Diet and Prey Consumption Rates of Nesting Boreal Owls, <em>Aegolius funereus</em>, in Alaska

Dietary composition and prey consumption rates of nesting Boreal Owls, Aegolius funereus, were investigated during 2004–2006 using two methods. Dietary composition was determined during nest visits through examination of 1882 fresh remains containing at least 11 mammalian and 15 avian species. Consumption rates were calculated based on laboratory examination of seven prey detritus bricks following fledging, yielding 1051 items of five different taxa. During 2003–2006, small mammal snap-trapping was conducted in the vicinity of occupied nest boxes, and relative abundance of potential prey items was estimated. A total of 4020 trap-nights yielded 695 small mammal captures of eight species. Consumption rates of nestling owls ranged from 22.0 to 29.7 g of food per day, averaging 24.2 g (SD = 1.8). Comparisons between availability of small mammals (as indicated by snap-trapping) and consumption (as indicated by nest visits and analysis of prey detritus bricks) showed that Boreal Owls are generally preying on mammals proportionate to their occurrence.

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Prey choice of Tengmalm's owls (Aegolius funereus funereus): preference for substandard individuals?

Canadian Journal of Zoology ◽

10.1139/z96-094 ◽

1996 ◽

Vol 74 (5) ◽

pp. 816-823 ◽

Cited By ~ 32

Author(s):

Vesa Koivunen ◽

Erkki Korpimäki ◽

Harri Hakkarainen ◽

Kai Norrdahl

Keyword(s):

Common Shrew ◽

Common Vole ◽

Clethrionomys Glareolus ◽

Prey Choice ◽

Aegolius Funereus ◽

Nest Boxes ◽

Bank Voles ◽

The Common ◽

Common Voles ◽

Prey Items

Errington proposed that predators mainly kill substandard prey, because dominant individuals force subordinate ones into poor habitats, where the predation risk is higher. We studied the prey choice of breeding male Tengmalm's owls (Aegolius funereus funereus) in 1992, when vole densities crashed. We trapped small mammals in the main habitat types in 21 owl territories, and simultaneously identified prey items cached by the same owls in their nest boxes. The main prey of owls in western Finland are the common vole (Microtus epiroticus), field vole (M. agrestis), bank vole (Clethrionomys glareolus), and common shrew (Sorex araneus). Common voles were the preferred prey of owls, followed by field voles, bank voles, and common shrews. Prey captured by owls tended to be lighter and smaller than those available in the field. This tendency was significant for field voles and common shrews. Field voles, common voles, and female common shrews captured by owls tended to have more internal fat than those available in the field. This tendency was significant for male field voles and female common shrews. Owls appeared to choose small individuals of some, but not all, prey species, and that these prey items were not in poor physiological condition.

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Sources of variation in the feeding ecology of the piked spurdog (Squalus megalops): implications for inferring predator–prey interactions from overall dietary composition

ICES Journal of Marine Science ◽

10.1016/j.icesjms.2005.04.004 ◽

2005 ◽

Vol 62 (6) ◽

pp. 1076-1094 ◽

Cited By ~ 31

Author(s):

J. Matías Braccini ◽

Bronwyn M. Gillanders ◽

Terence I. Walker

Keyword(s):

Spatial And Temporal Variation ◽

Dietary Composition ◽

Bootstrap Analysis ◽

Predator Prey ◽

Ecological Relationships ◽

Wide Range ◽

Opportunistic Predator ◽

Sources Of Variation ◽

Males And Females ◽

Prey Items

Abstract Sources of variation in dietary composition were examined in the piked spurdog (Squalus megalops). The species is an opportunistic predator that consumes a wide range of prey items. When importance of prey was measured by weight or occurrence, S. megalops preyed largely on molluscs and teleosts. However, when number of prey was considered, the main items were crustaceans. A bootstrap analysis showed that considerable variability can be expected in the importance of prey items in the species' overall diet. Regional, seasonal, and ontogenetic differences in dietary composition were found, but there were no differences between mature and immature sharks or between males and females. The spatial and temporal variation in diet exhibited by S. megalops and the intrinsic natural variability of the dietary composition of this opportunistic predator suggest that studies that infer predator–prey interactions from overall diet are likely to miss information on the ecological relationships among species and thus account for only part of these interactions.

