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We studied the diet and reproductive success of Great Horned Owl (Bubo virginianus) at its northern range limit during an apparent high in the Snowshoe Hare (Lepus americanus) population. We performed diet analyses using images from fixed motion sensor cameras and pellet and prey remains collected at active nests, and gathered data on breeding success through camera and visual observations. Pellet data at 14 nests produced 1277 prey records consisting of 65-95% Snowshoe Hare biomass. Great Horned Owls ate 18 different prey types, with overall biomass consisting of 93% mammal, 7% bird, and less than 1% insects, frogs, and fish. The mean prey mass of 714 g (± 34 SE) was 2-25 times the mean prey mass of studies of this species at more southerly latitudes. Camera observations showed that Great Horned Owls delivered an average of 459 g/chick/d (± 75) throughout nesting. This was significantly (P = 0.005) higher than observations from Alberta, at 328-411 g/chick/d. Pellet/prey remains data showed that Great Horned Owls delivering a higher proportion of hares to their nestlings successfully raised more chicks (χ2 1 = 6.3, P = 0.012), highlighting the importance of this prey in the population dynamics of Great Horned Owl. In addition, we observed Snowshoe Hare removing pellets beneath nest sites, revealing an apparently undocumented bias to the use of pellet analysis. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Raptor Research is the property of Raptor Research Foundation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Raptor Research is the property of Raptor Research Foundation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using pellet analysis, we characterized the diet and plastic and non-plastic debris ingestion of skuas (Catharacta spp.) during 2017–2020 summer seasons along the coastal sector of Fildes Peninsula (King George Island, Antarctica). In addition, we conducted the same analysis during the 2020 breeding season on reproductive territories of south polar (Catharacta maccormicki) and brown (Catharacta antarctica lonnbergi) skua. Our results confirm the generalist and opportunistic habits of both skua species. Additionally, it has been proposed that brown skua displaces south polar skua from penguin breeding colonies given its higher competitive abilities, and our results suggest this might not have happened during the study period. Along with evidence from other studies, this work underlines the idea that potential local anthropogenic sources of plastic and non-plastic debris at Fildes Peninsula need to be further addressed to improve current mitigation efforts. • Skuas diet and plastic and non-plastic debris ingestion were studied at Fildes Peninsula (King George Island, Antarctica). • Plastic and non-plastic debris ingestion was detected. • Local anthropogenic activities are discussed as sources of plastic and non-plastic debris at Fildes Peninsula. [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 provides information on a study which examined the diet of Great Cormorants Phalacrocorax carbo sinensis at Lake Dümmer in Lower Saxony, Germany. The most important factor determining their diet is prey availability. Researchers collected 562 pellets on 29 sampling days and they also found hard structures of 10,645 prey fishes belonging to 15 species. It also discussed biomass of prey fishes, proportions of young-of-the-year (YOY) fishes and large fishes, as well as prey species differences. Their diet in autumn and winter included unidentified small cyprinids and Ruffe, while they foraged primarily on cyprinids in spring and consumed YOY fishes in summer.

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.

Baseline information was collected on a local Eastern Screech-Owl population found in the apple-producing region of Saint-Hilaire and Rougemont, Quebec, as part of a larger study on pesticide exposure conducted between 2000 and 2003. Screech-Owls visited or occupied 41 of 89 nest boxes installed in 12 orchards and 2 control locations. The mean height of occupied nest boxes was 3.83 m (2.00 - 5.80 m). Squirrels, Sciurus and Tamiasciurius sp., and chipmunks, Tamias striatus, Northern Flickers, Colaptes auratus, and wasps were the owls' primary competitors for the boxes. Intact Screech-Owl pellets retrieved from nest boxes (n = 82) had a mean length and width of 3.57 and 1.44 cm, respectively, and weighed a mean of 1.77 g. Screech-Owls in the study area consumed a variety of small mammal, avian, insect and aquatic prey. Of these, Meadow Voles, Microtus pennsylvanicus, were the predominant prey item identified in pellets, and Mourning Doves, Zenaida macroura, were the primary avian prey found in nest boxes. In Canada, the owl's trend status remains largely unknown. The species is currently listed as "Not at Risk", based on an assessment conducted for COSEWIC in 1986. Given that a limited amount of information exists on the natural history and ecology of the species in Quebec, we also generated a map of the owl's distribution in the province, using data from ornithological databases and rehabilitation facilities. Potential risks to the species within the province, particularly pesticide exposure and habitat loss, are briefly addressed and follow-up studies are discussed. [ABSTRACT FROM AUTHOR]