Diet Of Barn Owl Research Articles

Barn Owls (Tyto alba Scopoli, 1769) in the Saharan Region of Algeria (Souf): Valuable Predators for Rodent Control in Agriculture

Background: Barn Owls (Tyto alba Scopoli, 1769), which are nocturnal birds of prey, play a crucial role in controlling rodent populations that damage crops. They are valuable allies for farmers because they can effectively hunt small rodents. In Algeria, the Barn Owl is represented by two subspecies, Tyto alba alba and Tyto alba guttata. Methods: This study focuses on the Barn Owls' diet in the Saharan region, specifically in the Souf region, characterized by a dry climate. The research examines the contents of the Barn Owl's reject balls, which are regurgitated, to determine their diet. Result: The study reveals that each reject ball contains 1 to 9 prey items. The researchers identified 23 prey species, with rodents being the most abundant, making up 88.3% of the diet. The most commonly found prey species in Barn Owl balls are G. gerbillus, G. campestris, M. musculus, G. nanus and G. tarabuli. Overall, the Barn Owl's diet in the Saharan region is crucial for maintaining ecosystem balance by controlling rodent populations.

Dietary Shift in a Barn Owl (Tyto alba) Population Following Partial Abandonment of Cultivated Fields (Central Apennine Hills, Italy).

While most studies focused on the impact of intensive agriculture on the barn owl's diet, little is known about the effect of cropland abandonment. We compared the taxon composition/evenness and feeding guild structure of small mammal prey identified in pellets collected before (2004) and after (2012) the abandonment of 9% of cultivated fields within a cultural landscape. Data on prey abundance per pellet were analysed through non-metric multidimensional scaling and permutational, paired tests. Prey taxon evenness in 2012 was significantly lower than in 2004. That induced a shift in prey taxon composition as indicated by the significantly lower dietary similarity compared with the random expectation. The increasing and declining abundance of Murinae and Crocidurinae, respectively, had the largest contribution to the differentiation of the diet spectrum. Insectivorous prey was significantly more abundant in 2004 compared to 2012, while the opposite was true for omnivorous prey. Our results suggest that even a small fraction of abandoned crops in the landscape might induce a detectable shift in the barn owl's food niche. The dietary effects are similar to those observed after agricultural intensification, that is, an increase in the abundance of generalists to the detriment of specialist mammal prey.

Diet and reproductive outputs of common barn-owl (Tyto alba) during the common vole (Microtus arvalis) outbreak and crash

Diet and reproductive outputs of common barn-owl (Tyto alba) during the common vole (Microtus arvalis) outbreak and crash

Shrew Communities in Mediterranean Agro-Ecosystems of Central Greece: Associations with Crop Types, Land Uses, and Soil Parameters.

Shrew communities play a crucial role in a diverse range of natural, urban, and agricultural ecosystems. We used Barn owl diet analysis as the ideal proxy to assess small-mammal distribution patterns on large spatial scales. More than 10,000 pellets were analyzed from Thessaly, the largest agricultural prefecture located in central Greece. A total of more than 29,000 prey items were identified, one of the largest datasets used in similar analyses in Europe. Three discrete shrew species were present in Thessaly agricultural plains, central Greece (Güldenstädt's shrew Crocidura gueldenstaedtii, Bi-coloured shrew Crocidura leucodon, and Pygmy white-toothed shrew Suncus etruscus), which comprised a total of 7452 shrews, representing 25.64% of the total small-mammals' dataset. C. gueldenstaedtii and S. etruscus demonstrated strong associations with heavy argillaceous-clay soils and Vertisol soil types, whereas S. etruscus was also associated with non-irrigated land and non-intensive cultivated plots. C. leucodon demonstrated no significant associations to any environmental gradient and demonstrated habitat plasticity, most possibly shaped by existing resources and competition. Our study highlights the important insights gained from Barn owl diet analysis in respect of small-mammal assemblages on broad geographical scales, and the inclusion of soil parameters as drivers of habitat suitability and distribution patterns for small-mammal responses.

An inside "beak": Molecular analysis of swab samples reveals the seabird diet of invasive Barn Owls in Hawai'i.

