock size, environmental factors) and bunting ADs and FIDs, we did find House sparrow males to be bolder (showing shorter ADs and FIDs), as well as larger ADs and FIDs for sparrows with increasing flock size. House sparrow ADs and FIDs were positively related with herbaceous plant cover and negatively related with minimum building height. In general, House sparrows showed to be bolder than Orange-breasted buntings, with differential responses of the sparrow related with sex, flock size, and different environmental factors. Having recorded bolder House sparrow males could be due to increases in aggressiveness related to the breeding season. Our results add to the lacking behavioral information available for the endemic Orange-breasted bunting and provide insights on the variation of the behavior of House sparrows in small urban areas.

中文翻译：

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对人宽容？评估与性别、鸡群大小和环境特征相关的两种鸟类的警报和飞行起始距离

鸟类在逃跑行为上投入了时间和资源，从而改变了它们的觅食策略、栖息地选择，甚至繁殖。飞行起始距离 (FID) 和鸟类检测到威胁的距离、警报距离 (AD) 已被用作鸟类检测潜在捕食者能力的指标。在这项研究中，我们比较了家麻雀和橙胸鹀这两种栖息在同一城市地区的鸟类的上述两种风险反应措施，并评估了它们是否与性别、鸡群大小和环境因素有关。我们执行广义线性混合模型 (GLMM) 来探索环境因素与 AD 和 FID 之间的关系。家麻雀的两种行为反应都显着降低。尽管我们没有发现评估变量（性别、鸡群大小、环境因素）与彩旗 AD 和 FID 之间存在显着关系，但我们确实发现家麻雀雄性更大胆（显示较短的 AD 和 FID），以及较大的 AD 和 FID用于增加鸡群大小的麻雀。麻雀 ADs 和 FIDs 与草本植物覆盖率呈正相关，与最小建筑高度呈负相关。一般来说，家麻雀比橙胸鹀更大胆，麻雀的不同反应与性别、鸡群大小和不同的环境因素有关。记录更大胆的家麻雀雄性可能是由于与繁殖季节相关的攻击性增加。