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Prey consumption rates and compatibility with pesticides of four predatory mites from the family Phytoseiidae attacking Thrips palmi Karny (Thysanoptera: Thripidae)

Pest Management Science ◽

10.1002/ps.3296 ◽

2012 ◽

Vol 68 (9) ◽

pp. 1289-1295 ◽

Cited By ~ 16

Author(s):

Andrew GS Cuthbertson ◽

James J Mathers ◽

Pat Croft ◽

Nicola Nattriss ◽

Lisa F Blackburn ◽

...

Keyword(s):

Predatory Mites ◽

Prey Consumption ◽

Thrips Palmi ◽

The Family ◽

Consumption Rates

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Modeling the Effects of Predation, Prey Cycling, and Time Averaging on Relative Abundance in Raptor-Generated Small Mammal Death Assemblages

Palaios ◽

10.2110/palo.2007.p07-071r ◽

2008 ◽

Vol 23 (6) ◽

pp. 402-410 ◽

Cited By ~ 20

Author(s):

R. C. Terry

Keyword(s):

Relative Abundance ◽

Small Mammal ◽

Time Averaging ◽

Death Assemblages

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Feeding habits of the sandskate Psammobatis extenta (Garman, 1913): sources of variation in dietary composition

Marine and Freshwater Research ◽

10.1071/mf04205 ◽

2005 ◽

Vol 56 (4) ◽

pp. 395 ◽

Cited By ~ 48

Author(s):

J. Matías Braccini ◽

Jorge E. Perez

Keyword(s):

Feeding Habits ◽

Seasonal Pattern ◽

Seasonal Patterns ◽

Dietary Composition ◽

Important Prey ◽

Eastern Brazil ◽

Prey Diversity ◽

Sources Of Variation ◽

Males And Females ◽

Prey Items

Understanding the variation in the diet of skates is crucial for determining their roles in marine ecosystems. The diet of 458 sandskates, Psammobatis extenta, from Puerto Quequén, Argentina was quantified to determine whether there was geographical, sexual, ontogenetic, and/or seasonal variation in dietary composition. Cumulative prey-diversity curves reached a stable level at ~30 stomachs and thus the sample size was large enough to describe the overall diet of the sandskate. The diet comprised a variety of small invertebrates, suggesting that the sandskate is a secondary consumer (trophic level of 3.5). The most important prey items were gammarids, shrimps and, to a lesser extent, polychaete worms. A significant correlation was found between the diets of sandskates from south-eastern Brazil and Puerto Quequén, suggesting that in both locations they used similar resources and would have similar ecological roles. No difference was found between the diets of males and females, but ontogenetic and seasonal patterns were detected. Small sandskates preyed largely on gammarids and shrimps but consumed fewer polychaetes and brachyurans than larger individuals. In summer and winter, the most important prey item by number was gammarids, whereas the consumption of shrimps peaked in autumn. This ontogenetic and seasonal pattern indicates that large and small sandskates are versatile predators that can shift their diets in response to prey abundance.

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Conspecifics, not plant reproductive tissues, reduce omnivore prey consumption

10.1101/596015 ◽

2019 ◽

Author(s):

S. Rinehart ◽

J.D. Long

Keyword(s):