Predation is an important species interaction to monitor when assessing an invasive species' impact on a particular ecosystem, but it can be difficult to observe and thus, fully understand. On Kaua'i island, invasive Barn Owls (Tyto alba) predate native seabirds, but difficult terrain in this region and the cryptic nature of owl predation make traditional monitoring of predation quite challenging. Using Barn Owls collected as part of removal efforts on Kaua'i and Lehua islands, we conducted DNA metabarcoding of owl digestive tracts to detect and determine seabird species they predate. We used a seabird-targeted 12s marker to sequence 112 swabs from 55 owls and detected 6 seabird taxa, including 2 ESA-listed seabirds-Hawaiian Petrel (Pterodroma sandwichensis) and Newell's Shearwater (Puffinus newelli), in 12 swabs from 11 owls (20% of sampled owls). Corresponding morphological assessment of owl stomach contents detected seabird species as prey items in only 2% (1/55) of sampled owls, highlighting the utility of molecular approaches for detecting diet items, especially degraded or visually absent items. Additionally, this approach has proven very useful in revealing cryptic trophic interactions in inaccessible seabird populations. For the most comprehensive analysis of diet, the use of both esophageal and cloacal swabs for metabarcoding is recommended. Supplementing metabarcoding with other methods that can provide complementary prey information, such as stable isotope analysis, would help to characterize trophic interactions more fully. The method described here has proven to be a reliable tool for investigating diet in invasive owls and may be used to investigate cryptic predation in living birds as a minimally invasive technique, as well.

Relationship between landscape structure and the diet of Common Barn-owl (Tyto alba) at different distances from the Drava River ecological corridor

Abstract This study investigated the relationship between landscape structure at different distances from the Drava River in South Hungary and the food composition of the Common Barn-owl. Pellets were collected from 15 villages between 2006 and 2008. Based on the CORINE land cover elements, five land use types were determined, and five landscape metrics were calculated to compare land use and landscape structure in the three distance zones. There were significant differences in the Shannon and Simpson diversity of small mammal assemblages between the three areas. A positive relationship was detected between the distance categories and the abundance distribution of the Striped Field Mouse and Field Vole. The relative abundance of the Striped Field Mouse in the diet of Common Barn-owl was influenced by the increase in the mean perimeter/area ratio and the mean of the contiguity index. The value of the trophic level index was negatively influenced by the decrease in crop patches and the increase in pasture and grassland areas, which land use types facilitate the distribution of insectivores. Our results suggest that landscape characteristics influence prey occurrence in hunting areas and the frequency-dependent availability of small mammal prey, which determines the resource utilization of Common Barn-owl.

Distribution of Four Vole Species through the Barn Owl Tyto alba Diet Spectrum: Pattern Responses to Environmental Gradients in Intensive Agroecosystems of Central Greece.

Voles are the most common vertebrate pests in European agriculture. Identifying their distribution and abundance patterns provides valuable information for future management. Barn Owl diet analysis is one of the optimum methods used to record small mammal distribution patterns on large spatial scales. From 2003 to 2005, a total of 10,065 Barn Owl pellets were collected and analyzed from 31 breeding sites in the largest agroecosystem in Greece, the Thessaly plains. A total of 29,061 prey items were identified, offering deep insight into small mammal distribution, specifically voles. Four discrete vole species (Harting's vole Microtus hartingi, East European vole Microtus levis, Thomas's pine vole Microtus thomasi, and Grey dwarf hamster Cricetulus migratorius) comprised 40.5% (11,770 vole prey items) of the total Barn Owl prey intake. The presence and abundance of the voles varied according to underlying environmental gradients, with soil texture and type playing a major role. M. levis showed no significant attachments to gradients, other than a mild increase in Mollisol soils. It was syntopic in all sites with M. hartingi, which was the dominant and most abundant small mammal species, preferring non-arable cultivated land, natural grasslands, set-aside fields, and fallow land. M. thomasi was strictly present in western Thessaly and strongly associated with a sandy-clay soil texture and Alfisol soils. C. migratorius was the least represented vole (162 items), exclusively present in eastern Thessaly and demonstrating a stronger association with cereals, Mollisol soils, and an argillaceous-clay soil texture. This is the first study in Greece at such a large spatial scale, offering insights for pest rodents' distribution in intensive agroecosystems and their response to environmental gradients including soil parameters.

