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The diet of a single Maghreb Owl Strix mauritanica (family Strigidae) was examined within its natural habitat at Kahf Lakhal cave on Jbel Moussa, a mountain in northern Morocco. The two distinct batches of pellets collected contained a total of 190 prey items. Pellet analysis revealed a diet comprised of four primary taxonomic classes of prey: mammals, insects, birds and reptiles. We identified 29 prey species, representing 21 families. Mammals were the most prominent component, accounting for 49.5% of the diet items and included at least nine distinct species. Insects constituted 28.9% of the diet, representing at least eight species; birds comprised 20%, representing at least 11 species; and reptiles were represented by a single species (3.4%). Numerically, the most frequently captured prey species were the common bent-wing bat Miniopterus schreibersii (22.1%), black rat Rattus rattus (8.4%) and European rhinoceros beetle Oryctes nasicornis (7.9%). In biomass, black rats were the biggest component of the owl's diet (31.8%), followed by Barbary Partridges Alectoris barbara and hares Lepus sp. (each 11.9%); together these three species comprised more than half the estimated biomass of the prey types consumed by the owl. This investigation significantly improves our knowledge of the diet of the Maghreb Owl in the North African region. [ABSTRACT FROM AUTHOR]

The Lesser Kestrel Falco naumanni is a small migratory falcon, foraging in areas covered by relatively low vegetation. In the Thessalian Plain, Central Greece, it feeds mainly on large Orthoptera and Coleoptera, and is characterized by an opportunistic feeding strategy. The purpose of this study was to investigate the composition of the Lesser Kestrel diet in the Thessalian plain. Systematic visits to two large representative colonies of the Lesser Kestrel in the study area were performed, in order to collect pellets during 2014 and 2015 breeding and post breeding periods of the species. Pellet analysis indicated that Orthoptera and Coleoptera were the main prey categories, which seem to have been the most specialized and dominant feeding choices of the species in the study area, while all other prey categories were rare and not specialized. Lesser Kestrel relied its diet on Orthoptera (Tettigoniidae and Acrididae), mainly during the breeding and post breeding phases, while the feeding strategy of the species during these two phases can be characterized as opportunistic. On the contrary, prior to the breeding phase, main prey category of the species in the study area was Coleoptera (Carabidae and Scarabaeidae). Moreover, a narrower niche breadth of the species based on Levins' index, was recorded during the breeding phase for both years of the study, indicating that the species restricted the variety of the diet during this phase. Conclusively, the species during its whole breeding season made different prey choices, depending on the breeding phase and its specialized needs during each phase. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Bio-waste is a source of energy-rich material. Therefore, it can be used in further processes and efficiently utilized. Further processes of waste utilization include compressing them to pellets. However, this type of pellet often has a low bulk density, high ash content, low ash melting temperature, and low calorific value. This research dealt with the energy properties of peanut and pistachio nut shells that were pure or mixed with spruce sawdust in half proportion and compressed into pellets. As a continuation of previous research, the properties of these pellets prepared were measured and compared with pure spruce pellets and with pellets from walnut shells. The tested shell pellets had calorific values similar to wood pellets from spruce. However, mixing nut shells with spruce solved the problems of high ash content and low ash melting temperatures. The amount of wood present in the pellets resulted in increased ash melting temperatures and decreased the ash content. [ABSTRACT FROM AUTHOR]

As an opportunistic predator, the Common Barn-owl (Tyto alba) proved to be an appropriate model organism to survey the composition of small mammal assemblages. This study analysed barn owls’ pellet samples from 14 localities containing 34 animal taxa and 4,088 prey items in two years (2015–2016). Two groups of samples (7–7 localities) were separated based on the dominance of semi-natural habitats and agricultural lands. Rarefaction analysis proved that the species richness and diversity of barn owls’ diet were significantly higher in semi-natural landscapes. The multiple regression analysis between PCA scores showed that in the agrarian landscape the abundance of generalist species was influenced by the proportion of forests, while the value of the trophic level index was determined by the size of arable fields. In the case of semi-natural landscapes, the abundance of the synantrop guild and generalist species, especially S. araneus and A. agrarius, was influenced by the proportion of urban areas, the number of habitats and the size of arable fields. The results of this study suggested that the small mammal consumption of the Common Barnowl is significantly different in the two landscapes, which reflects the impact of habitat heterogeneity and agricultural activity on prey availability. [ABSTRACT FROM AUTHOR]

