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The behavioural biology of chickens
Animal Behaviour 117 (2016) 1e2
Contents lists available at ScienceDirect
Animal Behaviour journal homepage: www.elsevier.com/locate/anbehav
Book Review The behavioural biology of chickens, Christine J. Nicol. Wallingford, U.K.: CABI (2015). Pp. 192. Price £75.00 hardback. The enormity in scale of numbers of chickens worldwide is astronomical. As the most popular global choice for meat, the number of meat chickens reared and killed in 2013 exceeded the number of humans alive on the planet by a scale of almost 10 to 1 (FAOStat, 2016). There are a lot of them, so it certainly makes sense to try to understand them. Several books written in the last few decades have included chicken behaviour and welfare to some extent (Appleby, Mench, & Hughes, 2004; Grandin & Deesing, 2013); however, most have focused principally on production systems and the welfare issues arising from these. While Nicol's book does include several chapters on production and welfare, the primary focus, and the key mark of difference for this book, is in its detail on the chicken's biology. In this book, Nicol, a world authority on chicken behaviour and welfare, explores the biology of this most popular of birds in such a clear, straight, and thoroughly engaging way that reading it is light work. This is most peculiar when one also considers the sheer volume of information that bursts out of every page. On reading it, one cannot help but marvel at just how underestimated the humble chicken is. Nicol opens her tour-de-force with a discussion of genetics and domestication in Chapter 1, where we are introduced to the changing ideas on chicken ancestry and domestication, the practices used in commercial breeding and the impacts of selective breeding programmes on the chicken's genome and behaviour. Chapter 2 on sensory biology makes light but thorough work of the dense literature on chicken vision, hearing, taste, olfaction and magnetoreception, leaving the reader with a clear sense of chicken perceptual abilities and limits, and the implications of these for their health and welfare. Chapter 3 continues apace, this time moving into the development of the avian brain, where we are led to understand how the evolving view of bird brains has brought us to a point where there is no solid argument against the possibility of chickens being capable of primary conscious experience. We have come a long way from the school of thought where birds were just another rung on the ladder to a massive, differentiated telencephalon. Nicol continues on to discuss epigenetic influences on embryonic development and brain lateralization ultimately leading to differences in behaviour in the birds as adults. This is fascinating, touching on the contrasting evidence supporting the alternative hypotheses that the mother has passive or active control of the environmental factors that may subsequently lead to alterations in the expression of genetic material in later life, and what the long-term consequences of this may be in terms of alterations in behaviour. The measurement of behaviour is one of the three key pillars of welfare assessment. The subject of animal welfare in relation to chickens in both of their commercial forms, the meatproducing broiler and the egg-laying hen, is one that has received http://dx.doi.org/10.1016/j.anbehav.2016.04.018 0003-3472
a great deal of both academic and public attention. The publication of Animal Machines (Harrison, 1964) raised the issue of welfare compromise as a consequence of agricultural intensification following World War II. Since the publication of Harrison's book, the number of chickens produced annually has increased more than five-fold (FAOStat, 2016). With year-on-year increases in demand for animal products, intensification is set to continue to escalate into the future (Delgado, Rosegrant, Steinfeld, Ehui, & Courbois, 1999; Kearney, 2010). In Chapter 4, Nicol turns to the study of behaviour as a means of understanding the underlying welfare state of an animal, the level of internal motivation it has to attain a resource or perform certain behaviours, and ultimately to understand what the bird itself considers to be its key priorities. This leads naturally into Chapter 5, where Nicol follows the idea of ‘behaviours that matter’ (Nicol, 2011), and are considered to be of relatively higher priority to the birds, to understand what factors can influence the performance of such behaviours within commercial systems, highlighting the large differences in daily activity budget and diversity in behavioural repertoires between broilers and laying hens. All chickens, regardless of their production type, are social animals. The nature and dynamics of their sociality depends on their life stage, the quantity and distribution of resources in the environment, and the seasons. In Chapter 6, Nicol turns to the social behaviour of chickens, discussing recognition and preferences by individuals, the overall social structure of a group and the spatiotemporal dynamics of social behaviour that allows a group to synchronize their individual behaviour patterns. In social groups demonstrating high levels of spatial or temporal clustering in behaviour, one might naturally consider the affiliative bonds between individuals, and investigate the extent to which they are capable of empathy for conspecifics; such factors have been shown to be of particular importance in human groups (Fan, Duncan, de Greck, & Northoff, 2011; Shamay-Tsoory, Ahron-Peretz, & Perry, 2009). Recent studies from within Nicol's research lab have provided early evidence to suggest that chickens may indeed be capable of emotional transfer, which is a fundamental component of an empathic response (Edgar, Nicol, Clark, & Paul, 2012). Nicol sets out the evidence for and against chickens' capacity for affiliation and empathy with clarity and objectivity. In Chapter 7, attention turns to individual level learning, intelligence and cognition, showing that in both learned and unlearned behaviour, chickens can be complex and flexible in their responses. Behavioural flexibility is the key to determining whether observed behaviour is ‘intelligent’ or evolved, and Nicol looks at how chickens' behavioural flexibility and repertoire permit their varied range of social and navigational capabilities. In the final chapters, Nicol explores some of the particular issues that arise in the two production types of broilers and broiler breeders (Chapter 8) and laying hens (Chapter 9). More specifically, these chapters
2
Book Review / Animal Behaviour 117 (2016) 1e2
discuss the broad range of research investigating the application of behavioural measures to animal welfare in these production systems. For broilers, the key issues considered are space use, activity, fearfulness and hunger, with the additional consideration of aggression and stress in broiler breeders. For laying hens, Nicol considers the behavioural (and welfare) consequences of different cage and noncage systems. This book is a beautifully clear insight into what a chicken is, how it perceives and processes the world around it, and how the systems we use to farm these birds in vast numbers impact them. It rather leaves one wondering what consequences may emerge from further intensification in future farming systems as human populations swell and dietary preferences worldwide trend further towards more meat consumption. Lisa M. Collins School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln LN7 6DL, U.K. E-mail address: [email protected].