Microplastic contamination in terrestrial ecosystems: A study using barn owl (Tyto alba) pellets

Microplastics (MPs) are recognised as an emerging environmental problem that needs to be carefully monitored. So far, MPs have been widely recorded in marine and freshwater ecosystems. Still, few studies have focused on MP occurrence in terrestrial ecosystems, although soils are suspected to be one of the main MP reservoirs. To test a non-invasive method for assessing MP contamination in terrestrial ecosystems, we analysed the pellets of a top terrestrial predator, the barn owl (Tyto alba). Sixty pellets were collected from three agricultural areas (20 pellets each) and analysed to assess both barn owl diet and MP content. Thirty-four MPs were confirmed by micro-Fourier Transform Infrared Spectroscopy (μ-FTIR) analysis in 33% of the pellets (min-max 1–5 MPs per pellet). Most of the detected items were microfibres (88.2%). Polyethylene terephthalate, polyacrylonitrile and polyamide were the most abundant polymers. One of the three sites was significantly less contaminated. In the two sites with the highest MP occurrences, barn owl diet was characterised by predation on synanthropic rodents, particularly brown rats (Rattus norvegicus), which may indicate habitat degradation and increased exposure to MPs. Analyses also suggest that Savi's pine vole (Microtus savii) is the prey least at risk of MP contamination, probably due to its strictly herbivorous diet. We argue that the analysis of barn owl pellets may represent a cost-effective method for monitoring MP contamination in terrestrial ecosystems.

Small mammals in the diet of Barn Owls (Tyto furcata) in an urban area in Rio de Janeiro state, Brazil, with a new record of the dwarf mouse opossum (Cryptonanus)

Abstract Several studies emphasize the use of owl pellets in small mammal inventories in natural areas harboring high richness of rare species, but few Brazilian Atlantic forest localities have been surveyed by this method. The present study documents the species composition and abundance of small mammals in the diet of Tyto furcata in an urban area of the municipality of Campos dos Goytacazes, Rio de Janeiro, Brazil, remarking on a new record of the dwarf mouse opossum genus Cryptonanus in the Atlantic forest. We analyzed 265 pellets regurgitated by a pair of T. furcata from November 2016 to September 2017 found in a nesting box. Analysis of the samples enabled finding a total of 596 individuals of four small mammal species. Mus musculus was predominant among the prey items (98.3%), while the native rodents Necromys lasiurus (1.3%) and Holochilus brasiliensis (0,17%) were much rarer. A single specimen of Cryptonanus sp. was identified among the diet items based on distinctive dental characters. The identification of this genus in the present study represents the second record in the state of Rio de Janeiro, and the sixth in the Atlantic Forest biome, suggesting that this marsupial occupies a wider ecological and biogeographic range. The present study underscores the relevance of owl pellets for small mammal surveys, even in urban and highly disturbed areas.

The diet of dingoes, feral cats and eastern barn owl on Pullen Pullen Reserve, southwest Queensland

Predator diet can provide important data to inform management actions as well as an enhanced understanding of the fauna of a region. The diet of dingo (Canis lupus dingo), feral cat (Felis catus) and eastern barn owl (Tyto delicatula) were compared using scat, stomach and pellets from a significant conservation reserve in southwest Queensland. Dingo diet was dominated by macropods, while the diet of feral cat and barn owl was dominated by small mammals. We found no remains of threatened species but recommend continued monitoring of predator diet as a tool to assist management.

Large-scale spatial patterns of small-mammal communities in the Mediterranean region revealed by Barn owl diet

