Shape of the Interference Function in a Foraging Vertebrate

Stillman, Richard A.; Goss‐Custard, J. D.; Clarke, Ralph T.; Durell, S. E. A. Le V. Dit

doi:10.2307/5679

Cited by 70 publications

(86 citation statements)

References 22 publications

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“…instantaneous predation rate in relation to prey density (Holling 1959), have direct consequences for the understanding of ecological processes at the individual level, such as the role of dominance and interference on foraging efficiency (Goss-Custard et al 1984, Stillman et al 1996, Norris and Johnstone 1998, and to evaluate the role of these individual differences at the population level (Rubenstein 1981, Goss-Custard et al 1995, Piersma et al 1995. There are several mechanisms that can generate the various functional responses, particularly the asymptotic part: the competition between handling and searching for a prey, but also the interference between harvesting food and the velocity of the animal, or the competition between cropping and processing food (see Spalinger and Hobbs 1992 for the theoretical approach on herbivores).…”

Section: H Fritz D Durant and M Guillemain Cnrs-upr 1934 Centrementioning

confidence: 99%

Shape and sources of variations of the functional response of wildfowl: an experiment with mallards, Anas platyrhynchos

Fritz¹,

Durant²,

Guillemain³

2001

Oikos

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Understanding the variations of the functional response of an organism, i.e. the predation rate in relation to prey density, is necessary to understand the interactions between the animal and its food supply. This has received little attention in dabbling ducks so we investigated experimentally the shape of the functional response of mallard feeding on poultry pellets, and assessed the influence of several factors such as the size of food items, sex or individual performance on this functional response. Individual differences in intake rate are of crucial importance in group or gregarious foraging species. We used two approaches of the functional response: 1) the relation between feeding rate (pellets/s) and pellet densities (pellets/m 2 ), and 2) the relationship between instantaneous intake rate (g/s) and biomass density (g/m 2 ). For both approaches, we found that the Type II functional response gave better estimates than a Type I linear functional response but explained only a third of the variance. Our results show that pellet size has a large effect on instantaneous intake rate. The comparison of the functional response parameters suggest that handling time per prey may not reflect the real constraints on intake rate, but that handling time per gram ingested may be more appropriate to integrate the effect of item size in the functional response. We then discuss the possible mechanisms involved. We also found individual variations in the functional response for each of the experiments, with some consistency in the hierarchy regarding feeding efficiency. We did not find any differences between males and females. Our results provide an evaluation of individual variations in intake rate in interference-free conditions, which has rarely been done, and call for more controlled experiments to allow a finer understanding of the mechanisms of food acquisition in dabbling ducks.

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Section: H Fritz D Durant and M Guillemain Cnrs-upr 1934 Centrementioning

confidence: 99%

Shape and sources of variations of the functional response of wildfowl: an experiment with mallards, Anas platyrhynchos

Fritz¹,

Durant²,

Guillemain³

2001

Oikos

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“…This could be due to more interference between flock members in larger groups. Larger flocks may be more likely to disrupt prey and cause a temporary reduction in amphipod availability due to the avoidance response of the prey (Goss-Custard 1980;Stillman et al 1996;Triplet et al 1999). This type of temporary reduction in prey is particularly likely for highly mobile prey such as amphipods 0.037* that can quickly seek cover within the sand or within beach debris in the presence of predators (Dolah 1978;Williams 1995).…”

Section: Flock Size and Feeding Interferencementioning

confidence: 98%

The effects of human presence, flock size and prey density on shorebird foraging rates

Yasué

2005

J Ethol

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Animals may alter their foraging behaviour in the presence of humans because they perceive humans as potential predators. In this study I determined whether people caused shorebirds to reduce feeding rates at a stopover site in coastal British Columbia, Canada. I controlled for prey density and flock size because these variables may influence both the foraging rates as well as the effect of human disturbance on feeding efficiency. Semipalmated plovers decreased feeding rates when there were more people on the beach (multiple regression: F 1,15 = 5.86, b = 0.59, P = 0.029, R 2 = 37.6%). For least sandpipers, the effect of human densities on feeding rates depended on flock size (F 1,21 = 5.97, P = 0.023) and amphipod availability (F 1,21 = 4.98, P = 0.037). This study demonstrated the importance of measuring subtle behavioural changes in foraging rates along with key ecological variables in order to assess the true impact of human disturbance on migratory shorebirds.

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“…Simulations consider values of m in the range 0-2 < m < 0-6. Equations 3 and 4 assume that the coefficient of interference is constant; however, it may vary with consumer density (Hassell & Varley 1969;Beddington 1975;Hassell 1978;Stillman et al 1996) and resource density (Dolman 1995; Moody & Ruxton, in press).…”

Section: Simulation Model Of Spatial Depletionmentioning

confidence: 98%

Spatial Patterns of Depletion Imposed by Foraging Vertebrates: Theory, Review and Meta-Analysis

Dolman¹,

Sutherland²

1997

The Journal of Animal Ecology

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Shape of the Interference Function in a Foraging Vertebrate

Cited by 70 publications

References 22 publications

Shape and sources of variations of the functional response of wildfowl: an experiment with mallards, Anas platyrhynchos

Shape and sources of variations of the functional response of wildfowl: an experiment with mallards, Anas platyrhynchos

The effects of human presence, flock size and prey density on shorebird foraging rates

Spatial Patterns of Depletion Imposed by Foraging Vertebrates: Theory, Review and Meta-Analysis

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