Various waste materials have energy potential. It is important to make use of this potential and prepare the product for further use by treating the waste. Treatments such as compressing waste into pellets leads to increasing the energy density of this fuel, which benefits transport and storage costs. However, low bulk density, high ash content, low-ash melting temperatures, and low calorific values of non-woody pellets can cause problems during their combustion. This article deals with the energy usage of walnut shells, which were blended with spruce sawdust in various amounts and compressed into pellets. The mechanical and energy properties of these were measured and compared with recommended or standardized values. The formed pellets met the quality limit for bulk density, ash content, moisture content, the content of nitrogen and sulfur, and net calorific value according to ISO 17225. However, low ash melting temperatures were noticed for pellets from pure walnut shells, and also lower mechanical durability for produced pellets with walnut shells contents higher than 10% were detected. [ABSTRACT FROM AUTHOR]

We investigated temporal changes in diet composition of the Montagu's Harrier Circus pygargus breeding in natural habitat (calcareous peat bog) in SE Poland. We characterized diet composition in a three‐year period (2007–2009), based on pellet analyses. We investigated whether diet composition was affected by years or stage of breeding. We compared diet of the studied population between 2000s and 1990s and with other populations. We found that the food of the studied population was dominated by insects and mammals (by number) and mammals and birds (by biomass). Biomass and abundance of main prey items differed between studied years because of different air temperatures. We found some interannual differences in contribution of some prey items including higher number of thermophilic prey (insects and amphibians) in warmer years. Comparison of pellet composition in the 1990s and 2000s revealed significant increase in the abundance of thermophilic prey (insects and reptiles) and decrease of mammals including Microtus voles and birds. Those changes may be linked to habitat changes in areas neighboring peat bogs and climate change‐induced changes in prey communities. The studied population was able to respond to changes in foraging habitats and prey composition by opportunistic foraging on easily available prey. The diet of the studied population is the most similar to the geographically closest populations foraging in similar habitats and characterized by high contribution of insects. [ABSTRACT FROM AUTHOR]

In this study, we analysed a total of 691 pellets of the Long-eared Owl (Asio otus L.) collected from Edirne (Suburban), İstanbul (Suburban) and Kars (High altitude steppe) provinces in January-February 2019. Dietary contents of the Long-eared Owl were considering the different habitat (steppe and suburban) types. Small mammals constituted the majority of the diet content in all areas, but a small amount of bird remains were also found in pellets. 1474 prey items belonging to 7 different mammal taxa (Apodemus sp., Cricetulus sp., Crocidura sp., Micromys sp., Microtus sp., Mus sp., Rattus sp.) were identified. High amount of Mus sp. was found in pellets collected from Edirne (50.34%) and İstanbul (41.42%). On the other hand, Microtus sp. was the main prey species in Kars. Overall, our study supported that the Long-eared Owl acts as an opportunistic predator and change its dietary contents according to different environmental conditions. Incompatible results were obtained between the trapping study and pellet examination. The reasons could be that some mammal species can be caught by chance, trapping area cannot represent the entire hunting area and some mammal species could avoid trapping. [ABSTRACT FROM AUTHOR]

