Diet Of Owls 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.

Invertebrate-biased diet of burrowing owls in a newly-restored coastal grassland

Recovering biodiversity across trophic levels is a major challenge in restoration ecology. Specifically, predator population recovery depends on the timely re-establishment of their preferred prey species in restored habitats. Here, we evaluate potential dietary factors contributing to the loss of western burrowing owls (Athene cunicularia hypugaea (Bonaparte, 1825)) from a newly-restored coastal grassland. We examined owl pellets and found that burrowing owl diets were relatively low in vertebrate prey during their brief occupation of the restoration site (2.6% of prey items; found in 61.8% of sampled pellets). We suggest that preferred food limitation may have been one contributor to the loss of owls from the restoration site. These findings suggest the need to prioritise re-establishment of prey communities for effective long-term recovery of burrowing owls in restored landscapes.

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.

Trophic diet of the Long-eared owl Asio otus (Linnaeus, 1758) (Aves, Strigidae) in the Daya d'El-Gouffa (Laghouat, Algeria)

This research aims to study the trophic diet ofthe long-eared owl Asiootus and based on the examination of 120 regurgitation pellets of this raptor. These pellets were collected during the period from August to november 2020, near the Dayad'El-Gouffa located in the region of Laghouat. The analysis of the 120 pellets revealed a total of 273 individuals divided into 39 species belonging to four zoological classes. The consumption of small mammals, mainly Rodentia-Gerbillidae, is very common in arid environments. These constitute the basis of the diet of this raptor. Of the four families of rodents consumed, the Gerbillidae family is the most dominant one. It clearly stands out from the other families with a very high rate of 92.5% of the total rodents consumed. The Dipodidae are the least consumed (4.8%). In terms of species, Pachyuromusduprasi is the most dominant species with 31.5%. The values of the Shannon-Weaver index seem to be high. The highest one is recorded in november with 4.2 bits against 3.1 bits recorded in august. The calculated equitability values tend towards one for all four months of the study, so the numbers of the different components of the long-eared owl diet tend to be in balance with one another. This implies that Asiootus behaves as a generalist opportunistic predator.

Perceptions, Knowledge, and Emotions About Owls in Southern Ecuador

Owls hold significant utilitarian and aesthetic values for humans, ranging from pest control to ecotourism. However, cultural beliefs rooted in negative perceptions and emotions have led to conflicts and threats to many owl species. In South America, research on the relationship between owls and people is limited. This study aims to identify the variables involved in the construction of social knowledge, perceptions, and emotions toward owls. Face-to-face questionnaires were administered to residents in southern Ecuador. The data were analyzed using decision trees, a novel approach in ethnobiology. The results indicate that participants exhibited accurate knowledge of owl diet and habitat, with a majority having previous owl sightings and familiarity with their vocalizations. These factors, along with the sources informing their knowledge (such as school and family), contribute to the development of neutral perceptions and emotions toward these birds. The majority of participants recognize the importance of owls for the environment and support their conservation, with these two variables playing a crucial role in shaping positive emotions. Additionally, perceptions and emotions are primarily influenced by the region of residence. The presented data provide valuable insights into the significance of social perceptions and emotions in designing strategies to mitigate intentional owl mortality and persecution resulting from misconceptions and misperceptions.

Food habits of the endemic Cyprus scops owl (Otus cyprius) during the breeding season

Abstract The diet of the endemic Cyprus scops owl (Otus cyprius) was studied for the first time during the breeding season 2021 in 7 nesting sites from 6 sampling locations using the pellet analysis (n = 65 pellets). Insects, mostly Orthoptera and Coleoptera, comprised the bulk of the owl diet (87% abundance, 31% biomass), whereas small mammals and reptiles were important in terms of biomass, with 41% and 24%, respectively. Birds were the lowest prey order, with 0.6% abundance and 3.6% biomass. The most essential insects were grasshoppers (Acrididae) (17%) and scarab beetles (Scarabaeidae) (6%). From vertebrate prey, Mus spp. (23.7%), Mediterranean house gecko (Hemidactylus turcicus) (8%), Cyprus spiny mice (Acomys nesiotes) (8%), juvenile black rats (Rattus rattus) (7%), and Cyprus agamas (Laudakia cypriaca) (5%) stand out as % biomass. Predation on a bat species (Pipistrellus sp.) by scops owl was documented for the first time in Cyprus. The estimated prey biomass ranged from 0.1 – 25 grams, averaging 2.1 g.

