Mechanisms of group-hunting in vertebrates

Group-hunting is ubiquitous across animal taxa and has received considerable attention in the context of its functions. By contrast much less is known about the mechanisms by which grouping predators hunt their prey. This is primarily due to a lack of experimental manipulation alongside logistical difficulties quantifying the behaviour of multiple predators at high spatiotemporal resolution as they search, select, and capture wild prey. However, the use of new remote-sensing technologies and a broadening of the focal taxa beyond apex predators provides researchers with a great opportunity to discern accurately how multiple predators hunt together and not just whether doing so provides hunters with a per capita benefit. We incorporate many ideas from collective behaviour and locomotion throughout this review to make testable predictions for future researchers and pay particular attention to the role that computer simulation can play in a feedback loop with empirical data collection. Our review of the literature showed that the breadth of predator:prey size ratios among the taxa that can be considered to hunt as a group is very large (<10⁰ to >10²). We therefore synthesised the literature with respect to these predator:prey ratios and found that they promoted different hunting mechanisms. Additionally, these different hunting mechanisms are also related to particular stages of the hunt (search, selection, capture) and thus we structure our review in accordance with these two factors (stage of the hunt and predator:prey size ratio). We identify several novel group-hunting mechanisms which are largely untested, particularly under field conditions, and we also highlight a range of potential study organisms that are amenable to experimental testing of these mechanisms in connection with tracking technology. We believe that a combination of new hypotheses, study systems and methodological approaches should help push the field of group-hunting in new directions.     

Livestock Acquisitions Dynamics in Nomadic Pastoralist Herd Demography: A Case Study Among Ngisonyoka Herders of South Turkana, Kenya

Despite the attention given to social relations in the pastoral literature, the role of livestock acquisitions—additions of livestock to herds through bridewealth, exchanges, gifts, payments, and begging (requests)—in herd build up has usually been assumed to be relatively minor compared to births and relevant mostly when the need for rebuilding arises after major losses. This study is based on an unusual set of data—the reproductive histories of the female cattle, camels, and goats and sheep of 13 Ngisonyoka Turkana nomadic herders in northwestern Kenya, collected in 1987. The article reports on the means by which mothers were added to the herd and how these changed through time. The results suggest that for this population in the late 1970s and 1980s, acquisitions were not merely relevant when disaster struck, but instead were a continuously important component of herd management. The results demonstrate the crucial role of social networks in the survival of Ngisonyoka pastoralists in their non-equilibrial ecosystem. Social exchanges, such as bridewealth, provide a resource security well suited to the challenges of coping with such unpredictable environments. Researchers and policymakers are urged to make efforts to support such indigenous networks if they want nomadic pastoralists to continue their effective use of arid, marginal lands.

Theories of Nomadic Movement: A New Theoretical Approach for Understanding the Movement Decisions of Nenets and Komi Reindeer Herders

It is known that the relationship between humans and their animals is important for understanding many aspects of nomadic pastoralist systems, including nomadic movement. However, to date, these complex human–animal relations have not been analyzed in a way that has led to an explanatory model of nomadic movement capable of producing testable hypotheses. Based on ethnographic material collected amongst Komi and Nenets nomadic reindeer herders of the Russian Arctic, we argue that nomadic movements can be best understood as a product of the interplay that exists between animal behaviour and the herders’ skilful actions to (a) maintain herd cohesion and (b) avoid hazards, whilst deploying the minimum amount of resources (i.e., human/animal effort and use of equipment) on rounding up the herd, stopping and turning it. Ecological factors affect movement through their influence on animal behaviour, whereas non-ecological factors do so by influencing the herders’ skilful actions. We demonstrate that, based on these assumptions, it is possible to build a testable model explaining the movement of some nomadic groups.

Courtship herding in the fiddler crab <Emphasis Type="Italic">Uca elegans</Emphasis>

Male and female animals are not always complicit during reproduction, giving rise to coercion. One example of a system that is assumed to involve sexual coercion is the mate herding behaviour of fiddler crabs: males push females towards the home burrow with the goal of forcing copulation at the burrow entrance. We recorded and analysed in detail the courtship behaviour of a North Australian species of fiddler crab Uca elegans. Courtship was composed of four main phases: broadcast waving, outward run, herding and at burrow display. During interactions males produced claw-waving displays which were directed posteriorly towards the female and which varied in timing and structure depending on the courtship phase. We suggest that courtship herding in U. elegans is driven primarily by mate choice for the following reasons, (1) females can evade herding, (2) no other reproductive strategies were observed, (3) males broadcast their presence and accompany courtship with conspicuous claw waves, and (4) the behaviour ends with the female leading the male into the home burrow. As an alternative function for herding in U. elegans we suggest that the behaviour represents a form of courtship guiding, in which males direct complicit females to the correct home burrow.     