The present paper builds on older published studies of diet of the Eurasian Eagle-owl (Bubo bubo) at traditionally used nest sites in the Česká Lípa region (northern Bohemia), which provided an opportunity to analyse changes in the composition of food brought to the nests over a period of approximately 80 years. Substantial changes were recorded predominantly in species that gradually disappeared from the landscape after 1940. Progressively, the proportion of game species (Grey Partridge, Perdix perdix, Common Pheasant, Phasianus colchicus, European Hare, Lepus europaeus) and species dependent on a heterogeneous and extensively grazed farmland (European Hamster, Cricetus cricetus) decreased in the diet. At the same time, the number of species associated with intensive farming (Brown Rat, Rattus norvegicus) increased in the diet. Changes in the composition of food probably reflect the changes in the agricultural, forestry and hunting land use and their consequences in the composition of zoocenoses in which the Eurasian Eagle-owl obtains its food. [ABSTRACT FROM AUTHOR]

Little is known about the foraging ecology and breeding biology of the Stygian Owl (Asio stygius robustus) across Central America. We located one Stygian Owl roost site in the Mountain Pine Ridge Forest Reserve in the Cayo District of Belize, where we collected pellets over a one-year period (n = 145; Mar 2009–Feb 2010). All identified prey items (n = 194) were passerines (69%), bats (19%), or beetles (12%). We used a proportions test and found seasonal variation in diet, with increased passerine prey consumed in the dry season (Jan–May) and increased beetle prey consumed in the wet season (Jun–Dec). This shift in diet may be influenced by temporal variation of passerine abundance and the emergence of beetles at the start of the wet season. In December 2010, we affixed an adult male Stygian Owl with a VHF transmitter, recorded regular movements using triangulation, and located an occupied nest with a single nestling in sub-montane pine forest habitat. The tagged male had a home range of 36 km2 and was documented regularly flying up to 16 km from the nest site through broad-leaved forest to hunt in agricultural habitat, while roosting and nesting only in sub-montane pine forest. The use of human-created habitats, such as agriculture, could unveil threats not previously of concern for this species (e.g., pesticide use). Our findings further our knowledge on seasonal diet for Stygian Owls and highlight distinct habitat usage for both roosting and foraging, which has important conservation implications for an understudied Neotropical owl. [ABSTRACT FROM AUTHOR]

The decline of the White Stork (Ciconia ciconia) in the Iberian Peninsula was averted within the last 30 years, partially due to an increase in food availability in landfills. In this study, we compared 2 colonies located at different distances from a landfill in southern Portugal, with the aim of assessing differences in stork diets. We also compared our current results with data from the same colonies before the landfill was built. Additionally, we studied storks' exposure to kleptoparasitism by Black Kites (Milvus migrans) as a potential factor affecting their feeding behavior in landfills. We analyzed 182 pellets collected in 2005 and 2010 in non-landfill colonies and from landfills only in 2010. We carried out >47 h of focal observations of storks feeding at the landfill. Pellet contents are primarily insects (15 families from 5 orders) as well as unidentified and inorganic materials. Our analyses of variance revealed significant local, seasonal, and annual differences in Coleoptera, Orthoptera, Hymenoptera, and total number of insects. Our observations at the landfill showed that storks feed on large amounts of organic material, mostly fresh meat and fish, which means that observational data differs from pellet data. Black Kites kleptoparasitize White Storks mainly at the beginning and end of the morning limiting their food intake and increasing the amount of time storks spend at the landfill. We conclude that foraging in landfills has provoked an important shift in the White Stork's diet, partially replacing these birds' natural food items and exposing them to potential new threats such as the ingestion of inorganic material and exposure to kleptoparasitism by kites. [ABSTRACT FROM AUTHOR]

