Barn Owl Roadway Mortality: Understanding Why More Females Than Males are Involved
Dr. Jim Belthoff
Barn owls (Tyto alba) are the most widespread of the owl species as they are found worldwide. They play an important role in monitoring rodent populations and they serve as good indicators of a healthy environment with a large biodiversity. Roadways are a relatively new addition to the landscape and though the full impact on wildlife is not fully known, recent data suggests that roadways are negatively impacting many wildlife populations- including barn owls. Roadways drastically change the landscape by damaging wildlife habitats, increasing habitat fragmentation, aiding in the dispersal of invasive plants, and directly colliding with animals. To better understand this phenomenon, we studied how roadways impact the movement and flight behavior of Barn Owls (Tyto alba) in Southern Idaho. Animals that have adapted to avoid oncoming traffic are impacted less. Barn owls however have been known to not react to roads. This means that historically they have not been found to recognize roadways and vehicles as a threat and therefore do not frequently avoid them. This results in a high roadway mortality rate.
We fitted 27 barn owls in Southwest Idaho with GPS data loggers that collected data on the owl's location, flight speed, and altitude. Data was collected for multiple nights in December 2019 and 2020. It was found that males are more likely to cross roadways within those months. However, the current literature suggests that females have a higher rate of roadway mortality regardless of the time of year (Boves and Belthoff, 2012). It was concluded that male barn owls travel more per night than females and subsequently cross more roads than females. However, males and females did not have significant differences in roads crossed per km traveled. There is also no significant difference between the distance from roads- males do not seem to be avoiding roads more than females. It’s possible that males are avoiding oncoming traffic because they are more agile due to their smaller size. It is also possible that there are more females on the landscape making it appear that there is higher mortality of females because there are more females available.
Young, Nicole; Belthoff, Jim; and Busby, Brian, "Barn Owl Roadway Mortality: Understanding Why More Females Than Males are Involved" (2022). 2022 Undergraduate Research Showcase. 102.