Dietary comparison of coexisting barn owl (Tyto alba) and eagle owl (Bubo bubo) during consecutive breeding seasons

Abstract

Coexistence of predator species often depends on behaviours or preferences that result in spatio-temporal reduction of competition. In this study, the diets of coexisting barn owls (Tyto alba) and eagle owls (Bubo bubo) in an agricultural landscape of SE Bulgaria were compared. White-toothed shrews (Crocidura spp.), voles (Microtus spp.) and mice (Mus spp.) were the main prey of barn owl (86.3% by number, 81.2% by biomass) with significantly different frequencies in annual diets. The principle biomass (64.8 ± 6.2%) of the significantly different eagle owl annual diets comprised much heavier prey such as white-breasted hedgehog (Erinaceus roumanicus), European hare (Lepus europaeus) and non-passerine birds of wetlands and open habitats. The two owl species preferred and hunted on different prey size groups in the same territory, and this difference explained the low level of food competition (6.0 ± 3.6% diet overlap according to prey biomass). Voles were the only prey of the two owls with significantly different frequencies for the annual diets in intraspecies comparisons. The proportions of voles in both diets showed similar trends during the study. Eagle owl predation on barn owls was slightly affected by their coexisting breeding despite the high levels of food stress of eagle owl. These findings provide insight into how preying habits can predict successful coexistence of potentially competing predator species.

Spatial and temporal patterns in the diet of barn owl (Tyto alba) in Cyprus

“…Similarly, to the findings of this study, small mammals comprise the most important prey of the barn owl worldwide, although the prey composition and diversity varies according to the area [ [ 1 , 2 , 19 , 20 , 41 , 47 – 50 ]; among others]. Among small mammals, two genera of rodents were the major prey of the barn owl in Cyprus followed by two genera of insectivores.…”

“…Rats presumably compete with house mice [ 53 ], therefore various factors contributing to the local availability of the two species might have resulted in their use as prey. Insectivorous mammals have commonly been found as prey for the barn owl [ 1 , 4 , 10 , 48 – 50 , 54 ].…”

Food-niche pattern of the Barn Owl(Tyto alba)in intensively cultivated agricultural landscape

“…Since the classical trophic niche studies of owls (Marti 1974, Herrera 1974, Herrera & Hiraldo 1976) the food-niche difference of Barn Owls has been investigated in several approaches such as through comparative intra-and interspecific feeding ecology (Herrera & Jaksić 1980, Capizzi & Luiselli 1998, Leader et al 2010, Petrovici et al 2013, Milchev 2016, trophic guild structure (Jaksić & Delibes 1987, Jaksić et al 1993), long-term study of food composition (Marti 1988, 2010, Love et al 2000, along different geographical regions (Jaksić et al 1982, González-Fischer et al 2011, Milana et al 2016, and gradients (Leveau et al 2006, Trejo & Lambertucci 2007, Hindmarch & Elliott 2015, as well as the impact of disturbances (Jaksić et al 1997, Sahores & Trejo 2004) particularly dependence on growing agricultural activity and changes in farming practice (Love et al 2000, de la Peña et al 2003, Bontzorlos et al 2005, Marti 2010).…”

First evidence for carrion–feeding of Eurasian Eagle-owl (Bubo bubo) in Bulgaria

“…The high share of Northern White-breasted Hedgehog in food biomass as one of the most important prey is common in diets on Balkan Penninsula (Papageorgiou et al 1993, Simeonov et al 1998, Mihelič 2002, Sándor & Ionescu 2009, Milchev & Gruychev 2015, Milchev 2016 as in Central Europe as well (Glutz von Blotzheim & Bauer 1994). The larger catch of Northern White-breasted Hedgehogs and other prey from the preferred weight group as European Hares, rats, waterbirds and gallinaceous birds connects with good food supply.…”