Scavenging is an important ecological function that increases individual fitness and transfers energy between trophic levels. Scavenging by owls has been documented opportunistically through direct observations, camera trapping, and pellet analyses, but it is unknown how frequent or widespread the behavior is. We documented three new scavenging events from North America and Europe, and also performed a systematic literature review of the reports documenting scavenging by owls. The number of such reports was similar in each decade from the 1970s to the 2000s, but the decade of the 2010s had more reports than all previous decades combined. Owls scavenged primarily on mammals (81%), followed by birds (16%) and reptiles (3%); almost half (47%) of carrion scavenged were Artiodactyla (hoofed mammals) and most of the species scavenged were larger than the feeding owl. Most reports documenting scavenging by owls were from either Europe (n=14) or North America (n=11), with few reports from Asia (n=2), South America (n =2), or Australia (n=1), and none from Africa. The most frequent type of report was direct observations (n= 14), followed by camera trapping (n=9) and pellet analyses (n=6). Our review indicates that scavenging is a widespread behavior among owl species, but most observations were opportunistic, suggesting that additional incidents of scavenging by owls are likely unobserved. Further research is needed to establish the frequency of scavenging by owls and the effects that scavenging may have on owl populations and scavenging communities. [ABSTRACT FROM AUTHOR]

The Snowy Owl (Bubo scandiacus) is a rare resident species in Iceland and nests have been found intermittently. Nests are unusual because lemmings (Dicrostonyx spp. and Lemmus spp.), the primary prey of the Snowy Owl across much of its distribution, do not occur in Iceland. We studied summer diets by analyzing pellets from three areas in Iceland where owls were detected; breeding was confirmed at two of these sites. We identified 257 prey items (total mass of 73.6 kg) of at least 13 species. Birds made up most of the diet (96.5% by number). The Rock Ptarmigan (Lagopus muta) was the primary prey species (30.4%). Shorebirds were important prey (46.2%), and passerines (5.1%), as well as waterfowl (6.3%), were also taken. Wood mice (Apodemus sylvaticus; 2.7%) and Arctic fox pups (Vulpes lagopus; 0.8%) were taken occasionally. Adult prey birds made up 60.3% and nestlings 36.3% of the diet by number. [ABSTRACT FROM AUTHOR]

Populations of Leach's Storm-Petrels (Oceanodroma leucorhoa) are in decline globally, but causes of these declines are unclear. One possibility is predation at breeding colonies. To estimate effects of one pair of Great Horned Owls (Bubo virginianus) on a Leach's Storm-Petrel colony, we analyzed owl pellets collected from Bon Portage Island, Nova Scotia, Canada, over 5 consecutive breeding seasons (2011–2015). Great Horned Owl diets were mainly Leach's Storm-Petrels by number (79%) and by mass (66%). Muskrats (Ondatra zibethicus), meadow voles (Microtus pennsylvanicus), and masked shrews (Sorex cinereus) completed the diet. This is, to our knowledge, one of the most specialized diets reported for this species of owl. We estimate that this specialized diet reduced by at most 1% annually the population of Leach's Storm-Petrels on this island. [ABSTRACT FROM AUTHOR]

This study investigated the dietary niche of the Barn Owl (Tyto alba) in an intensively farmed landscape, based on pellet samples from 12 nesting pairs containing 25 animal taxa and 1,994 prey items after the breeding season in 2016. Based on land use categories of the buffer area around each nest, three landscape types (agricultural, mosaic, urban) were considered, to analyse the diet composition and food-niche parameters. Niche breadth was calculated at the local and landscape level. Small mammals were the most frequent in the diet than other prey in each of the landscape types. The Common Vole (Microtus arvalis), considered to be an important agricultural pest was the most numerous prey in all landscape groups. The trophic niche of Barn Owl varied between 0.69 - 0.86 at the local level, and the overall value of niche breadth was significantly higher in the urban than in the other two landscape types. Our results showed that the increase of Common Vole frequency lead to a decrease in niche breadth; significantly negative relationship was detected between these parameters. Despite differences in niche breadth, similarly high niche overlaps were detected by the randomisation test in the three landscapes. Our results suggest that the diet composition of Barn Owls, mainly their food-niche pattern, reflected prey availability in the comparison of the studied landscapes, which pointed out that it is necessary to examine the dietary difference of Barn Owls at the finer scale of land use. [ABSTRACT FROM AUTHOR]

