Effects of social behaviour on the spatial distribution of sheep grazing a complex vegetation mosaic

Sibbald, A. R.; Oom, Sander P.; Hooper, R. J.; Anderson, Roslyn M.

doi:10.1016/j.applanim.2008.06.007

Cited by 20 publications

(18 citation statements)

References 22 publications

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“…Although such dynamics may be not completely unknown to field biologists, this is, to our knowledge, the first quantitative study of a large group of social herbivores in a wellcontrolled homogeneous feeding environment. By using homogeneous pastures, we minimize as much as possible the effect of environment heterogeneity (44). Direct predation disturbances that may be invoked to explain increases in group density (12,13,45) are also ruled out in this context.…”

Section: Discussionmentioning

confidence: 99%

Intermittent collective dynamics emerge from conflicting imperatives in sheep herds

Ginelli

Peruani

Pillot

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

148

136

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Among the many fascinating examples of collective behavior exhibited by animal groups, some species are known to alternate slow group dispersion in space with rapid aggregation phenomena induced by a sudden behavioral shift at the individual level. We study this phenomenon quantitatively in large groups of grazing Merino sheep under controlled experimental conditions. Our analysis reveals strongly intermittent collective dynamics consisting of fast, avalanche-like regrouping events distributed on all experimentally accessible scales. As a proof of principle, we introduce an agent-based model with individual behavioral shifts, which we show to account faithfully for all collective properties observed. This offers, in turn, an insight on the individual stimulus/ response functions that can generate such intermittent behavior. In particular, the intensity of sheep allelomimetic behavior plays a key role in the group's ability to increase the per capita grazing surface while minimizing the time needed to regroup into a tightly packed configuration. We conclude that the emergent behavior reported probably arises from the necessity to balance two conflicting imperatives: (i) the exploration of foraging space by individuals and (ii) the protection from predators offered by being part of large, cohesive groups. We discuss our results in the context of the current debate about criticality in biology.sheep herds | collective behavior | self-organization | computational modeling | Allelomimetism T he social interactions and behavioral mechanisms involved in the coordination of collective movements in animal groups largely determine the animals' ability to display adapted responses when they face challenges, such as finding, efficiently, food sources (1-4) or safe resting places (5-7) or avoiding predators (8-13). Thus, the diversity of collective motion patterns observed in groupliving species reflects the multiple forms of interactions individuals use for coordinating their behavioral actions (14,15). Deciphering these interactions, their relation with the patterns emerging at the collective level, and their connections with the physiological and ecological constraints peculiar to each group-living species is crucial to understanding the evolution of collective phenomena in biological systems (16-18). So far, only a handful of quantitative datasets have been gathered for large animal groups (19-21). Most of them have focused on elementary cases where the prevailing biological imperative seems to be group cohesion, either to gain protection from potential predators, such as for the spontaneous collective motion exhibited by starling flocks (19,22) and some fish schools (23-25), or for reproductive purposes, as in swarms of midges (21,26).One important and, so far, often neglected aspect of collective motion is the existence of individual-level behavioral shifts, which, in turn, may trigger a transition at the collective level. For instance, in many species of fish, groups regularly alternate between a swarming state, in wh...

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Section: Discussionmentioning

confidence: 99%

Intermittent collective dynamics emerge from conflicting imperatives in sheep herds

Ginelli

Peruani

Pillot

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

148

136

View full text Add to dashboard Cite

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“…Therefore, the indices (PIG, IMP and IGP) determined by means of multivariate regression were important, especially in economic terms, as regions with higher GDP and a larger number of people tend to demand more products of animal origin (Sibbald al et al 2008).…”

Section: Univariate Approachmentioning

confidence: 99%

“…The successful production of small ruminants also depends on socioeconomic factors, because the higher the population, gross domestic product and the area, greater the demand for animal products and production also increases in adjacent areas (Hewitson et al 2007, Sibbald et al 2008.…”

