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Collective decision making and social interaction rules in mixed-species flocks of songbirds.

Farine DR, Aplin LM, Garroway CJ, Mann RP, Sheldon BC - Anim Behav (2014)

Bottom Line: We found that species differed in their response to the distribution of conspecifics and heterospecifics across foraging patches.However, simulating decisions using the different rules, which reproduced our data well, suggested that the outcome of using different decision rules by each species resulted in qualitatively similar overall patterns of movement.This is likely to be important for maintaining coordinated behaviour across species, and to result in quick and adaptive flock responses to food resources that are patchily distributed in space and time.

View Article: PubMed Central - PubMed

Affiliation: Edward Grey Institute of Field Ornithology, Department of Zoology, Oxford, U.K. ; Department of Anthropology, University of California Davis, Davis, CA, U.S.A. ; Smithsonian Tropical Research Institute, Ancon, Panama.

ABSTRACT
Associations in mixed-species foraging groups are common in animals, yet have rarely been explored in the context of collective behaviour. Despite many investigations into the social and ecological conditions under which individuals should form groups, we still know little about the specific behavioural rules that individuals adopt in these contexts, or whether these can be generalized to heterospecifics. Here, we studied collective behaviour in flocks in a community of five species of woodland passerine birds. We adopted an automated data collection protocol, involving visits by RFID-tagged birds to feeding stations equipped with antennae, over two winters, recording 91 576 feeding events by 1904 individuals. We demonstrated highly synchronized feeding behaviour within patches, with birds moving towards areas of the patch with the largest proportion of the flock. Using a model of collective decision making, we then explored the underlying decision rule birds may be using when foraging in mixed-species flocks. The model tested whether birds used a different decision rule for conspecifics and heterospecifics, and whether the rules used by individuals of different species varied. We found that species differed in their response to the distribution of conspecifics and heterospecifics across foraging patches. However, simulating decisions using the different rules, which reproduced our data well, suggested that the outcome of using different decision rules by each species resulted in qualitatively similar overall patterns of movement. It is possible that the decision rules each species uses may be adjusted to variation in mean species abundance in order for individuals to maintain the same overall flock-level response. This is likely to be important for maintaining coordinated behaviour across species, and to result in quick and adaptive flock responses to food resources that are patchily distributed in space and time.

No MeSH data available.


Related in: MedlinePlus

Overview of the relationship between the proportion of individuals on a site and (a) the probability of that site being identified as good and (b) the probability of choosing that site in a two-site decision, under the decision-making model fitted in this paper. Functions are shown for different values of parameters s and k in the model by Arganda et al. (2012). Higher values of s form a stronger threshold value, whereas lower values of s result in responses similar to linear gradients. Lower values of k shift the probability curve left, and create a larger region of indifference between two sites (in this case creating an area with an equal probability of choosing either site at proportions from 0.3 to 0.7). Values of a > 1 result in a higher penalty for low-density sites. One important feature of this model is that the probability of picking a site with no individuals is never 0.
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fig2: Overview of the relationship between the proportion of individuals on a site and (a) the probability of that site being identified as good and (b) the probability of choosing that site in a two-site decision, under the decision-making model fitted in this paper. Functions are shown for different values of parameters s and k in the model by Arganda et al. (2012). Higher values of s form a stronger threshold value, whereas lower values of s result in responses similar to linear gradients. Lower values of k shift the probability curve left, and create a larger region of indifference between two sites (in this case creating an area with an equal probability of choosing either site at proportions from 0.3 to 0.7). Values of a > 1 result in a higher penalty for low-density sites. One important feature of this model is that the probability of picking a site with no individuals is never 0.

Mentions: In this model, individuals make decisions based on Bayesian estimation, using information generated by others. The derivation of the model introduces a parameter s which equates to an individual's judgement that others make a ‘good choice’ s times more often than a bad choice. Thus, if B is public or social information, then s can be considered the rate of social information use. A value of s = 1 suggests no socially mediated response, or an equal probability of picking any feeder regardless of where individuals are located (P(Xi) = 0.25 for all four feeders at all times). When s > 1, individual decisions are influenced by the distribution of others within the patch (Fig. 2). At small values of s, the probability curve is almost linear with only a small increase in the probability of choosing a busy feeder over an empty feeder (see Fig. 2). At larger values of s, this curve becomes sigmoidal; therefore the probability of choosing empty feeders approaches 0 and the probability of choosing busy feeders approaches 1.


