Evaluating raptor populations is challenging because of their low population densities and secretive breeding behavior. Barn Owls (Tyto alba) are particularly difficult to monitor given their nocturnal nature and irregular vocalization patterns. In an effort to help develop more effective survey protocols for locating breeding Barn Owls and for monitoring Barn Owl populations, we examined factors influencing Barn Owl detections and responses to broadcast surveys. We conducted 288 surveys at 33 different nest locations in 2013 and 2014 in Illinois, USA, and examined the influence of using call broadcasts, breeding stage, day of year, cloud cover, moon phase, time of night, wind speed, ambient noise, temperature, and the number of Barn Owls in proximity on detection rates. We detected Barn Owls on 11.2% of passive surveys and 49.4% of broadcast surveys; 97.6% of the detections during broadcast surveys involved individuals flying within 20 m of observers. Detections were more common earlier in the breeding season and in areas where density of known Barn Owl nests was greater, but these variables affected detections from broadcast and passive surveys similarly; other variables did not have meaningful associations with Barn Owl detections. These results suggest that broadcast surveys may be an effective approach for identifying areas where Barn Owls are breeding or for monitoring population trends.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.