Rozšíření myšivky horské (Sicista betulina) v Pošumaví na základě rozboru potravy sov (Rodentia: Zapodidae)

Distribution of Sicista betulina in the Šumava Mts. (Bohemian Forest, SW Bohemia, Czech Republic) based on owl diet analysis (Rodentia: Zapodidae). The Šumava Mountains are one of the three areas of a relict occurrence of the northern birch mouse (Sicista betulina) in the Czech Republic. The present study summarises all records of this species obtained there by the analysis of diet of three species of owls, the Tengmalm’s owl (Aegolius funereus), to a lesser extent of the Ural owl (Strix uralensis) and tawny owl (Strix aluco). A total of 355 sample sets from 228 localities was processed, positive findings concern 57 localities where the northern birch mouse was found (322 individuals). The presence of the species was confirmed in an area of approximately 1,400 km2, which corresponds to 13 mapping fields of the KFME, four of which extend into the territories of Germany and Austria (field numbers 7047, 7148, 7249, 7350). More than a third of the localities (37.0%) and nearly two thirds of the individuals (62.4%) come from four mapping fields (7048, 7049, 7148, 7149) covering mainly a peaty alluvial plain of the upper stream of the Vltava river and its surroundings. Data obtained by observation or capturing of the northern birch mouse give a similar picture. Thus, this territory with the high proportion of relict vegetation can be considered as the core area of the current occurrence of the mouse in the Šumava Mts. The altitude range of the northern birch mouse records from owl pellets is 680–1160 m a. s. l. with a mean of 871.7 m a. s. l. Almost a third of the localities (32.0%) lie in the altitudinal range of 700–800 m a. s. l., and more than four fifths of the records (82.7%) fall within the range of 700–1000 m a. s. l. However, these are only indicative values that can be influenced by the size of the individual hunting territories of owls (especially in a landscape with a steep mountainous relief). Our results confirm the previously described zoogeographical profile of the northern birch mouse in the Šumava Mts., i.e., that its distribution is limited only to the south-eastern half of this mountain range and ends roughly in the Kvildské pláně region in the north-west. Records of the northern birch mouse on the Bavarian side of the mountain range are in full agreement with this. It can be assumed that the species occurrence in the whole Bohemian Forest is primarily shaped by its Holocene history. Furthermore, it has been confirmed that the analysis of the diet composition of the Tengmalm’s owl is an effective method of study of the geographical distribution of the northern birch mouse.

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.

First documentation of acorn consumption by eastern screech owl (Megascops asio)

We present evidence for the first documentation of consumption of a water oak (Quercus nigra) acorn by an eastern screech owl (Megascops asio). A screech owl diet typically consists of small mammals, small birds, and arthropods. In our study, we had a 1-m x 1-m sand pad under observation from a game camera that was set on a 1-min time-lapse delay. On this sand pad, we placed five water oak acorns. In a series of six images over six minutes, we observed an eastern screech owl land near the sand pad, walk to an acorn, and appear to consume the acorn. Although there could be other plausible explanations and events that transpired between 1-min image intervals, we believe this acorn was consumed by the eastern screech owl. The importance of this addition of food type to the diet of a raptor is largely unexplored and undocumented.

Intraguild Predation by Eurasian Eagle-Owl Bubo bubo on Booted Eagle Aquila pennata and Long-Legged Buzzard Buteo rufinus

In August 2018 remains of several birds of prey were recorded at one Eagle Owl Bubo bubo eyrie in southeast Romania. Among these, still articulated wings and leg bones of an adult female Booted Eagle Aquila pennata, feathers and several bone fragments of one adult Long-legged Buzzard Buteo rufinus and several individuals of Common Buzzards Buteo buteo were identified. While predation of Eagle Owls on different raptor species is well known, booted Eagles and Long-legged Buzzards are rarely preyed upon. Based on changes that occurred in the overall diet of owls at this particular eyrie, it is hypothesized that a shortage in the main prey species (induced by land use changes in the region) may be the cause of these extraordinary predation events. While predation of Eagle Owls on large diurnal raptors is more an exception than a norm, in areas where threatened diurnal raptors breed, the presence of Eagle Owls may cause conservation concerns/prove to be problematic.

