Search results for "Predation"
showing 10 items of 589 documents
Macroscopic Dynamic Effects of Migrations in Patchy Predator-prey Systems
1997
Abstract Different mechanisms at the behaviourial or physiological levels determine many properties of predator-prey systems at the population level. In this paper, we present a method of obtaining complex predator-prey dynamic models from models at a detailed, behaviourial level of description. We consider a multi-patch predator-prey model, the dynamics of which contains two time-scales: a fast one, associated with migrations between patches, and a slow one, on which interactions, reproduction and mortality occur. We use methods of perturbation theory in order to aggregate the multi-patch system into a reduced system of two differential equations for the total prey and predator populations…
Data from: Gray plumage color is more cryptic than brown in snowy landscapes in a resident color polymorphic bird
2020
Camouflage may promote fitness of given phenotypes in different environments. The tawny owl (Strix aluco) is a colour polymorphic species with a grey and brown morph resident in the Western Palearctic. A strong selection pressure against the brown morph during snowy and cold winters has been documented earlier but the selection mechanisms remain unresolved. Here we hypothesise that selection favors the grey morph because it is better camouflaged against predators and mobbers in snowy conditions compared to the brown one. We conducted an online citizen science experiment where volunteers were asked to locate a grey or a brown tawny owl specimen from pictures taken in snowy and snowless lands…
Predatory interactions between a cyclopoid copepod and three sibling rotifer species
2002
SUMMARY 1. Cyclopoid copepod predation on rotifers affects the dynamics and structure of zooplankton communities. We address the differential vulnerability of three sympatric rotifer sibling species belonging to the Brachionus plicatilis species complex. These co-occur with their cyclopoid predator, Diacyclops bicuspidatus odessanus. 2. Using video recording and tracking, we analysed the steps in predation including attack distance, attack angle, and rotifer species swimming in the presence and absence of the predator. Our results show the greater vulnerability of B. rotundiformis (the smallest species) to D. b. odessanus predation, which is associated with a high percentage of attacks afte…
Zooplankton dynamics during autumn circulation in a small, wind-sheltered, Mediterranean lake
2006
12 pages, and tables statistics.
Intraguild interactions between two egg parasitoids exploring host patches
2010
Intraguild interactions between two egg parasitoids, Trissolcus basalis (Hymenoptera: Scelionidae) and Ooencyrtus telenomicida (Hymenoptera: Encyrtidae), exploring egg masses of the Southern Green Stink Bug (SGSB) Nezara viridula (Heteroptera: Pentatomidae), were investigated in laboratory conditions by single, simultaneous and sequential host attack experiments. Mortality of N. viridula eggs was higher in simultaneous and sequential releases compared to single species releases. In simultaneous host exploitations, T. basalis females displayed an aggressive behavior against O. telenomicida females. The outcome of multiparasitism showed that interspecific larval competition was dominated by O…
Comments on Guimarães & Sawaya. Pretending to be venomous: is a snake's head shape a trustworthy signal to a predator?
2011
Several species of non-venomous snake are known to flatten their heads when disturbed, and this behaviour has been suggested to be a mimicry of vipers (Arnold & Ovenden 2002, Hailey & Davies 1986, Young et al. 1999). Using plasticine models, Guimaraes & Sawaya (2011) tested the antipredatory function of a triangular head shape in snakes. Their article presents the first published empirical experiment testing the adaptive significance of vipers’ triangular head shape. Guimaraes & Sawaya (2011) found no support for the viper mimicry hypothesis. Accordingly, they concluded that ‘the shape of [the] head seemed not to confer advantage itself’. Although the use of plasticine models is a generally…
The complex business of survival by aposematism.
2005
The theory of warning signals dates back to Wallace but is still confusing, controversial and complex. Because predator avoidance of warningly coloured prey (aposematism) is based upon learning and reinforcement, it is difficult to understand how initially rare conspicuous forms subsequently become common. Here, we discuss several possible resolutions to this apparent paradox. Many of these ideas have been largely ignored as a result of implicit assumptions about predator behaviour and assumed lack of variation in the predators, prey and the predation process. Considering the spatial and temporal variation in and mechanisms of behaviour of both predators and prey will make it easier to unde…
Parasite-induced change in host behaviour and susceptibility to predation in an eye fluke–fish interaction
2004
Abstract Trophically transmitted parasites may increase their transmission efficiency by altering the behaviour of infected hosts to increase their susceptibility to predation by target hosts (the next host in the life cycle). The parasite Diplostomum spathaceum (Trematoda) reduces the vision of its fish intermediate hosts: its metacercariae lodge themselves in the eyes of fish and induce cataract formation, which gives them the opportunity to affect fish behaviour. We examined whether D. spathaceum eye flukes change the preference of fish for the surface layers of the water column or their escape behaviour, which could make the fish more vulnerable to predation by bird hosts. We also studi…
Ophichthids (Ophichthidae: Anguilliformes) within the body cavity of marine fishes: pseudoparasites?
2011
4 pages, 2 figures, 1 table
Risk of predation and foraging sites of individuals in mixed-species tit flocks
1993
Abstract Abstract. Foraging sites of individual willow tits, Parus montanus, and crested tits, P. cristatus, on spruce were studied in a winter when the risk of predation from pygmy owls, Glaucidium passerinum, was high and in a winter when it was low. Mixed-species flocks consisted of two crested tits (a pair) and three to six willow tits. The risk of predation from owls is likely to be highest on the most exterior tree parts. Female crested tits foraged further out on the branches than other individuals when predation risk was low, but foraged in the safer sites close to the tree trunk when the risk was high. Male crested tits retained both their relative distance to the trunk and their r…