Comparative Diet Analysis of Barn Owl (Tyto Alba) and Long- Eared Owl (Asio Otus) in a Habitat Island in North-Central Texas

Abstract

Predator-prey interactions often define the coexistence of species in space and time. In this research, we are filling a regional gap in knowledge of diet composition of the barn owl ( Tyto alba ) and the long-eared owl ( Asio otus ). The study was conducted at the Lewisville Lake Environmental Learning Area (LLELA), a patch of tallgrass prairie and post oak forest surrounded by areas with large anthropogenic modifications in north-central Texas. We examined the remains found in owl pellets collected September 2016 to March 2017. Small mammals, mainly rodents, constituted 100% of the T. alba and 98.5% of the A. otus diet. The hispid cotton rat ( Sigmodon hispidus ) was the most common prey detected (68.2% for T. alba and 89.0% for A. otus ). Diet niche breadth of T. alba was broader than that of A. otus (0.47 and 0.06, respectively), whereas mean prey size was smaller in the T. alba diet. Diet overlap between these owls was high (0.96), likely because they hunt similarly at night, on the wing, and the prey species have limited diversity. Most rodents eaten were juveniles and the sex ratio of prey was even in both owls’ diets. We highlight the value of conducting studies in such a unique and relatively pristine environment in the face of multiple threats. Additionally, although the occurrence of A. otus is rare and infrequent in the study area, we were still able to detect a difference in diet between the ubiquitous T. alba and A. otus.

Variation in small mammal food resource niche metrics of Western Barn Owl (Tyto alba) at the nesting pair and local population level

“…Although the Western Barn Owl have a wide food spectrum, especially due to the consumption of many potentially alternative preys in different geographical regions (Herrera 1974, Janžekovič & Klenovšek 2020, Romano et al 2020, this owl species was characterized as a small mammal specialist nocturnal raptor, because it has adapted mainly to the hunting and consumption of nocturnal small mammals (Rodentia and Eulipotyphla) in its range (Taylor 1994, Romano et al 2020. Studies on feeding habits and trophic niche breadth, and overlap variation of the Western Barn Owl at the level of intra-and interspecific feeding ecology are well known from several literature sources along its European (Pezzo & Morimando 1995, Bontzorlos et al 2005, Kitowski 2013, Petrovici et al 2013, Milchev 2016, North American (Marsk & Marti 1984, Marti et al 1993, Jiménez et al 2020, and South American (Trejo et al 2005, Nanni et al 2012 distribution range in temperate ecosystems. It is important to highlight the studies that evaluated the trophic niche pattern of the Western Barn Owl based on geographical variation or trends (Korpimäki & Marti 1995, González-Fischer et al 2011, Milana et al 2016, or along different gradients such as vegetative (Trejo & Lambertucci 2007), longitudinal-latitudinal (Leveau et al 2006), and urban-rural (Teta et al 2012, Hindmarch & Elliott 2015 gradients or in comparison of different landscape structures (Milchev 2015(Milchev , 2022, focusing on the importance of agricultural intensification in the resource utilization of Barn Owls (Veselovský et al 2017, Horváth et al 2018, Romanowski & Lesiński 2020, Jiménez-Nájar et al 2021.…”