Section: Introductionmentioning

confidence: 99%

Spatialization of climate, physical and socioeconomic factors that affect the dairy goat production in Brazil and their impact on animal breeding decisions

et al. 2012

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1073 em melhoramento animal.] O Brasil possui diversidade edafoclimática e realidades socioeconômicas e políticas distintas. Isto contribui para diferenciar as regiões polí-tico administrativas do país. Objetivou-se espacializar os fatores ϐísicos, climáticos e socioeconômicos que melhor discriminam a produção de caprinos leiteiros no Brasil. Foram analisados índice de produção de leite por cabra; ín-dice de produção de caprinos; índice de produção de leite, amplitude da temperatura; temperatura média; precipitação; índice normalizado de diferença vegetativa; umidade relativa do ar; altitude; estabelecimentos agropecuários; estabelecimentos com pastagem nativa; estabelecimentos com pastagens de boa qualidade; estabelecimentos com recursos hídricos; estabelecimentos que recebem orientação técnica; estabelecimentos de agricultura familiar; estabelecimentos de agricultura não familiar e índice de desenvolvimento humano. Brazil has high climate, soil and environmental diversity, as well as distinct socioeconomic and political realities, what results in differences among the political administrative regions of the country. The objective of this study was to determine spatial distribution of the physical, climatic and socioeconomic aspects that best characterize the production of dairy goats in Brazil. Production indices of milk per goat, goat production, milk production, as well as temperature range, mean temperature, precipitation, normalized difference vegetation index, relative humidity, altitude, agricultural farms; farms with native pasture, farms with good quality pasture, farms with water resources, farms that receive technical guidance, family farming properties, non-familiar farms and the human development index were evaluated. The multivariate analyses were carried out to spatialize climatic, physical and socioeconomic variables and so differenciate the Brazilian States and Regions. The highest yields of milk and goat production were observed in the Northeast. The Southeast Region had the second highest production of milk, followed by the South, Midwest and North. Multivariate analysis revealed distinctions between clusters of political-administrative regions of Brazil. The climatic variables were most important to discriminate between regions of Brazil. Therefore, it is necessary to implement animal breeding programs to meet the needs of each region.

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“…Sheep show strong social attraction behaviour and are more likely to move towards each other in order to forage the same patch (Dumont and Boissy, 2000;Sibbald et al, 2008) and show reluctance to move away from a group in order to feed (Sibbald et al, 2006). If food is scarce, individuals can be expected to spend a greater amount of time further away from each other and show -E-mail: rfreire@csu.edu.au increased movement and less social cohesion.…”

Section: Introductionmentioning

confidence: 99%

“…Domestic sheep are a highly social species that normally graze on heterogenous pasture (Penning et al, 1991) and their spatial distribution pattern is influenced by a number of factors (Arnold and Maller, 1985;Michelena et al, 2008;Sibbald et al, 2008). Sheep show strong social attraction behaviour and are more likely to move towards each other in order to forage the same patch (Dumont and Boissy, 2000;Sibbald et al, 2008) and show reluctance to move away from a group in order to feed (Sibbald et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Spatial distribution patterns of sheep following manipulation of feeding motivation and food availability

Freire

Swain

Friend

2012

Animal

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We hypothesised that (i) increased feeding motivation will cause sheep to move further apart as a result of individuals trying to find food and (ii) in conditions of high food availability, sheep will move less and show greater social attraction. The effects of both feeding motivation and food availability on spatial distribution was examined in eight groups of food-deprived (high feeding motivation) and satiated (low feeding motivation) sheep in good or poor food resource plots in a 2 3 2 design. Distance travelled was assessed using Global Positioning System collars, grazing time using scan sampling and social cohesion using proximity collars that record the number and duration of encounters within 4 m. Food-deprived sheep in the good-resource plots grazed the most, whereas satiated sheep in the poor-resource plots grazed the least (P 5 0.004). Food deprivation had no significant effect on the number or duration of encounters and feeding motivation appeared to have little effect on spatial distribution. Contrary to expectation, sheep had more encounters (P 5 0.04) of a longer total duration (P 5 0.02) in poor-resource plots than in good-resource plots, indicating that sheep were showing more social cohesion if food was scarce. Our findings suggest that when food is scarce, animals may come together in an attempt to share information on food availability. However, when a highly preferred food is abundant and well dispersed, they may move apart in order to maximise the intake. It is concluded that the particular details of our experiment, namely the even distribution or absence of a highly preferred food, affected spatial distribution patterns as sheep tried to find this food and maximise the intake.

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Effects of social behaviour on the spatial distribution of sheep grazing a complex vegetation mosaic

Cited by 20 publications

References 22 publications

Intermittent collective dynamics emerge from conflicting imperatives in sheep herds

Intermittent collective dynamics emerge from conflicting imperatives in sheep herds

Spatialization of climate, physical and socioeconomic factors that affect the dairy goat production in Brazil and their impact on animal breeding decisions

Spatial distribution patterns of sheep following manipulation of feeding motivation and food availability

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