Due to mainly opportunistic hunting behaviour of Barn owl can be its diet composition used for assessing local structure of small-mammal community. We evaluated the structure of small-mammal communities in the Mediterranean region by analysing Barn owl diet using own pellets and literature data (85 localities comprising 182,343 prey individuals). Contrary to widely accepted macroecological theory, we found a latitudinal increase of small-mammal alpha diversity, a less distinct west–east increase and lower diversity on islands. The mean prey weight decreased with increasing latitude, while on islands it decreased with increasing island area. The mean prey weight on islands was further negatively affected by mean land modification by human and positively affected by its range. The diet diversity on islands was not affected either by island area or its distance from the mainland. Its composition largely conformed to the main pattern pronounced over whole the region: an unexpected homogeneity of small-mammal community structure. Despite high beta diversity and large between-sample variation in species composition, Crocidura (+ Suncus etruscus) and murids (Apodemus, Mus, Rattus, in marginal regions partly replaced by gerbillids, Meriones or Microtus) composed more than 90% of owl prey in 92% of samples. Peak abundances of these widespread species are associated with a dynamic mosaic of dense patches of sparse herb vegetation and evergreen sclerophyllous shrublands interspersing areas of human activity, the dominant habitat of the inner Mediterranean and richest food resource for foraging Barn owls. The respective small-mammal species can be looked upon as invasive elements accompanying large scale human colonization of the region since the Neolithic and replacing original island biota. Our study documented that desertification of the Mediterranean played an important role in shaping inverse latitudinal gradient in diversity of small-mammals that contradicts to widely accepted mecroecological theory.

Barn owls as biological control agents: potential risks to non‐target rare and endangered species

AbstractRodent agricultural pests cause significant food loss every year. Attempts at mitigation via chemical pest control may cause secondary poisoning and harm non‐target species. Biological pest control by bolstering barn owl Tyto alba populations through the provision of artificial nest boxes is in use in several countries. The national biological pest control project of Israel began in the early 1980s in the Mediterranean zone and was subsequently expanded to the northwestern Negev desert, including areas adjacent to nature reserves and natural sand dunes, a threatened habitat in Israel. We analyzed prey of barn owls in the northwestern Negev to determine whether owls preyed on non‐target endemic, threatened rodents. A total of 14 632 prey items were collected from 95 nesting boxes between 2013 and 2016. We found that barn owls feed on protected and locally endangered species such as Gerbillus andersoni allenbyi (vulnerable − VU), Gerbillus pyramidum (VU), the endemic Meriones sacramenti (endangered) and Gerbillus gerbillus (critically endangered). These species constitute a significant proportion of barn owl diets (sometimes more than half of the prey items in a single nest box), especially in areas under 5 km from sand dunes, suggesting that bolstering the barn owl population may threaten locally endangered species. It could be hypothesized that agricultural crops serve as a resource for endangered species, allowing their numbers to increase, in which case their conservation status should be reassessed. However, extensive rodent trappings in agricultural fields in the region revealed <1% Gerbillus individuals, while in nearby dunes only gerbils were trapped. Insufficient data are available to assess whether or not M. sacramenti could have become a local pest. Our study highlights the risks that may be associated with the use of barn owls as rodent control agents in areas where natural open landscapes and nature reserves are interspersed with agricultural landscapes.

Global biogeographical patterns in the diet of a cosmopolitan avian predator

AbstractAimThe investigation of biogeographical patterns in the diet of widely distributed predators is essential to understand their ecology, life history traits and local adaptations. However, it is particularly challenging because of their wide distribution, broad trophic spectra and high ecological plasticity. Here, we described patterns of trophic ecology in a cosmopolitan nocturnal raptor, the common barn owl group, from a biogeographical perspective. We then compared variation in diet between barn owls living in the Americas (T. furcata), and those inhabiting Europe, Middle‐East and Africa (T. alba), thus hunting on different assemblages of prey types.LocationWorld.TaxonBarn owl species complex.MethodsWe reviewed 790 studies reporting diet information of 971 locations (3,733,902 individual vertebrate prey), and investigated the variation in different diet parameters, reflecting taxonomic diversity, size of the prey and frequency of certain prey types according to geographical and climatic variables.ResultsWhile confirming that the barn owl is a selective mammal hunter with variable taxa constituting its staple food in different regions, we also found significant geographical and climatic trends in several diet parameters. Although prey composition differed among continents, most of the patterns, including an increase in proportion of mammal prey in cold environments, an increase in diet diversity with elevation, a decrease in small prey consumption from high to low latitudes and at increasing temperature, and a decrease in rodent predation in humid habitats, were similar between T. furcata and T. alba. A strong island effect was observed for all diet parameters.Main conclusionOur results indicate a generalized pattern of variation in barn owl diet across biogeographical regions, suggesting that similar prey communities occur in habitats with comparable ecological conditions and/or that different barn owl populations living in similar climate convergently evolved similar food preferences and hunting strategies.

