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A test of the producer-scrounger foraging game in captive flocks of spice finches,Loncbura punctulata 总被引:2,自引:0,他引:2
Luc-Alain Giraldeau Catherine Soos Guy Beauchamp 《Behavioral ecology and sociobiology》1994,34(4):251-256
Group foraging allows the co-existence of a strategy (producer) that involves searching for food, and its alternative (scrounger) exploiting the food of the producer. The use of producer and scrounger strategies has been modelled as an alternative-option scramble which assumes strong negative frequency-dependence of the scrounger's pay-offs. We tested this assumption in a flock feeding situation by manipulating the proportion of scroungers in flocks of spice finches, Lonchura punctulata. In a first experiment we found that: (1) the food intake of scroungers, and to a lesser extent producers, was negatively affected by an increase in the proportion of scroungers; (2) the food intake of producers and scroungers was equal when the proportion of scroungers was small, suggesting that producers, who exploited 35.4% of their patches by scrounging were opportunistically adjusting their use of the strategies until the pay-offs equalized. In a second experiment we tested whether finches could vary their use of the two strategies in response to changes in foraging conditions brought about by an increase in the cost of producing. As predicted by the game, finches reduced their use of the producer strategy and increased their use of the scrounger strategy when the cost of producing increased. These results suggest that spice finches can alter their allocation to each foraging alternative by experience and that the producer-scrounger game is a realistic model for predicting group foraging decisions.
Correspondence to: L.-A. Giraldeau 相似文献
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Maryse Barrette Guy Boivin Jacques Brodeur Luc-Alain Giraldeau 《Behavioral ecology and sociobiology》2010,64(4):593-598
Models of prey choice in depleting patches predict an expanding specialist strategy: Animals should start as specialists on
the most profitable prey and then at some point during patch exploitation switch to a generalist foraging strategy. When patch
residence time is long, the switch to a generalist diet is predicted to occur earlier than when patch residence time is short.
We tested these predictions under laboratory conditions using female parasitoids (Aphidius colemani) exploiting patches of mixed instars aphid hosts (Myzus persicae, L1 and L4). The duration of patch exploitation was manipulated by changing travel time between patches. As predicted, patch
residence times increase with travel time between patches. Our results provide empirical support for the expanding specialist
prediction: Parasitoid females specialized initially on the more profitable hosts (L4), and as the patch depleted, they switched
to a generalist diet by accepting more frequently the less profitable hosts (L1). The point at which they switched from specialist
to generalist occurred later when travel times and hence patch residence times were short. By affecting the patch exploitation
strategy, travel time also determines the composition of hosts left behind, the “giving up composition.” The change in the
relative density of remaining host types alters aphid populations’ age structure. 相似文献
3.
Vicarious sampling: the use of personal and public information by starlings foraging in a simple patchy environment 总被引:6,自引:0,他引:6
Group foragers may be able to assess patch quality more efficiently by paying attention to the sampling activities of conspecifics
foraging in the same patch. In a previous field experiment, we showed that starlings foraging on patches of hidden food could
use the successful foraging activities of others to help them assess patch quality. In order to determine whether a starling
could also use another individual’s lack of foraging success to assess and depart from empty patches more quickly, we carried
out two experimental studies which compared the behaviour of captive starlings sampling artificial patches both when alone
and when in pairs. Solitary starlings were first trained to assess patch quality in our experimental two-patch system, and
were then tested on an empty patch both alone and with two types of partner bird. One partner sampled very few holes and thus
provided a low amount of public information; the other sampled numerous holes and thus provided a high amount of public information.