Population Level ◽

Field Studies ◽

Predation Rate ◽

Scale Insect ◽

Prey Consumption ◽

Intraspecific Interactions ◽

Conspecific Density ◽

Reproductive Tissues ◽

Consumption Rates ◽

Per Capita

AbstractPlant reproductive tissues (PRTs) can decrease (via reduced consumption) or increase (via numerical response) an omnivores consumption of animal prey. Although PRTs can increase predation pressure through numerical responses of omnivores, PRTs may also suppress predation by increasing omnivore interactions with conspecifics. Despite this potential, studies of the impacts of PRTs on predation by omnivores often overlook the effect of these tissues on intraspecific interactions between omnivores. We designed three studies to examine how PRTs and conspecific density impact prey consumption by ladybeetle omnivores. First, we assessed how PRTs impact scale insect consumption by isolated ladybeetles. Second, we measured how PRTs influence ladybeetle prey suppression when numerical responses were possible. Third, because initial experiments suggested the consumption rates of individual ladybeetles depended upon conspecific density, we compared per capita consumption rates of ladybeetles across ladybeetle density. PRTs did not influence prey consumption by isolated ladybeetles. When numerical responses were possible, PRTs did not influence total predation on prey despite increasing ladybeetle density, suggesting that PRTs decreased per capita prey consumption by ladybeetles. The discrepancy between our lab and field studies is likely a consequence of differences in ladybeetle density - the presence of only two other conspecifics decreased per capita prey consumption by 76%. Our findings suggest that PRTs may not alter the population level effects of omnivores on prey when omnivore numerical responses are offset by reductions in per capita predation rate.

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Diet of the Barn Owl, Tyto-Alba, in the Tanami Desert, Northern Territory

Wildlife Research ◽

10.1071/wr9890611 ◽

1989 ◽

Vol 16 (6) ◽

pp. 611 ◽

Cited By ~ 4

Author(s):

JDB Smith ◽

J Cole

Keyword(s):

Life History ◽

Small Mammals ◽

Small Mammal ◽

Barn Owl ◽

Northern Territory ◽

Tyto Alba ◽

Prey Biomass ◽

Large Fluctuations ◽

Prey Items ◽

Owl Pellets

The diet of the barn owl was determined by analysing egested pellets collected from the Tanami Desert. These data were also used to examine the distribution of small mammals in the region. Rodents were the dominant prey items, forming more than 74% of prey biomass in all samples. The dominant rodent species were those that undergo large fluctuations in population size. Notomys alexis was the dominant prey item in 15 of the 17 samples. In all samples, one or two species of rodents formed 47-100% of prey biomass. Dasyurids were relatively minor prey items, forming less than 12% of prey biomass in all samples. It is suggested that this is a reflection of their abundance relative to rodents. Bats, birds, lizards and insects combined formed less than 14% of prey biomass in all but one sample (24%). Behavioural and life-history characteristics of prey appear to affect their susceptibility to predation. The analysis of pellets proved to be a useful supplementary technique to conventional methods of surveying small mammals. All species of small mammal that could be expected were identified in owl pellets. Notomys amplus was recorded in pellets but not collected by conventional techniques.

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Post-Moult Behaviour in the Water-Stick Insect Ranatra Linearis

Behaviour ◽

10.1163/156853980x00285 ◽

1980 ◽

Vol 73 (3-4) ◽

pp. 304-324 ◽

Cited By ~ 8

Author(s):

Ann Cloarec

Keyword(s):

Environmental Factor ◽

Phase 1 ◽

Stick Insect ◽

Phase 2 ◽

Potential Prey ◽

Phase 3 ◽

Opening And Closing ◽

Prey Items ◽

Three Phases

AbstractThe four hour period in Ranatra nymphs between moulting and cuticle darkening is characterized by particular foreleg movements: (i) slow opening and closing of claws (OCT); (ii) moving foreleg femur tips towards the head (B2F). Post-moult behaviour has been divided into three phases: phase 1, lasting about 25 min, claws usually closed, few OCT movements and few B2F movements occur; phase 2 with claws open and forelegs stretched out in front, lasts on average 25 min; during longer phase 3 (205 min on average) many OCT and B2F movements occur. Age does not influence the duration of phases. The number of OCT and B2F movements during phase 3 increases significantly with age. An environmental factor such as presence of potential prey can influence this behaviour. Phases 1 and 3 last longer in absence of prey items than in their presence. The rates of B2F and OCT movements during phase 3 are significantly higher in the presence of prey, for all instars.

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