Diet composition of introduced barn owls (Tyto alba javanica) in urban area in comparison with agriculture settings

AbstractThis study investigated the diet of introduced barn owls (Tyto alba javanica, Gmelin) in the urban area of the Main Campus of Universiti Sains Malaysia, Penang, Malaysia, based on collected regurgitated pellets. We also compared the diet of the introduced barn owls with the diet of barn owls from two agricultural areas, i.e. oil palm plantations and rice fields. Pellet analysis of introduced barn owls showed that commensal Norway rats, Rattus norvegicus, made up the highest proportion of the diet (65.37% prey biomass) while common shrews, Suncus murinus were the second highest consumed prey (30.12% prey biomass). Common plantain squirrel, Callosciurus notatus, made up 4.45% of the diet while insects were taken in a relatively small amount (0.046% prey biomass). Introduced barn owls showed a preference for medium-sized prey, i.e. 40–120 g (52.96% biomass and 38.71% total). In agricultural areas, rice field rats, Rattus argentiventer predominated the diet of barn owls (98.24% prey biomass) in rice fields while Malayan wood rats, Rattus tiomanicus, were the most consumed prey in oil palm plantations (99.5% prey biomass). Food niche breadth value was highest for barn owls introduced in an urban area with a value of 2.90, and 1.06 in rice fields and 1.22 in oil palm plantations. Our analysis reiterates the prey preference of barn owls in various landscapes for small mammals. Our results also indicate the suitability of utilizing barn owls as a biological control not only in agricultural areas, but also as a biological control agent for commensal rodent pests in urban areas.

Indirect commensalism between an introduced apex predator and a native avian predator

In ecosystems, some organisms facilitate others indirectly, by interacting with one or more common mediator organisms. Thus, the indirect effects of introducing or removing species can be resonant, sometimes leading to successional extinctions. The dingo (Canis dingo) is the apex predator in Australian deserts and was introduced to the continent between 3000 and 5000 years ago. Dingoes suppress the abundances of introduced mesopredators, the red fox (Vulpes vulpes) and feral cat (Felis catus) and in so doing mitigate small mammal declines wreaked by these mesopredators. Given the positive association between the abundances of dingoes and small mammals, we predicted that dingoes indirectly facilitate a specialised native predator of small mammals, the Barn owl, Tyto alba. We tested our prediction by monitoring the abundances of dingoes, foxes, cats, small mammals and barn owls and investigating barn owl diets in areas where dingoes were common versus areas where dingoes were functionally extinct on either side of the dingo barrier fence (DBF) in the Strzelecki Desert. Foxes and cats were less abundant in areas where dingoes were common. Conversely, small mammals and barn owls were more abundant where dingoes were common. Owls in areas where dingoes were common fed almost exclusively on small mammals, but owls in areas where dingoes were functionally extinct fed on greater proportion of birds and invertebrates. The findings of our study provide evidence that an introduced apex predator may indirectly facilitate a native predator and illustrates the myriad of far-reaching indirect effects that can result from apex predator suppression.

Long-term human-induced landscape changes and small mammal communities in a Mediterranean place

The small mammal community (Orders Rodentia and Eulipotyphla) was evaluated in one single locality in coastal Catalonia in relation to human-induced changes in land use. Low detectability of some species drove us to assess the small mammal assemblages analysing barn owl (Tyto alba) pellets sampled in the same nesting site for a period of thirty years. The objectives were to 1) describe variations in landscape use, 2) document small mammal community changes and 3) relate these changes to those in land use. Species richness did not seem to vary with changes in land use, however, when species were separated into guilds (open, forest and synanthropic), significant differences could be observed. The open guild decreased by 6%, while the forest and synanthropic guild increased by 5% and 2% respectively. Abandonment of arable land, expansion of forested areas and an increase in urbanisation were closely linked to these guild changes, while some individual species showed variations which paralleled climatic changes. Loss of adequate open habitat for this raptor was highlighted by a species substitution, with the tawny owl (Strix aluco) occupying the nesting site previously used by the barn owl during the last years of the study. Barn owl diet monitoring therefore proves to be a useful tool to analyse small mammal community responses to changes in the environment, allowing for more specific and viable conservation plans for both small mammals and barn owls.