Long-eared Owls (Asio otus) usually winter in groups in settlements, hunt at night and rest in evergreen trees during the day. From prey remnants regurgitated as pellets, one can detect species present in their hunting areas and changes in their abundance. Our aim was to reveal how the ratio of small mammal species in Long-eared Owl prey changes during the winter, since weather can influence hunting success and the availability of prey. There were 40-60 Long-eared Owls wintering in the city of Pécs. From November 2014 to mid-March 2015 we collected 6,328 pellets from which 9,087 prey remains were identified. 97.5% of prey consisted of small mammals belonging to 21 species. The diversity of small mammals in the pellets collected in November was significantly lower in comparison with other months. With the increase of precipitation, the relative abundance of the Common Vole (Microtus arvalis) and Common Dormouse (Muscardinus avellanarius) decreased, while that of the Striped Field Mouse (Apodemus agrarius) and Wood Mouse (A. sylvaticus) increased. In the periods when the area was covered by snow, the ratio of the Common Vole as prey continually decreased, probably because it stayed under the snow. Since the availability of the Common Vole declined, the proportions of the Striped Field Mouse and Lesser White-toothed Shrew (Crocidura suaveolens) as alternative prey grew significantly. In low temperature periods, Brown Rats (Rattus norvegicus) and birds are more often preyed upon. Despite the hunting area being predominantly urban, species preferring open grassland habitats were significantly more common. As winter progressed, the role of forest-dwelling species in the diet continuously increased. [ABSTRACT FROM AUTHOR]

The feeding of Little Owl (Athene noctua) was studied in a farmland area of Kiskunság, Central Hungary. For the analyses, a total of 661 Little Owl pellets were collected between February and September 2005 from three locations, corresponding known Little Owl territories situated nearby the settlements Apaj, Kunpeszér and Ladánybene. The aim of the present study was to explore the diet composition of Little Owl and to give a detailed evaluation of the arthropod diversity based on the pellet analysis. The identified prey items represented 15 vertebrate and 39 invertebrate species/taxa. In terms of prey number, dominance of small mammals was observed in two sites (Apaj - 55%, Kunpeszér - 68%), while birds and mammals shared almost equal dominance (~25%) in Ladánybene. The most numerous mammal species was the Common Vole (Microtus arvalis), while the Starling (Sturnus vulgaris) played key role among the birds. Contribution of amphibian Common Spadefoot (Pelobates fuscus) was considerable, while share of reptiles was marginal. Vertebrates also played a predominant role by contributing over 99% of the overall prey biomass in all study sites. Invertebrate prey dominance ranged from 24.8-30.0% while their contribution to the overall biomass was very low (0.14-0.34%). Large sized beetles (Pentodon idiota, Melolontha hippocastani) and orthopterans (Tettigonia viridissima, Gryllotalpa gryllotalpa) were preferred. Arthropod species richness and diversity were the highest in Kunpeszér, supposedly owing to the rich mosaic habitat structure. [ABSTRACT FROM AUTHOR]

Three cases of carrion-feeding with remains of artiodactyls (0.3%, n=1104 samples with food remains) have been documented in a long term diet study of Eurasian Eagle-owls (Bubo bubo) in 53 localities at Southeastern Bulgaria. Bone pieces of a sheep/goat (Ovis aries/Carpa hircus), a Fallow Deer (Dama dama) and a Domestic Pig (Sus scrofa dom.) in three Eurasian Eagle-owl breeding localities (5.7%) prove extremely rare feeding on carrion. Northern White-breasted Hedgehog (Erinaceus roumanicus), rats (Rattus sp.), waterbirds and gallinaceous birds (total 59.5-72.6% by biomass) constituted the main portion of the diets with carrion remains. The comparisons between food niche breadths, diet composition, average prey biomass and values of superpredation of the annual diets in the three localities have not supported the carrion-feeding of the Eurasian Eagle-owl as a result of food shortages. [ABSTRACT FROM AUTHOR]