References Appleby, M., Mench, J., & Hughes, B. O. (2004). Poultry behaviour and welfare. Wallingford, U.K.: CABI. Delgado, C., Rosegrant, M., Steinfeld, H., Ehui, S., & Courbois, C. (1999). Livestock to 2020: The next food revolution. Washington D.C.: International Food Policy Research Institute. Edgar, J. L., Nicol, C., Clark, C. C. A., & Paul, E. S. (2012). Measuring empathic responses in animals. Applied Animal Behavior Science, 138, 182e193. Fan, Y., Duncan, N. W., de Greck, M., & Northoff, G. (2011). Is there a core neural network in empathy? Neuroscience. Biobehavioral Reviews, 35, 903e911. FAOStat. 2016. http://faostat3.fao.org/home/E. Grandin, T., & Deesing, M. (2013). Genetics and the behaviour of the domestic animal. San Diego, CA: Academic Press. Harrison, R. (1964). Animal machines the new factory farming industry. New York, NY: Ballantine books. Kearney, J. (2010). Food consumption trends and drivers. Philosophical Transactions of the Royal Society B., 365, 2793e2807. Nicol, C. J. (2011). Behaviour as an indicator of animal welfare. In A. J. F. Webster (Ed.), The UFAW Farm Handbook: Management and welfare of farm animals (5th ed., pp. 31e67). Chichester, U.K.: Wiley-Blackwell. Shamay-Tsoory, S. G., Ahron-Peretz, J., & Perry, D. (2009). Two systems for empathy: a double dissociation between emotional and cognitive empathy in inferior frontal gyrus versus ventromedial prefrontal lesions. Brain, 12, 617e627.
Contents lists available at ScienceDirect
Animal Behaviour journal homepage: www.elsevier.com/locate/anbehav
Book Review The behavioural biology of chickens, Christine J. Nicol. Wallingford, U.K.: CABI (2015). Pp. 192. Price £75.00 hardback. The enormity in scale of numbers of chickens worldwide is astronomical. As the most popular global choice for meat, the number of meat chickens reared and killed in 2013 exceeded the number of humans alive on the planet by a scale of almost 10 to 1 (FAOStat, 2016). There are a lot of them, so it certainly makes sense to try to understand them. Several books written in the last few decades have included chicken behaviour and welfare to some extent (Appleby, Mench, & Hughes, 2004; Grandin & Deesing, 2013); however, most have focused principally on production systems and the welfare issues arising from these. While Nicol's book does include several chapters on production and welfare, the primary focus, and the key mark of difference for this book, is in its detail on the chicken's biology. In this book, Nicol, a world authority on chicken behaviour and welfare, explores the biology of this most popular of birds in such a clear, straight, and thoroughly engaging way that reading it is light work. This is most peculiar when one also considers the sheer volume of information that bursts out of every page. On reading it, one cannot help but marvel at just how underestimated the humble chicken is. Nicol opens her tour-de-force with a discussion of genetics and domestication in Chapter 1, where we are introduced to the changing ideas on chicken ancestry and domestication, the practices used in commercial breeding and the impacts of selective breeding programmes on the chicken's genome and behaviour. Chapter 2 on sensory biology makes light but thorough work of the dense literature on chicken vision, hearing, taste, olfaction and magnetoreception, leaving the reader with a clear sense of chicken perceptual abilities and limits, and the implications of these for their health and welfare. Chapter 3 continues apace, this time moving into the development of the avian brain, where we are led to understand how the evolving view of bird brains has brought us to a point where there is no solid argument against the possibility of chickens being capable of primary conscious experience. We have come a long way from the school of thought where birds were just another rung on the ladder to a massive, differentiated telencephalon. Nicol continues on to discuss epigenetic influences on embryonic development and brain lateralization ultimately leading to differences in behaviour in the birds as adults. This is fascinating, touching on the contrasting evidence supporting the alternative hypotheses that the mother has passive or active control of the environmental factors that may subsequently lead to alterations in the expression of genetic material in later life, and what the long-term consequences of this may be in terms of alterations in behaviour. The measurement of behaviour is one of the three key pillars of welfare assessment. The subject of animal welfare in relation to chickens in both of their commercial forms, the meatproducing broiler and the egg-laying hen, is one that has received http://dx.doi.org/10.1016/j.anbehav.2016.04.018 0003-3472