A Kist o’ Whistles

A Kist o’ Whistles

Mammals in Tawny Owl (Strixaluco) pellets from Kharkiv Region, Ukraine.

The Tawny owl (Strixaluco) is a common owl species in Europe, demonstrating generalist diet strategy. Its main prey are small rodents and numerous studies show that the composition of its diet broadly reflects changes in prey species abundance in its habitats. Due to strictly sedentary habits of adult birds and their year-round territoriality, it is possible to locate habitats of their prey with a precision of several hundred metres. Analysis of owl pellets is a traditional method in faunistic studies to provide data on distribution of small mammals, especially cryptic species which are hard to be found using trapping. Here, we present a dataset on mammals found in Tawny owl pellets collected during up to 13-year studies in the Kharkiv Region, Ukraine in three territories. Data from two territories were collected in a systematic way and allowed us to make analysis of seasonal, year-to-year and habitat variability in the Tawny owl diet and local mammal species composition.

Dormice (Gliridae) in the Diets of Predators in Europe: A Review Broadening Understanding of Dormouse Ecology

This study aimed to evaluate the significance of dormice in the diets of predators in Europe and, as a result, expand the knowledge about dormouse ecology. A total of 535 sources containing information on dormice in the diets of predators were analysed. Countries of Southern and Central Europe stand out with the largest numbers of target sources. Dormice were recorded in the diets of 54 predator species: 23 mammals, 11 owls, 16 diurnal birds and 4 reptiles. Owls hunting in forests, particularly the tawny owl Strix aluco, are the main dormouse predators. The role of dormice in the diets of predators depends on dormouse abundance, and the highest proportion was recorded in the Mediterranean region, where edible dormice Glis glis are abundant. In particular periods, dormice may be an alternative prey for owls and some other predators. Dormice were seldom recorded in the winter diets of predators, especially in mammals, contrary to what was previously thought. Records of dormice in the winter diets of owls confirm that dormice leave their hibernacula during arousals in the thaw periods. The presence of dormice in the diets of diurnal birds suggests that nocturnal dormice may also be active in the daytime.

Monitoring of the mammal fauna by studying owl pellets: a case of small mammals in protected areas of Podillia

Using owl pellets analysis to monitor mammals in protected areas makes it possible to accumulate a unique material to study the distribution and relative abundance of both common and rare species. Due to the ease of collecting and accumulating of pellets, this method helps to quickly obtain a large amount of material to monitor the changes in natural areas and objects during certain time intervals without interfering with the course of natural processes. The proportions of small-mammal species in the diet of most owls are representative of the proportions of species in their groups. Therefore, the pellet method can be used to organise monitoring of mammal species of natural regions. We analysed nearly 2000 pellets of several species of owls collected in Podillia in the course of the study. Pellets are mostly collected within protected areas. Small mammals form the basis of the diet of the studied species of owls. The diet of the short-eared owl is the most diverse, and it includes 18 species of small mammals. The common vole occurs the most often. The diet of other owl species is also diverse, in particular of the little owl, tawny owl, and eagle owl. As in the case of the short-eared owl, the main prey of the barn owl and grey owl is a common species—the common vole. The diet of the eagle owl, unlike others, is dominated by larger small-mammal species—brown rat, white-breasted hedgehog, and European hamster. In addition to common species, the analysis of owl pellets allows us to identify not only the most common, but also rare species, such as the European hamster, bicoloured shrew, lesser white-toothed shrew, and various bats. Therefore, the pellet method of research is highly effective in analysing the composition of the fauna and the structure of communities, of both prey and predator species. Owl pellet analysis is a valuable asset during small-mammal monitoring studies, and is especially useful for sampling of indicator small-mammal species during environmental impact assessments in protected areas. The method has considerable advantages compared to standard survey methods of small mammals— it does not require the removal of animals from the natural environment, which makes it relevant for use in protected areas.

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.