We analyzed seasonal changes in Tawny Owl (Strix aluco) diet in a broadleaved forest in Eastern Ukraine over 6 years (2007-2012). Annual seasons were divided as follows: December-mid-April, April-June, July-early October, and late October-November. In total, 1648 pellets were analyzed. The most important prey was the bank vole (Myodes glareolus) (41.9%), but the yellow-necked mouse (Apodemus flavicollis) (17.8%) dominated in some seasons. According to trapping results, the bank vole was the most abundant rodent species in the study region. The most diverse diet was in late spring and early summer. Small forest mammals constituted the dominant group in all seasons, but in spring and summer their share fell due to the inclusion of birds and the common spadefoot (Pelobates fuscus). Diet was similar in late autumn, before the establishment of snow cover, and in winter. The relative representation of species associated with open spaces increased in winter, especially in years with deep snow cover, which may indicate seasonal changes in the hunting habitats of the Tawny Owl. [ABSTRACT FROM AUTHOR]

Coexistence of predator species often depends on behaviours or preferences that result in spatiotemporal 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. [ABSTRACT FROM AUTHOR]

The diet composition of long-eared owls in central Poland was studied in the years 2004-2010 using standard procedures entailing the analysis of pellets. A total of 2111 prey items were identified in the material analysed, and voles (Microtus spp.) were found to dominate in both the summer (April-September) and winter (October-March) seasons. Nevertheless, the owls consumed voles and all rodents significantly more often in winter, while taking birds and insects significantly more often in spring and summer. The food-niche breadth was thus greater in the summer period. Overall, the results confirm the dietary specialisation of long-eared owls toward predation on rodents of the genus Microtus. [ABSTRACT FROM AUTHOR]

This study of the diet of Barn Owl Tyto alba analyzed pellets containing 18,810 prey specimens. Small mammals (98.2% by number, 97.5% by biomass) dominated, while birds, reptiles, amphibians, and insects constituted a negligible portion of the diet (1.8% by number, 2.5% by biomass). Voles (Microtus spp.) were the most numerous prey (35.3 ± 14.4%, range 14.6%-67.1%) in 9 localities (69.2%, n = 13 individually studied localities) and dominated the biomass in all diets (51.4 ± 14.1%, range 27.4%-78.2%). The lesser white-toothed shrew (Crocidura suaveolens) (20.8 ± 7.6%, range 7.3%-32.8%) was the most frequent prey in the other 4 localities (30.8%). The breeding localities with more similar proportions of habitats in their hunting territories had significantly higher diet overlaps (r = 0.336, P < 0.01). The amount of wetlands and the indices of habitat heterogeneity and topographic relief among the landscape characteristics of the hunting territories significantly influenced diet composition according to redundancy analysis. Larger areas of wetlands correlated with higher predation on wetland mammal species, as well as the European pine vole (Microtus subterraneus) and white-toothed shrews, and thus with broader food niche breadth. [ABSTRACT FROM AUTHOR]

The Long-eared Owl (Asio otus) is a widely distributed predator with plastic foraging habits. Its diet has been studied across most of Europe and North America, but little information is available on intra-seasonal diet variation. We studied the winter diet of Long-eared Owls in a Mediterranean fragmented farmland. Diet was dominated by small mammals (mostly Apodemus spp.), with birds the second most abundant group. In our landscape, the amount of bird prey items in the diet was higher compared to values reported from other areas of Italy. There was relatively large variation in the diet among the three months of study. Our study confirms the pattern of higher Long-eared Owl diet diversity in a Mediterranean landscape compared to that reported for other regions of Europe where the diversity of prey species may be lower. The findings suggest that extensively-managed Mediterranean rural landscapes can provide habitat suitable for the Long-eared Owl, as they offer a wide diversity of food sources that may be exploited by this nocturnal predator. [ABSTRACT FROM AUTHOR]