a great deal of both academic and public attention. The publication of Animal Machines (Harrison, 1964) raised the issue of welfare compromise as a consequence of agricultural intensification following World War II. Since the publication of Harrison's book, the number of chickens produced annually has increased more than five-fold (FAOStat, 2016). With year-on-year increases in demand for animal products, intensification is set to continue to escalate into the future (Delgado, Rosegrant, Steinfeld, Ehui, & Courbois, 1999; Kearney, 2010). In Chapter 4, Nicol turns to the study of behaviour as a means of understanding the underlying welfare state of an animal, the level of internal motivation it has to attain a resource or perform certain behaviours, and ultimately to understand what the bird itself considers to be its key priorities. This leads naturally into Chapter 5, where Nicol follows the idea of ‘behaviours that matter’ (Nicol, 2011), and are considered to be of relatively higher priority to the birds, to understand what factors can influence the performance of such behaviours within commercial systems, highlighting the large differences in daily activity budget and diversity in behavioural repertoires between broilers and laying hens. All chickens, regardless of their production type, are social animals. The nature and dynamics of their sociality depends on their life stage, the quantity and distribution of resources in the environment, and the seasons. In Chapter 6, Nicol turns to the social behaviour of chickens, discussing recognition and preferences by individuals, the overall social structure of a group and the spatiotemporal dynamics of social behaviour that allows a group to synchronize their individual behaviour patterns. In social groups demonstrating high levels of spatial or temporal clustering in behaviour, one might naturally consider the affiliative bonds between individuals, and investigate the extent to which they are capable of empathy for conspecifics; such factors have been shown to be of particular importance in human groups (Fan, Duncan, de Greck, & Northoff, 2011; Shamay-Tsoory, Ahron-Peretz, & Perry, 2009). Recent studies from within Nicol's research lab have provided early evidence to suggest that chickens may indeed be capable of emotional transfer, which is a fundamental component of an empathic response (Edgar, Nicol, Clark, & Paul, 2012). Nicol sets out the evidence for and against chickens' capacity for affiliation and empathy with clarity and objectivity. In Chapter 7, attention turns to individual level learning, intelligence and cognition, showing that in both learned and unlearned behaviour, chickens can be complex and flexible in their responses. Behavioural flexibility is the key to determining whether observed behaviour is ‘intelligent’ or evolved, and Nicol looks at how chickens' behavioural flexibility and repertoire permit their varied range of social and navigational capabilities. In the final chapters, Nicol explores some of the particular issues that arise in the two production types of broilers and broiler breeders (Chapter 8) and laying hens (Chapter 9). More specifically, these chapters
2
Book Review / Animal Behaviour 117 (2016) 1e2
discuss the broad range of research investigating the application of behavioural measures to animal welfare in these production systems. For broilers, the key issues considered are space use, activity, fearfulness and hunger, with the additional consideration of aggression and stress in broiler breeders. For laying hens, Nicol considers the behavioural (and welfare) consequences of different cage and noncage systems. This book is a beautifully clear insight into what a chicken is, how it perceives and processes the world around it, and how the systems we use to farm these birds in vast numbers impact them. It rather leaves one wondering what consequences may emerge from further intensification in future farming systems as human populations swell and dietary preferences worldwide trend further towards more meat consumption. Lisa M. Collins School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln LN7 6DL, U.K. E-mail address: [email protected].
References Appleby, M., Mench, J., & Hughes, B. O. (2004). Poultry behaviour and welfare. Wallingford, U.K.: CABI. Delgado, C., Rosegrant, M., Steinfeld, H., Ehui, S., & Courbois, C. (1999). Livestock to 2020: The next food revolution. Washington D.C.: International Food Policy Research Institute. Edgar, J. L., Nicol, C., Clark, C. C. A., & Paul, E. S. (2012). Measuring empathic responses in animals. Applied Animal Behavior Science, 138, 182e193. Fan, Y., Duncan, N. W., de Greck, M., & Northoff, G. (2011). Is there a core neural network in empathy? Neuroscience. Biobehavioral Reviews, 35, 903e911. FAOStat. 2016. http://faostat3.fao.org/home/E. Grandin, T., & Deesing, M. (2013). Genetics and the behaviour of the domestic animal. San Diego, CA: Academic Press. Harrison, R. (1964). Animal machines the new factory farming industry. New York, NY: Ballantine books. Kearney, J. (2010). Food consumption trends and drivers. Philosophical Transactions of the Royal Society B., 365, 2793e2807. Nicol, C. J. (2011). Behaviour as an indicator of animal welfare. In A. J. F. Webster (Ed.), The UFAW Farm Handbook: Management and welfare of farm animals (5th ed., pp. 31e67). Chichester, U.K.: Wiley-Blackwell. Shamay-Tsoory, S. G., Ahron-Peretz, J., & Perry, D. (2009). Two systems for empathy: a double dissociation between emotional and cognitive empathy in inferior frontal gyrus versus ventromedial prefrontal lesions. Brain, 12, 617e627.