Collective decision making and social interaction rules in mixed-species flocks of songbirds.

Farine DR, Aplin LM, Garroway CJ, Mann RP, Sheldon BC - Anim Behav (2014)

Overview of the relationship between the proportion of individuals on a site and (a) the probability of that site being identified as good and (b) the probability of choosing that site in a two-site decision, under the decision-making model fitted in this paper. Functions are shown for different values of parameters s and k in the model by Arganda et al. (2012). Higher values of s form a stronger threshold value, whereas lower values of s result in responses similar to linear gradients. Lower values of k shift the probability curve left, and create a larger region of indifference between two sites (in this case creating an area with an equal probability of choosing either site at proportions from 0.3 to 0.7). Values of a > 1 result in a higher penalty for low-density sites. One important feature of this model is that the probability of picking a site with no individuals is never 0.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4157325&req=5

fig2: Overview of the relationship between the proportion of individuals on a site and (a) the probability of that site being identified as good and (b) the probability of choosing that site in a two-site decision, under the decision-making model fitted in this paper. Functions are shown for different values of parameters s and k in the model by Arganda et al. (2012). Higher values of s form a stronger threshold value, whereas lower values of s result in responses similar to linear gradients. Lower values of k shift the probability curve left, and create a larger region of indifference between two sites (in this case creating an area with an equal probability of choosing either site at proportions from 0.3 to 0.7). Values of a > 1 result in a higher penalty for low-density sites. One important feature of this model is that the probability of picking a site with no individuals is never 0.
Mentions: In this model, individuals make decisions based on Bayesian estimation, using information generated by others. The derivation of the model introduces a parameter s which equates to an individual's judgement that others make a ‘good choice’ s times more often than a bad choice. Thus, if B is public or social information, then s can be considered the rate of social information use. A value of s = 1 suggests no socially mediated response, or an equal probability of picking any feeder regardless of where individuals are located (P(Xi) = 0.25 for all four feeders at all times). When s > 1, individual decisions are influenced by the distribution of others within the patch (Fig. 2). At small values of s, the probability curve is almost linear with only a small increase in the probability of choosing a busy feeder over an empty feeder (see Fig. 2). At larger values of s, this curve becomes sigmoidal; therefore the probability of choosing empty feeders approaches 0 and the probability of choosing busy feeders approaches 1.

Bottom Line: We found that species differed in their response to the distribution of conspecifics and heterospecifics across foraging patches.However, simulating decisions using the different rules, which reproduced our data well, suggested that the outcome of using different decision rules by each species resulted in qualitatively similar overall patterns of movement.This is likely to be important for maintaining coordinated behaviour across species, and to result in quick and adaptive flock responses to food resources that are patchily distributed in space and time.

View Article: PubMed Central - PubMed

Affiliation: Edward Grey Institute of Field Ornithology, Department of Zoology, Oxford, U.K. ; Department of Anthropology, University of California Davis, Davis, CA, U.S.A. ; Smithsonian Tropical Research Institute, Ancon, Panama.

ABSTRACT
Associations in mixed-species foraging groups are common in animals, yet have rarely been explored in the context of collective behaviour. Despite many investigations into the social and ecological conditions under which individuals should form groups, we still know little about the specific behavioural rules that individuals adopt in these contexts, or whether these can be generalized to heterospecifics. Here, we studied collective behaviour in flocks in a community of five species of woodland passerine birds. We adopted an automated data collection protocol, involving visits by RFID-tagged birds to feeding stations equipped with antennae, over two winters, recording 91 576 feeding events by 1904 individuals. We demonstrated highly synchronized feeding behaviour within patches, with birds moving towards areas of the patch with the largest proportion of the flock. Using a model of collective decision making, we then explored the underlying decision rule birds may be using when foraging in mixed-species flocks. The model tested whether birds used a different decision rule for conspecifics and heterospecifics, and whether the rules used by individuals of different species varied. We found that species differed in their response to the distribution of conspecifics and heterospecifics across foraging patches. However, simulating decisions using the different rules, which reproduced our data well, suggested that the outcome of using different decision rules by each species resulted in qualitatively similar overall patterns of movement. It is possible that the decision rules each species uses may be adjusted to variation in mean species abundance in order for individuals to maintain the same overall flock-level response. This is likely to be important for maintaining coordinated behaviour across species, and to result in quick and adaptive flock responses to food resources that are patchily distributed in space and time.

No MeSH data available.


Related in: MedlinePlus