Breeding Parameters of an Introduced Barn Owl (Tyto alba javanica) Population in an Agricultural Area

ABSTRACT As part of a biological control program against rat (Rattus spp.) populations in oil palm plantations, Barn Owls (Tyto alba javanica) were translocated from Peninsular Malaysia and released in an oil palm plantation in Lahad Datu, Sabah, Malaysia, on the island of Borneo. We installed 16 nest boxes every 25 ha at the study site and monitored those nest boxes monthly from June 2014 to June 2018 to assess Barn Owl breeding parameters. We collected regurgitated pellets from nest boxes to analyze the prey of the owls. Average nest box occupancy rate throughout the entire study period was 66.7% (±6.1). Nest box occupancy was lower in the first year of the study (average occupancy rate 23% ± 3.6) but increased significantly in the following years. We recorded 84 successful breeding attempts and a total of 555 eggs throughout the study period; 61% of eggs hatched and 60% of eggs produced young that successfully fledged. Clutch size per laying pair ranged from 1 to 9 (average = 5.6) and the brood size at fledging ranged from 1 to 7 (average = 4.0). Diet of the Barn Owls consisted of only small mammals; rodents made up 99% of analyzed pellets, and shrews accounted for 1%. There has been no previous record of Barn Owls naturally occurring in Borneo and this is the first breeding population successfully translocated and established.

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.

DNA metabarcoding reveals the threat of rapidly expanding barred owl populations to native wildlife in western North America

Invasive predators can have detrimental impacts on native species and biological communities through direct consumptive effects and indirect effects on trophic interactions, yet these relations are often poorly understood through the initial stages of predator expansion. Leveraging early, lethal collection efforts to study invasive barred owls (Strix varia) at the leading edge of their range expansion in northeastern California, we conducted DNA metabarcoding of intestinal samples to assess the diet of this invasive predator. Through the development of customized primers and this novel approach to observing owl diet, we screened the intestinal contents of 124 barred owls and detected a broad diet of 78 unique prey types (48 vertebrates and 30 invertebrates), including prey types undetected in previous methodologies. Mammals were the most consumed vertebrate class (frequency of occurrence = 65 %), followed by amphibians (32 %), birds (22 %), and reptiles (19 %). Diets differed regionally but were similar among ages and sexes and exhibited limited variation in response to local environmental conditions. Our work highlights the generalist predatory strategy of invasive barred owls, identifies numerous native species potentially threatened by their range expansion, and indicates that they will not serve as ecological replacements for congeneric spotted owls (Strix occidentalis) they displace. These findings suggest that expanding currently limited barred owl removals could benefit native species and communities in western North America. More broadly, we demonstrate DNA metabarcoding, combined with early intervention, provides a powerful tool for conducting detailed assessments of species consumed by invasive predators, potentially incentivizing conservation actions and improving outcomes.

Unconventional bird predators are relevant to vertebrate trophic relationships? A community science platform helps to answer this question.

Birds stand out among animal predators due their high species diversity and ecological flexibility. In a restrictive sense, bird predators include species that had vertebrate meat as main food item (conventional bird predators). However, insectivores, frugivores and omnivores birds occasionally include vertebrates in their diets (unconventional bird predators). Here, we use photographs posted in a community science platform (wikiaves) to examine the importance of conventional and unconventional bird predators to the trophic structure of Neotropical vertebrate assemblages. After detailed inspection of 71,285 photographs, we built a database of 6553 feeding events from 640 species distributed in 32 bird families. Vertebrates are part of the diet of 92 species of conventional and 91 species of unconventional bird predators. As expected, diets of conventional bird predators are predominantly composed of vertebrates (84% of feeding records, n = 1689), although invertebrates were also relevant for diets of owls, hawks and herons. In contrast, vertebrates comprised only 8% of feeding records (n = 358) among the unconventional bird predators. The contribution of vertebrates to diets of unconventional bird predators was relevant (> 10% of feeding records) in five of 24 analyzed bird families. Fishes, mammals and birds are the main preys of conventional predators, whereas unconventional predators focusing on ectothermic vertebrates (amphibians and reptiles). Unconventional predators expand the diversity of local vertebrate predators and consume distinct preys compared to conventional predators. Therefore, families of unconventional bird predators must be considered relevant to food web analysis of Neotropical vertebrate assemblages.