We report the first study to compare the contents of pellets and regurgitates of South Polar Skuas, Stercorarius maccormicki, at two breeding colonies on the Antarctic Peninsula. Samples were taken across years from identified breeding pairs at Potter Peninsula in sympatry with 30-40 breeding pairs of Brown Skuas, Stercorarius antarcticus lonnbergi, and from Cierva Point with 2 pairs of Brown Skuas. In contrast to the general consensus that penguins feature in the diet most prominently in the absence of Brown Skuas, we found a much more frequent occurrence of penguin remains in samples at Potter than Cierva, but only in pellets. At Cierva, penguin feathers were largely replaced in the pellets by a high frequency of non-food moss. The rare occurrence of penguins in regurgitates from both sites is consistent with scavenging rather than active predation. The high frequency of feathers in pellets at Potter is consistent with a gut-cleansing function similar to that performed by moss, which is abundant only at Cierva. We conclude that pellets over-represent penguins in the diet. For any species that consumes feathers, the evidence must consider the alternative possibility of a non-food function of ingesting feathers. [ABSTRACT FROM AUTHOR]

The article presents a study on the use of stable isotopes to identify dietary patterns in the nestlings of Bonelli's Eagle. The researchers observed 15 territorial breeding pairs of the bird in Catalonia, Spain, and used pellet analysis as basis for the conventional diet study. They also conducted a Spearman rank correlation test to analyze if isotopic data from nestlings were related to their diet. They found that the important changes in Mediterranean landscapes in terms of human activity and the extent of the various kinds of land use have influenced the abundance and distribution of Bonelli's Eagle prey.

The article discusses research which examined the temporal changes in the diet of the Lesser Kestrel also called Falco naumanni during the breeding season in the southern part of Spain. The researchers examined the diet composition of the species in terms of prey richness of each pellet, frequency of occurrence of different prey as well as mean prey weight. They found that the mean weight of their prey increases as the breeding season advances. A description of the study area, pellet collection and prey identification is also provided.

Analyses of feces, stomach contents, and regurgitated pellets are common techniques for assessing diets of vertebrates and typically contain more than 1 food item per sampling unit. When analyzed, these individual food items have traditionally been treated as independent, which represents pseudoreplication. When food types are recorded as present or absent, these samples can be treated as multinomial vectors of food items, with each vector representing 1 realization of a possible diet. We suggest such data have a similar structure to capture histories for closed-capture, capture--mark--recapture data. To assess the effects of landscapes and presence of a potential competitor, we used closed-capture models implemented in program MARK into analyze diet data generated from feces of swift foxes (Vulpes velox) and coyotes (Canis latrans) in northwestern Texas. The best models of diet contained season and location for both swift foxes and coyotes, but year accounted for less variation, suggesting that landscape type is an important predictor of diets of both species. Models containing the effect of coyote reduction were not competitive (ΔQAICc = 53.6685), consistent with the hypothesis that presence of coyotes did not influence diet of swift foxes. Our findings suggest that landscape type may have important influences on diets of both species. We believe that multinomial models represent an effective approach to assess hypotheses when diet studies have a data structure similar to ours. [ABSTRACT FROM AUTHOR]

The article presents a study which examined bat predation by the barn owl Tyto alba in a hibernation sites of bats. It states that based on numerous studies of owl pellets, bats are not commonly represented in the prey of the barn owl and usually make up less than 1% of the prey individuals. It mentions that the prey remains of the barn owl from the fortress Dömitz, southeast of Mecklenberg-Western Pomerania, Germany, were investigated. It notes that the high frequency of bats from the 2002 sample led to a total percentage of bats of almost 39% and bats were clearly dominant over other potential prey groups. It adds that the findings reveal that Tyto alba is an opportunistic but no selective hunter of bats.