In experiment 1, we found no evidence of vicarious sampling. Subjects sampled a similar number of empty holes when alone as
when with the low and high information partners; thus they continued to rely on their own personal information to make their
patch departure decisions. In experiment 2, we modified the experimental patches, increasing the ease with which a bird could
watch another’s sampling activities, and increasing the difficulty of acquiring accurate personal sampling information. This
time, subjects apparently did use public information, sampling fewer empty holes before departure when with the high-information
partner than when with the low-information partner, and sampling fewer holes when with the low-information partner than when
alone. We suggest that the degree to which personal and public information are used is likely to depend both on a forager’s
ability to remember where it has already sampled and on the type of environment in which foraging takes place.
Received: 31 January 1995/Accepted after revision: 11 September 1995 相似文献
4.
The effect of dominance hierarchy on the use of alternative foraging tactics: a phenotype-limited producing-scrounging game 总被引:2,自引:0,他引:2
Group living is thought to be advantageous for animals, though it also creates opportunities for exploitation. Using food
discovered by others can be described as a producer-scrounger, frequency-dependent game. In the game, scroungers (parasitic
individuals) do better than producers (food finders) when scroungers are rare in the group, but they do worse when scroungers
are common. When the individuals' payoffs do not depend on their phenotype (i.e. a symmetric game), this strong negative frequency
dependence leads to a mixed stable solution where both alternatives obtain equal payoffs. Here, we address the question of
how differences in social status in a dominance hierarchy influence the individuals' decision to play producer or scrounger
in small foraging groups. We model explicitly the food intake rate of each individual in a dominance-structured foraging group,
then calculate the Nash equilibrium for them. Our model predicts that only strong differences in competitive ability will
influence the use of producing or scrounging tactics in small foraging groups; dominants will mainly play scrounger and subordinates
will mostly use producer. Since the differences in competitive ability of different-ranking individuals likely depend on the
economic defendability of food, our model provides a step towards the integration of social foraging and resource defence
theories.
Received: 30 July 1997 / Accepted after revision: 15 November 1997 相似文献
5.
Many animals share food, that is, to tolerate competitors at a defensible clump. Most accounts of resource sharing invoke
special evolutionary processes or ecological circumstances that reduce their generality. Surprisingly, the Hawk–Dove game
has been unable to address in a simple and general way why so many group foraging animals share food. We modify the Hawk–Dove
game by allowing a finder the opportunity of retaliating if joiners escalate and by considering the consequences of information
asymmetries concerning resource value among players. Introducing the first change, the retaliator strategy was sufficient
to predict widespread sharing in habitats where food clumps are of intermediate richness. When information asymmetry between
finder and joiner is created by allowing the quality of clumps to vary, we show that the conditions for sharing are even more
easily met and apply to a wider range of resource qualities. Our model therefore offers one of the most parsimonious and potentially
general evolutionary accounts of the origin of non-aggressive resource sharing. 相似文献
6.
When animals forage in groups, they can search for food themselves (producer tactic), or they can search for opportunities
to exploit the food discoveries of others (scrounger tactic). Both theoretical and empirical work have shown that group-level
use of these alternative tactics is influenced by environmental conditions including group size and food distribution, and
individual tactic use can be influenced by several measures of individual state, including body condition. Because body condition
has been shown to be heritable for various species, social foraging tactics may also be heritable. We looked for evidence
of heritability in social foraging tactic use in the zebra finch (Taeniopygia guttata) by testing whether: (1) natural variation in body condition correlates with tactic use, (2) there are family-related differences
in body condition, and (3) there are family-related differences in observed tactic use. Tactic use in the zebra finch was
significantly related to body condition; individuals with lower body condition scores had a significantly higher use of the
scrounger tactic as predicted from variance-sensitive producer–scrounger models. Body-condition scores differed significantly
between families, suggesting that this aspect of individual state may have a heritable component. Finally, we recorded significant
family-related differences in the use of producer and scrounger alternatives. These results are consistent with heritability
in observed tactic use resulting from an inheritance of individual state, in this case body condition, which itself influences
tactic use. Understanding how and why individuals differ in their use of alternative tactics is fundamental as it may provide
important insights into inter-individual variation in fitness. 相似文献
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