When carnivores are “full and lazy”

Jeschke, Jonathan M.

doi:10.1007/s00442-006-0654-2

Cited by 59 publications

(80 citation statements)

References 54 publications

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“…A recent study, however, suggests that the assumption that predators are normally energy-limited is likely to be an over-simplification [46]. In almost 90 per cent of the vertebrate species examined, the kill rates of prey exceeded the energetic demands of the predators, suggesting that energy intake in predators is unlikely to be as limiting as once believed.…”

Section: Results (A) Effects Of Lipid and Protein Intake On Egg Produmentioning

confidence: 97%

Optimal foraging for specific nutrients in predatory beetles

et al. 2012

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Evolutionary theory predicts that animals should forage to maximize their fitness, which in predators is traditionally assumed equivalent to maximizing energy intake rather than balancing the intake of specific nutrients. We restricted female predatory ground beetles (Anchomenus dorsalis) to one of a range of diets varying in lipid and protein content, and showed that total egg production peaked at a target intake of both nutrients. Other beetles given a choice to feed from two diets differing only in protein and lipid composition selectively ingested nutrient combinations at this target intake. When restricted to nutritionally imbalanced diets, beetles balanced the over-and under-ingestion of lipid and protein around a nutrient composition that maximized egg production under those constrained circumstances. Selective foraging for specific nutrients in this predator thus maximizes its reproductive performance. Our findings have implications for predator foraging behaviour and in the structuring of ecological communities.

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Section: Results (A) Effects Of Lipid and Protein Intake On Egg Produmentioning

confidence: 97%

Optimal foraging for specific nutrients in predatory beetles

et al. 2012

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“…Comparing kill rates in number of ungulates/week suggests that pumas exhibit strong seasonal variation, whereas comparing kill rates in kg/day suggests that regardless of number of animals killed per unit time, pumas kill an equivalent amount of meat. Kill rates in kg/day suggest that pumas might be following or meeting some energetic threshold irrespective of prey availability (Jeschke 2007). However, when observing the kill-rate metrics together, they point to the complexity of predator-prey relationships in a multipredator system.…”

Section: Discussionmentioning

confidence: 97%

Seasonal variation in the feeding ecology of pumas (Puma concolor) in northern California

et al. 2014

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Direct effects of predators depend upon factors that can vary across seasons, including variations in the abundance and vulnerability of migrating prey. Past studies show conflicting results of whether puma (Puma concolor (L., 1771)) feeding ecology varies among seasons. We employed GPS collars to study puma feeding ecology in a single-prey system with migratory black-tailed deer (Odocoileus hemionus columbianus (Richardson, 1829)). We hypothesized that puma feeding ecology would vary based on changes in prey abundance and spatial distribution, as well as competition with scavengers and decomposers. Our results supported these hypotheses. Kill rates in number of ungulates/week were significantly higher in summer and autumn than in winter, likely owing to the increased availability and density of black-tailed deer fawns. The handling times of blacktailed deer ≥1 year old were significantly higher in winter than in spring, summer, or autumn. We speculated that reduced handling time in summer may have been influenced by black bear (Ursus americanus Pallas, 1780) kleptoparasitism and the decomposition of kills. Pumas killed black-tailed deer at higher elevations in summer than in winter, spring, or autumn, and the elevations correlated significantly with seasonal elevations used by black-tailed deer, suggesting that pumas exhibited seasonal foraging behaviours and tracked prey availability in a system with migrating prey.Résumé : Les effets directs de prédateurs dépendent de facteurs qui peuvent varier selon les saisons, y compris des variations de l'abondance et de la vulnérabilité de proies migratrices. Des études antérieures ont produit des résultats contradictoires quant à d'éventuelles variations de l'écologie alimentaire du couguar (Puma concolor (L., 1771)) selon la saison. Nous avons utilisé des colliers GPS pour étudier l'écologie alimentaire du couguar dans un système à proie unique, à savoir le cerf mulet migrateur (Odocoileus hemionus columbianus (Richardson, 1829)). Nous avons postulé que l'écologie alimentaire du couguar variait selon les variations de l'abondance et de la répartition spatiale des proies, ainsi que la concurrence de détritivores et de décomposeurs. Nos résultats appuient ces hypothèses. Les taux de capture en ongulés/semaine étaient significativement plus élevés à l'été et l'automne qu'à l'hiver, vraisemblablement en raison de la disponibilité et la densité accrues de paons de cerf mulet. Les temps de consommation de cerfs mulets de ≥1 an étaient significativement plus élevés en hiver qu'au printemps, en été et en automne. Nous pensons que les temps de consommation plus courts durant l'été pourraient avoir être influencés par le cleptoparasitisme d'ours noirs (Ursus americanus Pallas, 1780) et la décomposition des captures. Les couguars tuaient des cerfs mulets à de plus hautes altitudes en été qu'en hiver, au printemps et en automne, et les altitudes étaient significativement corrélées aux altitudes saisonnières fréquentées par les cerfs mulets, ce qui donne à penser que les couguars f...