Simple Summary: Predators may present various feeding strategies, i.e., being either food specialists or opportunists. At the same time, their diets change to reflect the prey availability and to avoid competition for food resources. We performed this research in a highly transformed field and forest mosaic and in an area with a high abundance of avian predators (owls and birds of prey, ~133 breeding pairs in total). We calculated the food niche overlap statistics to show the competition for food resources between coexisting species. We assessed the diet composition on the basis of pellet analyses and the identification of prey remains collected from under nests during the breeding season. The food niches overlapped moderately with only one exception, i.e., the highest niche overlap was recorded for the common buzzard and common kestrel, two species preying in open spaces on field rodents but switching to soricomorphs when the former were scarce. On the contrary, the most separate food niche was that of the white-tailed eagle, which was the only species regularly preying on fish. Our results showed that the food niches of species coexisting in the same area were considerably separate, which is due to the fact that they prey on various prey species or search for them in different habitats. Food niche overlap statistics are a common way to show competition for food resources in a group of animals. Niche breadths of various species are very variable and their diet composition changes reflecting prey availability. The aim of this study was to evidence the food niche overlap of the whole assemblage of avian predators (eight raptor and owl species, some of them reaching very high densities) in a field and forest mosaic of central Poland. The diet composition was assessed on the basis of pellet analyses and the identification of prey remains found under the nests in the breeding period. The extent of the niche overlap was calculated using a Pianka formula. The food niche overlap indices ranged from 0.02 to 0.93 (mostly below 0.5). The most separate food niche was that of the white-tailed eagle, who regularly preyed on fish. The highest niche overlap was recorded for the common buzzard and common kestrel, two species preying on field rodents, switching to soricomorphs when the former were scarce. Our results confirmed that the food niches of species coexisting in the same area were considerably separate, which is a result of preying on various prey species or searching for them in different habitats. [ABSTRACT FROM AUTHOR]

Simple Summary: The population of goshawks crashed in the middle of the 20th century due to persecution, forest management practices, and the usage of toxic pesticides (DDT) in agriculture. Now, it has rebuilt, yet the population trend is not equal across countries. Here, we focused on a goshawk population in central Poland for which monitoring started in the 1980s (high densities were recorded at that time of 16.3 pairs/100 km2) to see how changing environmental factors influenced the current population trend. In the field and forest mosaic, these birds build their nests in small forest complexes, but important prey tend to be caught near farmsteads. This has previously resulted in the persecution of the birds by farmers. Anthropogenic food (poultry and domestic pigeons) played a key role in their population density. Consequently, when the anthropogenic food base was limited (due to changes in the Polish farmland), population abundance dropped by half. As supplementary prey (including small-game and most corvid species) were not abundant, goshawks could not replace their staple food of anthropogenic origin. This demonstrates the complex way in which socioeconomic changes in agriculture can influence a raptor population: both positively (fewer cases of persecution are being recorded now) and negatively (small-scale breeding of pigeons and poultry became unimportant and unprofitable, and small game abundance decreased due to changes in farming practices and farmland structure). In this study, we focused on a goshawk population in central Poland (study area 105 km2, forests 24 km2, seven small forest complexes) which was monitored long-term (with high densities recorded in the 1980s of 16.3 pairs/100 km2 despite persecution by farmers) to analyse how environmental factors (prey availability and changes in the forest structure) influenced population abundance, breeding parameters, and diet composition. The study was undertaken from 2011–2018, and the results were compared with published data from two previous study periods (1982–1992 and 2001–2003). The number of breeding pairs dropped from 17.1 to 8.0; the breeding success was around 75% in all study periods. The selection of nesting trees followed the changes in stand species and age structure. More nesting attempts per one nest were recorded in the current time period (1.7 vs. 1.1), which probably reflected lower anthropopressure (i.e., no cases of persecution were recorded in this study). Diet composition seemed to follow changes in the prey availability: The share of domestic pigeons and poultry (the main prey in the 1980s) as well as small game dropped, while the share of Eurasian jay and wood pigeon increased. Our studies suggested that anthropogenic food (poultry and domestic pigeons) played a key role for the goshawk population in the transformed habitats of the field and forest mosaic. [ABSTRACT FROM AUTHOR]