Reconsidering the Role of Absentee Herd Owners: A View from Mongolia

Since the privatization of livestock in 1992, rates of absentee ownership of livestock have increased sharply in Mongolia. Unlike other documented instances of absentee herding in pastoral societies, absentee herd ownership has few detrimental ecological or social impacts in Mongolia. Rather, the relationship between absentee herd owners and herders may be viewed as a revitalized institution, with links to customary patterns of urban-rural exchange, emerging to meet the needs of both herders and town-dwellers during the transition from a socialist planned economy to a free market economy. Absentee herding in Mongolia differs from absentee and contract herding accounts from Africa and the Middle East in its continuing emphasis on subsistence rather than speculative investment and accumulation. Other important distinctions include: (1) absentee owners and herders are usually kin or friends; (2) herders tend their own private herds in addition to absenteeowned animals;(3)few ethnic, caste, or class differences existbetween herders and absentee herd owners; and (4) herders from all wealth strata tend absentee-owned animals. Policies to restrict or regulate absentee livestock ownership must be carefully considered in the Mongolian context, making clear distinctions between informal, mutually beneficial subsistence-driven arrangements among kin and friends, and more formal investment-driven contracts between businesses or investors and herders.     

Herding,social influence and economic decision-making: socio-psychological and neuroscientific analyses

Typically, modern economics has steered away from the analysis of sociological and psychological factors and has focused on narrow behavioural assumptions in which expectations are formed on the basis of mathematical algorithms. Blending together ideas from the social and behavioural sciences, this paper argues that the behavioural approach adopted in most economic analysis, in its neglect of sociological and psychological forces and its simplistically dichotomous categorization of behaviour as either rational or not rational, is too narrow and stark. Behaviour may reflect an interaction of cognitive and emotional factors and this can be captured more effectively using an approach that focuses on the interplay of different decision-making systems. In understanding the mechanisms affecting economic and financial decision-making, an interdisciplinary approach is needed which incorporates ideas from a range of disciplines including sociology, economic psychology, evolutionary biology and neuroeconomics.     

藏香猪放牧对滇西北高原湿地土壤CO2通量的影响

高原湿地是生态系统中重要的碳汇。土壤CO_2通量作为高原湿地生态系统碳收支的重要组成部分,碳的释放对区域碳平衡发挥着重要的作用。藏香猪放牧是我国高海拔藏区一种特有的放牧方式,是导致高原湿地土壤退化的重要干扰因素之一,并影响着土壤CO_2通量的变化。采用土壤CO_2通量自动测量系统(LI-8100A,LI-COR,USA),分别在不同季节对滇西北布伦、哈木谷、伊拉草原上藏香猪干扰和对照(非干扰土壤)CO_2通量变化进行监测,研究发现,藏香猪干扰型放牧降低了土壤CO_2排放通量,且表现出明显的日波动变化特征。相比旱季,雨季不同放牧方式影响下的土壤CO_2通量差异性更为明显,其中布伦、哈木谷、伊拉草原较对照分别降低了70.4%、87.5%、60.7%。CO_2排放通量与土壤理化性状及植物生物量的回归分析表明,对照样地的土壤容重、孔隙度、pH、总活性碳、植物生物量与土壤CO_2通量具有显著的相关性(P0.01)。通过植物-土壤指数(plant-soil index,PSI)分析了藏香猪干扰型放牧对高原湿地的影响,总体来看,对照样地中土壤CO_2通量与PSI之间具有较好的线性关系,可以用来很好的预测未来高原湿地土壤CO_2通量的变化。该研究结果不仅有效估算了强干扰放牧影响下的高原湿地土壤碳排放量,而且为加强藏香猪放牧的科学管理,高原湿地生态系统的保护、恢复及重建提供了理论支持。     

Scale Dependency and the “Marginal” Value of Labor

Human Ecology - While there is a general assumption that labor has a positive effect on pastoral production, studies that have tried to quantify this relationship have found no effects. This is...     

Indicating human-environmental system properties: Case study northern Fenno-Scandinavian reindeer herding

According to the contemporary ecosystem approach, integrated management of natural resources recognizes that humans, with their cultural diversity, are an integral component of many ecosystems. Therefore, the linkages of human actions with their environment have to be assessed in an integrative manner. Appropriate models and indicators, data and information for human and environmental systems are needed as well as suitable linkages between the specific components. In this paper, an indicator framework for the analysis and assessment of complex human-environmental systems is presented. An example application from a research project dealing with the development of sustainable management strategies for the husbandry of semi-domesticated reindeer in northern Fenno-Scandinavia illustrates the potentials and limitations of this framework. The concept and indicators of ecological integrity are used to assess the impacts of reindeer herding on the natural environment. Human well-being is evaluated with indicators for social and economic welfare. In conjunction with three scenarios, associated with varying land use patterns and land use priorities, the relevance of the particular components for a sustainable resource management in the case study area was estimated and recommendations to management authorities could be given.     

Modification of instinctive herding dog behavior using reinforcement and punishment

Abstract

“Instinctive” behavior may be modified using operant techniques. We report here on a field study of training herding dogs in which reinforcers and punishers were used by owners, who were themselves being trained to control their dogs. Access to sheep was assumed to be a primary reinforcer for herding dogs. While blocking their access was aversive to them. Over several months, the number of blocking and access actions by the human were scored during the training of seven naïve herding dogs. We found that rates of punishment by blocking the dog's access to sheep or by stopping the dog occurred at higher levels than positive reinforcement from access or verbal praise. While positive reinforcement can be used exclusively for the training of certain behaviors, it is suggested that in the context of instinctive motor patterns, negative reinforcement and punishment may be desirable and necessary additions to positive reinforcement techniques.