ABSTRACT

Monitoring the vocal behavior of owls is challenging because of their nocturnal habits and limited vocal activity. Here, we evaluated the use of passive acoustic monitoring coupled with automated signal recognition software to monitor the spontaneous vocal activity of the Ferruginous Pygmy-Owl (Glaucidium brasilianum) over a complete annual cycle at five recording stations in the Brazilian Pantanal. The vocal behavior of this species was concentrated during the crepuscular periods, with highest vocal activity in the hours prior to sunrise. The Ferruginous Pygmy-Owl was vocally active throughout the year, but the species showed a peak of activity from June to August. Paired Ferruginous Pygmy-Owl males tend to perform territorial calls less often during the nestling period, which may partly explain the significant decrease in the vocal activity after August. Our results suggest that the breeding period of the species starts in June, and the nesting phase probably occurs from September onwards, when the wet season starts. The first rains in seasonal tropical areas are usually associated with an increase in food availability, which may explain the species´ breeding period onset. Future surveys aiming to monitor the species, avoiding the use of broadcast calls, should be performed before sunrise between June and August, when the vocal activity was maximal.

摘要

由于猫头鹰的夜间习性和有限的发声活动，监测猫头鹰的发声行为具有挑战性。在这里，我们评估了使用被动声学监测与自动信号识别软件相结合来监测铁质侏儒猫头鹰（Glaucidium brasilianum ）的自发发声活动）在巴西潘塔纳尔湿地的五个记录站的一个完整的年度周期中。该物种的发声行为集中在黄昏时期，日出前的几个小时发声活动最高。铁色侏儒猫头鹰全年发声都很活跃，但该物种在六月至八月期间表现出活动高峰。成对的铁色侏儒鸮雄性在雏鸟期往往较少发出领地叫声，这可能部分解释了八月后发声活动显着减少的原因。我们的研究结果表明，该物种的繁殖期从六月开始，筑巢期可能从九月开始，即雨季开始时。季节性热带地区的第一场降雨通常与粮食供应的增加有关，这可以解释该物种繁殖期的开始。未来旨在监测该物种的调查应避免使用广播呼叫，应在六月至八月之间的日出前进行，此时声音活动最为活跃。