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“…If digestion-limitation indeed occurs much more often than collection-limitation (Jeschke et al, 2002;Jeschke, 2007), then food quality may be a much more important factor controlling habitat quality than, for example, food density. When digestion-limited, animals can't get a higher food intake at a higher food density, whereas they can at a higher food quality (Van Gils et al, 2006b).…”

Section: Please Scroll Down For Articlementioning

confidence: 97%

“…by contrast, a forager is digestion-limited when digestion cannot keep up with the rate at which food is collected. This usually occurs when food is abundant and handling time is negligible (Jeschke, 2007). Recently, Jeschke et al, (2002) suggested that digestion-limited foraging is much more widespread than collection-limited foraging.…”

Section: Please Scroll Down For Articlementioning

confidence: 99%

Digestive Organ Size and Behavior of Red Knots (Calidris Canutus) Indicate the Quality of Their Benthic Food Stocks

Gils

Dekinga

Hout

et al. 2007

Israel Journal of Ecology & Evolution

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Digestive organ size anD behavior of reD knots (Calidris Canutus) inDicate the quality of their benthic fooD stocksAbSTRACT Assuming that animals respond optimally to environmental changes, both behavior and physiology should be useful indicators of the way that animals perceive the quality of their environment. For verification, we examined foraging time and gizzard size of the red knot (Calidris canutus), a long-distance migrant shorebird that ingests hard-shelled mollusk prey whole and therefore readily faces digestive constraints. Nevertheless, even when digestively bottlenecked, knots can still enhance their daily energy intake by flexibly increasing the size of their digestive system, notably the gizzard, and/or by feeding longer per day. Whether such adjustments are actually necessary depends on the quality (condition) of their food, i.e., the ratio of flesh to shell mass. Hence, gizzard mass and daily foraging time in knots may be reliable indicators of the quality of their invertebrate prey. This idea is explored by using field data on radio-marked knots during late summer in the Dutch Wadden Sea. Their gizzards were measured using ultrasonography and the knots' movements and working hours were monitored using handheld receivers and automated radio-tracking systems. Indeed, gizzard mass alone predicted annual variation in food quality satisfactorily; however, adding estimates for daily foraging time significantly improved the predictions. We discuss and conceptualize how knots may trade off digestive organ size against foraging time upon arrival in the Wadden Sea, given the quality and quantity of the food on offer, and why these findings are relevant in the context of conservation of migration systems.

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When carnivores are “full and lazy”

Cited by 59 publications

References 54 publications

Optimal foraging for specific nutrients in predatory beetles

Optimal foraging for specific nutrients in predatory beetles

Seasonal variation in the feeding ecology of pumas (Puma concolor) in northern California

Digestive Organ Size and Behavior of Red Knots (Calidris Canutus) Indicate the Quality of Their Benthic Food Stocks

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