Search results for "foraging"
showing 10 items of 204 documents
Modeling sequential production: the migratory beekeeper case
2018
This paper formalizes a bio-economic model of migratory beekeeping activities, during the annual production cycle, so as to discern the optimal sequence of foraging sites for migratory beekeepers; it then proceeds to empirically verify the model via a case study. The model assumes that the apiary farm produces three marketable outputs under conditions of certainty with disjunctive resources at the sites. In particular, honey, commercial pollination services and nucleus colonies are produced sequentially at foraging sites throughout the year. The model determines a migratory beekeeperâs revenues, variable costs, gross income from each sequence of foraging sites under the constraint that th…
Functional implications of the staminal lever mechanism in Salvia cyclostegia (Lamiaceae)
2011
Flower morphology and inflorescence architecture affect pollinator foraging behaviour and thereby influence the process of pollination and the reproductive success of plants. This study explored possible ecological functions of the lever-like stamens and the floral design in Salvia cyclostegia.Flower construction was experimentally manipulated by removing either the lower lever arms or the upper fertile thecae of the two stamens from a flower. The two types of manipulated individuals were intermixed with the control ones and randomly distributed in the population.Removing the sterile lower lever arms significantly reduced handling time per flower of the main pollinator, Bombus personatus. I…
First Record of Eurasian Spoonbills Platalea leucorodia feeding on Branchiopoda in a temporary wetland
2020
The diet of the Eurasian Spoonbill Platalea leucorodia is poorly documented with only the most common prey groups known, namely small fishes, amphibians, reptiles, crustaceans, molluscs, worms, leeches and plant material. Here, the first observations of three small crustaceans, Branchiopoda Triops cancriformis (Notostraca), Chirocephalus diaphanus (Anostraca), and Cyzicus tetracerus (Spinicaudata) are documented as prey of the Eurasian Spoonbill in a temporary wetland near the San Teodoro salt pan (Marsala, western Sicily). These observations provide a new insight into the foraging ecology of the species, showing its extreme opportunism in targeting small prey when feeding in a temporary we…
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…
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…
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…
Vigilance and food intake rate in paired and solitary Zenaida DovesZenaida aurita
2011
We quantified vigilance during feeding in the Zenaida Dove Zenaida aurita, a tropical species with stable pair-bonds and year-round territoriality. Both males and females decreased the proportion of time spent vigilant by 30% when feeding with their partner compared with when feeding alone. This reduction was achieved through increasing the length of inter-scan duration, while scan duration remained constant. No evidence was found for coordination of vigilance between pair members. The equal investment in vigilance by male and female Zenaida Doves might be related to the mutual benefits of long-term pair-bonding.
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…
Parasite-induced alteration of plastic response to predation threat: increased refuge use but lower food intake in Gammarus pulex infected with the a…
2014
6 pages; International audience; Larvae of many trophically-transmitted parasites alter the behaviour of their intermediate host in ways that increase their probability of transmission to the next host in their life cycle. Before reaching a stage that is infective to the next host, parasite larvae may develop through several larval stages in the intermediate host that are not infective to the definitive host. Early predation at these stages results in parasite death, and it has recently been shown that non-infective larvae of some helminths decrease such risk by enhancing the anti-predator defences of the host, including decreased activity and increased sheltering. However, these behavioura…
Effets de la variabilité inter-individuelles et des interactions intra-guildes sur les stratégies d'approvisionnement de carabes consommateurs de gra…
2017
Making a choice requires, implicitly, an investment of time in one behaviour at the expense of an investment in another. Being choosy would increase the risk of losing many food item opportunities to competitors, and is directly in conflict with other essential tasks such as predator avoidance. Individuals are thus expected to adjust their level of choosiness in response to the competition and predation context. The available behavioural ecological theory and the empirical ecology of carabids would suggest that competition and predation interference induces changes in the foraging behaviour of carabid individuals. Carabids typically operate within communities in which competition and predat…