A contribution to the knowledge of diet composition of the Barn Owl Tyto alba in the area of Pisa (Italy)

Abstract We examined the pellets of the Barn Owl Tyto alba, collected in Pisa, Italy, in 2012. Altogether, 219 specimens of small mammals were found in 85 pellets. The Barn Owl diet was composed of ten species of small mammals, representing three different families (Muridae, Cricetidae, Soricidae). The main prey species was the Wood Mouse Apodemus sylvaticus, followed by the House Mouse Mus musculus and the Savi’s Pine Vole Microtus savii. While the smallest of the small mammals from the area, the Etruscan Shrew Suncus etruscus, was well represented in the pellets, some larger species of small mammals were not represented at all. The reason for such result may lie in the upper limit for our Barn Owl’s prey size. Results suggest that optimal prey weight for our Barn Owl may be between 26–75 g of body mass, however, the prey can be occasionally as heavy as almost 100 g, represented by adult Rat Rattus spp. Nevertheless, our results may not reflect the true hunting strategy of the Barn Owl, but the availability of a certain food item at one point in time.

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

BackgroundThe barn owl, a nocturnal raptor with cosmopolitan distribution, shows a great adaptability to different environments. Regarding prey, the barn owl is a rather selective species, but if changes in the abundance of the selected prey occur, it becomes an opportunistic predator and easily incorporates other prey in its diet, using a wide range of prey species and foraging habitats. Small rodents are usually the prey mostly used. Compared to the populations of north and eastern Europe, barn owl populations in the Mediterranean area have been the least studied. In Cyprus, where barn owl is a common bird species, there are no studies on its diet and feeding ecology. This study was carried out to contribute to the spatial and temporal patterns barn owl diet in Cyprus also providing information on small mammals’ presence and species composition on the island.MethodsThis study was based on 1407 regurgitated pellet analysis that were collected from 26 sites representing six major habitat types on central and southern Cyprus from summer 2013 to summer 2014. The diet of the barn owl was described in terms of seasonal average biomass and numerical percentages of each prey species and compared by Kruskal–Wallis test. Seasonal prey diversity and evenness indices were also calculated. Principal component analysis (PCA) was performed on the prey biomass proportion data assigned to six major habitat types with regard to elevation, vegetation and human uses.ResultsLow prey diversity was found comprised mainly of rodents (overall means 96.2 and 95.7% by number and biomass, respectively). Mice followed by rats were most important prey whereas insectivores, birds and insects were minor components of the owl’s diet. Evenness and diversity values were relatively similar among seasons. PCA differentiated mainly between lowland areas where mice were more abundant prey and mountainous areas where rats dominated in the diet. Insectivores correlated with birds, prey types characterizing several lowland and highland habitats.ConclusionsThe barn owl prey composition in Cyprus suggests an opportunistic foraging behavior, low prey species diversity with variations in the main rodent prey that could be explained by their distribution, seasonal activity and habitat preferences.

Dominance of Invasive Small Mammals in the diet of the Barn Owl <em>Tyto Alba</em> in County Cork, Ireland

Dominance of Invasive Small Mammals in the diet of the Barn Owl <em>Tyto Alba</em> in County Cork, Ireland

Barn Owl (Tyto alba) Diet Composition on Intensively Used Agricultural Land in the Danube Lowland

Based on pellets analysis from five localities in south western Slovakia (Malá Mužla, Malé Ripňany, Obid, Opatovský Sokolec and Tešedíkovo), we studied the diet composition of Barn Owl (Tyto alba) in intensively cultivated agricultural lands. A total of 6218 specimens of prey, 17 mammalian and 7 bird species were identified. The main prey species found in all food samples was the Common Vole (Microtus arvalis), varying between 56 % and 67 %. The proportion of synanthropic species (Rattus norvegicus, Passer domesticus) and species inhabiting agricultural landscapes (Crocidura leucodon, Crocidura suaveolens, Mus sp.) increases in localities with a lower ratio of the Common Vole. The results suggest land use affects the diet of Barn Owls, confirming conclusions which have been drawn in previous studies. From faunistic point of view, discovering the Pannonian Root Vole (Microtus oeconomus mehelyi) in the diet from Malá Mužla was important.