Maximizing detection probability to optimize nocturnal bird surveys in large areas

Aim Our specific objectives were to (1) estimate probabilities of detection of each species, after taking into account survey-specific covariates, and (2) investigate the influence of site-specific covariates on owl and nightjar abundance, integrating effects of imperfect detection. Innovation We conceived a survey protocol to estimate probabilities of detection and estimates of abundance of owls and nightjars in a large area, the Basque Country, northern Spain. Main Conclusions Our results show that detection probability was strongly influenced by playback broadcast and by observer experience. Date irregularly affected species according to their reproductive periods, and we also found that vocal activity gradually diminished proportionally to the hour after sunset. Tawny owl (Strix aluco) was the most abundant and widely distributed species. Its abundance was positively related to forest areas (mainly pine timber forests) and decreased in large urban and agricultural areas. Open space ...研究目标：本研究的具体目标为：（1）在考虑调查特异性协变量的前提下，估算各物种的探测概率；（2）整合不完全检测的影响，探究样地特异性协变量对鸮形目鸟类与夜鹰类种群丰度的影响。研究创新：我们设计了一套调查方案，用于估算西班牙北部巴斯克地区这一大范围区域内鸮形目鸟类与夜鹰类的探测概率及种群丰度。主要结论：研究结果显示，探测概率显著受鸣唱回放与观测者经验的影响；调查日期会依据物种的繁殖周期对其产生不规则影响；我们还发现，鸣声活动会随日落后的时长成比例逐渐减弱。灰林鸮（Strix aluco）是种群丰度最高且分布最广泛的物种，其种群丰度与林地（主要为商品松林）呈正相关，在大型城市与农业区域则有所降低。开阔生境……