Search results for "PREY"
showing 10 items of 117 documents
Analysis of the Allee threshold via moving least square approximation
2016
Cooperation is a common behavior between the members of predators species, because it can improve theirs skill in hunt, especially in endangered eco-systems. This behavior it is well known to induce the Strong Allee effect, that can induce the extinction when the initial populations’ is under a critical density called ”Allee threshold ”. Here we investigate the impact of the pack hunting in a predator-prey system in which the predator suffers of an infectious disease with frequency and vertical transmission. The result is a three dimensional system with the predators population divided into susceptible and infected individuals. Studying the system dynamics a scenario was identified in which…
Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs
2014
Aposematic signal variation is a paradox: predators are better at learning and retaining the association between conspicuousness and unprofitability when signal variation is low. Movement patterns and variable colour patterns are linked in non-aposematic species: striped patterns generate illusions of altered speed and direction when moving linearly, affecting predators' tracking ability; blotched patterns benefit instead from unpredictable pauses and random movement. We tested whether the extensive colour-pattern variation in an aposematic frog is linked to movement, and found that individuals moving directionally and faster have more elongated patterns than individuals moving randomly and…
Feeding habits of the Short-toed Eagle Circaetus gallicus during the breeding period in Central Italy
2022
Short-toed Eagle Circaetus gallicus is the only snake eagle that nests in the Palearctic. Its diet has been studied in several European countries and it is essentially based on reptiles. The aims of this work were to characterise the feeding habits of Short-toed Eagle breeding in the Tolfa Mountains (Central Italy) including a comparison of the diet with that of other populations. Moreover, we assessed changes in the diet of the former population using published data collected more than 35 years ago. We monitored five nests and three roosts between 2020 and 2021. Using camera traps and the collection and analysis of feeding remains, a total of 247 prey items were identified. The diet of the…
Ophichthids (Ophichthidae: Anguilliformes) within the body cavity of marine fishes: pseudoparasites?
2011
4 pages, 2 figures, 1 table
Ultraviolet reflection and predation risk in diurnal and nocturnal Lepidoptera
2004
According to our extensive data on Lepidoptera (883 species), UV wing patterns are almost three times more common in nocturnal than in diurnal Lepidoptera. This might be due to predation, because the primary diurnal predators, birds, utilize UV light in foraging and even prefer UV-reflecting prey. To test this hypothesis, we conducted a field experiment with tethered living moths whose wings were artificially manipulated to reflect (UV+, reflection at UV wavelength: 15%) or absorb (UV - ) UV light, keeping longer wavelengths identical. Thus, any difference found in survival rates would be the result of the difference in wing patterns in UV spectrum. Significantly more UV+ moths th…
Speed-accuracy trade-off and its consequences in a scramble competition context.
2014
Abstract: Animals foraging in groups commonly respond to the presence of others by increasing their foraging rate, an increase that could come at the expense of prey detection accuracy. Yet the existence and consequences of such so-called 'speed-accuracy trade-offs' in group-foraging animals remain unexplored. We used group-feeding zebra finches, Taeniopygia guttata, to determine how search speed affects food detection accuracy and how a potential speed-accuracy trade-off influences feeding success. We found significant between-individual differences in hopping speed as well as evidence that faster individuals were more likely to overlook food, demonstrating the existence of a trade-off bet…
Disentangling local agronomic practices from agricultural landscape effects on pest biological control
2019
International audience; The biological control of crop pests is a valuable service provided by various beneficial organisms that are naturally present in agricultural landscapes. Semi-natural habitats has long been recognized as essential to preserve beneficial insects, but proof of their efficiency to enhance biological control of pests remains non conclusive. Here, we examined the variability of landscape effect on biological pest control and the way local agronomic practices may modulate it. Biological pest control was monitored in 80 commercial fields (arable crops and orchards) during three consecutive years in four contrasting French agricultural landscapes distributed along a double …
Species-specific prey choice of carabid beetles in European cereal fields
2017
National audience; Trophic interactions between species in agroecosystems provide key regulation ecosystem services and therefore also determine the dynamics, robustness and resilience of service provision. To achieve international goals of reducing application of pesticides without compromising key provisioning ecosystem services such as crop yield, recent research attaches importance to the biological control potential of carabid beetles. However, apart from feeding on pest species and weed seeds, carabids also consume non-pest prey (alternative prey) such as collembolans and earthworms, which can play a contradictory role in the efficacy of pest and weed control. Most carabids are descri…
Widespread diminishing anthropogenic effects on calcium in freshwaters
2019
Calcium (Ca) is an essential element for almost all living organisms. Here, we examined global variation and controls of freshwater Ca concentrations, using 440 599 water samples from 43 184 inland water sites in 57 countries. We found that the global median Ca concentration was 4.0 mg L−1 with 20.7% of the water samples showing Ca concentrations ≤ 1.5 mg L−1 , a threshold considered critical for the survival of many Ca-demanding organisms. Spatially, freshwater Ca concentrations were strongly and proportionally linked to carbonate alkalinity, with the highest Ca and carbonate alkalinity in waters with a pH around 8.0 and decreasing in concentrations towards lower pH. However, on a temporal…