Search results for "Predation"
showing 10 items of 589 documents
Inferring species interactions from ecological survey data: a mechanistic approach to predict quantitative food webs of seed-feeding by carabid beetl…
2020
AbstractEcological networks are valuable for ecosystem analysis but their use is often limited by a lack of data because many types of ecological interaction, e.g. predation, are short-lived and difficult to observe or detect. There are different methods for inferring the presence of interactions, which we lack methods to predict interaction strengths and so use weighted network analysis.Here, we develop a trait-based approach suitable for creating quantitative networks, i.e. with varying interaction strengths. We developed the method for seed-feeding carabid ground beetles (Coleoptera: Carabidae) although the principles can be applied to other interactions.We used existing literature data …
Characterization of trophic links in an agrosystem : weed seed predation by carabid beetles
2012
Agroecology gives evidence of new perspectives in agriculture, and open doors for alternative weed management approaches through different regulation mechanisms. Seed predation is one of them, and the interest is growing to deepen knowledge, relative to this process. This Phd work aims (i) to describe weed seed predation, the dominant carabid predators and the available resource at a local scale in a common crop (winter wheat); (ii) to study predation profiles of main predators, and the pair-wise correlations between the biological components of the system; (iii) to bring new insights regarding potential regulation of weed communities, through seed predation by carabid beetles. Complementar…
The role of biotic interactions in a prey-predator system : the case of predation and regulation of weed seeds by carabids.
2020
For the transition towards agricultural production systems that are less dependent on herbicides, the use of weed regulation by seed-eating carabids is of great interest. Weed seed predation by carabids is variable and occurs within a complex context of many biotic interactions. This complexity partly explains our current inability to predict levels of in-field weed regulation. In this thesis, I analysed variations in the levels of predation and biological regulation of weeds and determined how they respond to two classes of biotic interactions: 1) the availability of alternative prey; and, 2) intra- and inter-specific interactions between the carabids themselves. Field measurements carried…
From deception to frankness: Benefits of ontogenetic shift in the anti-predator strategy of alder moth Acronicta alni larvae
2014
Abstract Animals can avoid prédation by masquerading as objects that are not food to their predators. Alder moth Acronicta alni larvae go through an impressive ontogenetic change from masquerade to highly conspicuous appearance: early larval stages resemble bird droppings but in the last instar the larval coloration changes into striking yellow-and-black stripes. We hypothesized that such a change may be driven by differential prédation favoring dissimilar anti-predator strategies in different life stages. We show with a series of laboratory assays that larvae are distasteful to birds regardless of their developmental stage, suggesting that ontogenetic color change is not driven by the diff…
Younger bank voles are more vulnerable to avian predation
2008
The importance of predation on prey populations is mainly determined by the number of eaten prey. However, the total impact of predation might also be determined by the selection of certain prey individuals, e.g., different sexes or age categories. Here we tested selective predation by an avian predator, the pygmy owl ( Glaucidium passerinum (L., 1758)), on bank voles ( Myodes ( Clethrionomys ) glareolus (Schreber, 1780)). We compared the sex, age, and mass of hoarded prey with the animals snap-trapped from the field. There were no differences in the sex ratio between hoarded bank voles and those available in the field. However, hoarded voles were significantly younger than ones in the fie…
Diet of the insectivorous bat 'Pipistrellus nathusii' during autumn migration and summer residence
2013
Migration is widespread among vertebrates, yet bat migration has received little attention and only in the recent decades has a better understanding of it been gained. Migration can cause significant changes in behaviour and physiology, due to increasing energy demands and aerodynamic constraints. Dietary shifts, for example, have been shown to occur in birds before onset of migration. For bats, it is not known if a change in diet occurs during migration, although breeding season–related dietary preference has been documented. It is known that a diet rich in fats and the accumulation of fat deposits do increase the flight range of migratory bats. Some bat species can be regarded as long-dis…
Early Cambrian origin of modern food webs: evidence from predator arrow worms.
2007
7 pages; International audience; Although palaeontological evidence from exceptional biota demonstrates the existence of diverse marine communities in the Early Cambrian (approx. 540-520 Myr ago), little is known concerning the functioning of the marine ecosystem, especially its trophic structure and the full range of ecological niches colonized by the fauna. The presence of a diverse zooplankton in Early Cambrian oceans is still an open issue. Here we provide compelling evidence that chaetognaths, an important element of modern zooplankton, were present in the Early Cambrian Chengjiang biota with morphologies almost identical to Recent forms. New information obtained from the lowermost Cam…
Helminth communities of owls (strigiformes) indicate strong biological and ecological differences from birds of prey (accipitriformes and falconiform…
2012
We compared the helminth communities of 5 owl species from Calabria (Italy) and evaluated the effect of phylogenetic and ecological factors on community structure. Two host taxonomic scales were considered, i.e., owl species, and owls vs. birds of prey. The latter scale was dealt with by comparing the data here obtained with that of birds of prey from the same locality and with those published previously on owls and birds of prey from Galicia (Spain). A total of 19 helminth taxa were found in owls from Calabria. Statistical comparison showed only marginal differences between scops owls (Otus scops) and little owls (Athene noctua) and tawny owls (Strix aluco). It would indicate that all owl …
Density and activity patterns of Pallas's cats, Otocolobus manul, in central Mongolia
2021
Abstract Context. The ranges of many small, at-risk felid species occur almost entirely in unprotected areas, where research efforts are minimal; hence data on their density and activity patterns are scare. Aims. We estimated density and activity patterns of Pallas’s cats on unprotected lands in central Mongolia during two periods (May–August and September–November) in 2019. Methods. We used spatially explicit capture–recapture models to estimate population density at 15.2 ± 4.8 individuals per 100 km2. Key results. We obtained 484 Pallas’s cat images from 153 detections during 4266 camera-days. We identified Pallas’s cats using pelage markings and identified 16 individuals from 64 detectio…
Risk taking in natural predation risk gradients: support for risk allocation from breeding pied flycatchers
2011
Predation risk is vital in foraging decisions because activity involves some degree of risk. In a natural setting, predation risk shows temporal variation, which has been largely neglected in antipredator studies. We tested a prediction of the risk allocation hypothesis in which allocation to antipredator behaviours will depend on temporal variation in perceived risk. Individuals are predicted to allocate heightened antipredator behaviours to brief infrequent periods of high risk, but with increasing frequency of high-risk periods, individuals will invest less in these behaviours. We tested this prediction using pied flycatchers, Ficedula hypoleuca , breeding at different distances from spa…