نتایج جستجو برای: predation
تعداد نتایج: 12312 فیلتر نتایج به سال:
Prey at risk of predation may experience stress and respond physiologically by altering their metabolic rates. Theory predicts that such physiological changes should alter prey nutrient demands from N-rich to C-rich macronutrients and shift the balance between maintenance and growth/reproduction. Theory further suggests that for ectotherms temperature stands to exacerbate this stress. But the b...
Bird and arthropod predation is often associated with natural pest control in agricultural landscapes, but the rates of predation may vary with the amount of tree cover or other environmental factors. We examined bird and arthropod predation in three tree-rich and three tree-poor landscapes across southwestern Ethiopia. Within each landscape we selected three tree-rich and three tree-poor homeg...
Increasingly, ecologists emphasize that prey frequently change behaviour in the presence of predators and these behavioural changes can reduce prey survival and reproduction as much or more than predation itself. However, the effects of behavioural changes on survival and reproduction may vary with prey density due to intraspecific competition. In field experiments, we varied grasshopper densit...
Through laboratory experiments, we analysed the influence of spatial heterogeneity on predation by Mesostoma ehrenbergii on the calanoid Boeckella gracilis and the cyclopoid Acanthocyclops robustus in four horizontal and two vertical spatial arrangements. This spatial heterogeneity simulated that of Juncaceae stems, a major macrophyte in the natural environment of these zooplankton. Our results...
Artificial nest experiments (ANEs) are widely used to obtain proxies of natural nest predation for testing a variety of hypotheses, from those dealing with variation in life-history strategies to those assessing the effects of habitat fragmentation on the persistence of bird populations. However, their applicability to real-world scenarios has been criticized owing to the many potential biases ...
The interactions between predator and prey represent some of the most dramatic events in nature and constitute a matter of life and death for both sides. The hypothalamus has been implicated in driving predation and evasion; however, the exact hypothalamic neural circuits underlying these behaviors remain poorly defined. Here, we demonstrate that inhibitory and excitatory projections from the m...
Predation can cause morphological divergence among populations, while ontogeny and sex often determine much of morphological diversity among individuals. We used geometric morphometrics to characterize body shape in the livebearing fish Brachyrhaphis rhabdophora to test for interactions between these three major shape-determining factors. We assessed shape variation between juveniles and adults...
Studies that rigorously measure the effectiveness of anti-predator traits in complex ecological communities are rare. Rarer still are studies that compile the results of these trait analyses in a framework that explains the variation in predation pressure by a predator assemblage. Here the risk of predation by ants is quantified for a community of caterpillar species that employ several putativ...
Depredation of southern rock lobster (Jasus edwardsii) within fishing gear by the Maori octopus (Pinnoctopus cordiformis) has economic and ecological impacts on valuable fisheries in South Australia. In addition, depredation rates can be highly variable resulting in uncertainties for the fishery. We examined how in-pot lobster predation was influenced by factors such as lobster size and sex, se...
New Zealand Journal of Ecology (1998) 22(1): 65-70 ©New Zealand Ecological Society However, if buffer zones do not reduce lagomorph abundance and consequently chick predation, there is a danger from relaxation of conventional predator control measures which could potentially increase rates of predation on chicks. In addition, increased predation on chicks may result if buffer zones actually inc...
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