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Introduction: Applied Ethology and Poultry Science
Symposium: Quantifying the Behavior of Poultry Introduction: Applied Ethology and Poultry Science JOY A. MENCH Department of Poultry Science, University of Maryland, College Park, Maryland 20742 (Received for publication August 13, 1991)
1992 Poultry Science 71:631-633
The study of the behavior of animals has been of interest to humans since ancient times. In History of Animals, Aristotle recorded his observations and speculations concerning what he called the "psychical qualities and attitudes" of diverse species of domesticated and wild animals, including poultry (Aristotle 1952:157-158): Hens, for instance, when they have beaten the cock in a fight, will crow like the cock and endeavor to tread him... on the death of a hen a cock has been seen to undertake the maternal duties, leading the chickens about and providing them with food, and so intent upon these duties as to cease crowing and indulging his sexual propensities.
Indeed, the domestication of agricultural and companion animals was dependent upon an understanding of animal behavior that enabled humans to exploit that behavior to their own advantage (Hale, 1969). As a formal scientific discipline, however, the study of the biological basis of behavior, known as ethology, is comparatively new. The Bavarian zoologist Konrad Lorenz, whose initial studies in the 1930s
involved observations of imprinting in geese, is generally considered to be the founder of the discipline of ethology. Lorenz shared the Nobel Prize in 1973 with two other pioneering ethologists, Nikko Tinbergen and Karl von Frisch. Traditional ethological studies emphasized the observation of animals in their natural environment. Such studies were thus largely descriptive rather than experimental, and involved the establishment of "ethograms", or catalogues of behaviors, for different species. Perhaps the most widely known of such naturalistic studies are those conducted by Goodall (1971) on the chimpanzees of the Gombe reserve, which provided the first evidence of the use of tools by animals. Behaviors in animals range from being comparatively fixed (instinctive) to being comparatively labile (learned), although most behaviors in higher vertebrates have both instinctive and learned components. Of particular interest to ethologists has been the determination of "how" and "why" behaviors are expressed, or proximate and ultimate causation. Proximate causation refers to the developmental, physiological, and neurobiological mecha-
631
Downloaded from http://ps.oxfordjournals.org/ at University of Georgia on May 30, 2015
ABSTRACT As a scientific discipline, the study of the biological basis of behavior in animals, ethology, is comparatively new. Ethologists have traditionally conducted primarily observational studies designed to ascertain the evolutionary significance of behaviors in wild animals. There is, however, a growing branch of ethology that is concerned with the application of ethological principles to areas such as the management and welfare of economically important species like poultry. Because of the complexity of the causation and expression of behaviors in animals, it is particularly important that such studies be rigorously designed and analyzed. The purpose of this symposium was to stimulate interest in the study of poultry behavior and welfare, and to provide information about current methodology in ethology. {Key words: behavior, applied ethology, poultry, welfare, confinement system)
632
MENCH
by natural selection, there has been growing concern about how intensive confinement systems impact behavior and thus animal welfare. The influential Committee to Enquire into the Welfare of Animals Kept Under Intensive Management Systems (Brambell, 1964), which was established by the British government in response to public pressure, concluded that farm animals had behavioral "urges" that were not satisfied by modern confinement systems. The subsequent criticisms of animal agriculture have centered primarily on the behavioral restrictions imposed on animals. Laying hens housed in typical commercial battery cages, for example, are deprived of the ability to perform normal roosting, nesting, grooming, and dustbathing behavior. Determining whether the hen suffers when a normal behavior is prevented, however, requires an understanding of the causation and function of the behavior as well as the strength of her motivation to perform the behavior. There is already a significant body of literature on social behavior, learning, and reproductive behavior in poultry (WoodGush, 1991). More information about these and other aspects of poultry behavior is essential both for addressing questions about animal welfare and for applying behavioral principles to the improvement of productivity. However, behavior is a complex phenomenon. It occurs not only at the level of the individual but at the level of the group, and it is elicited by a wide variety of neurobiological and hormonal mechanisms. In addition, the scientific evaluation of animal welfare requires not only the measurement of behaviors and their physiological correlates, but the assessment of such phenomena as the feelings, needs, and desires of animals. Because of this complexity, it is particularly important that behavioral studies be rigorously designed and analyzed in order to yield useful information. This symposium was designed to provide an overview of current methodology in behavioral research. The speakers chosen addressed techniques of observation and measurement of behavior, particularly social behavior, the analysis of causation from the viewpoint of motivation and welfare, and lastly, how behavioral knowledge could be applied to the improvement
Downloaded from http://ps.oxfordjournals.org/ at University of Georgia on May 30, 2015
nisms that influence behaviors, and ultimate causation refers to the evolutionary significance of behaviors. If the particular behaviors expressed are adaptive for an individual animal with respect to its survival and reproduction, the genes that control the development and expression of those behaviors will be transmitted to the next generation. In general, ethologists have been most interested in research that addresses questions about the ultimate causation of behavior. Recently within ethology there has been an increasing emphasis on interdisciplinary research, as well as the emergence of subdisciplines. These events have resulted in a broadening of the focus and a shift in emphasis of etiological studies. Of particular significance to animal scientists has been the development of the field of applied ethology, which is concerned with the application of ethological methodology and principles to such problems as pest and predator control, the management of economically important species, wildlife conservation, and animal welfare. Unlike traditional ethology, applied ethology tends to be experimentally based and concerned mainly with proximate causation, primarily because humans control reproduction and hence the inheritance of traits in domesticated and managed animals. However, it should be borne in mind that although artificial selection does indeed modulate behavior it rarely alters it fundamentally. Animals thus often still behave as if ultimate causation matters; that is, they behave in ways that have been strongly influenced by natural selection and that would lead to enhanced reproductive fitness in the wild. For example, the repertoire of behaviors in most modern poultry strains is virtually identical to that of their putative wild ancestor, the Burmese Junglefowl (Kruijt, 1964), although the frequencies and intensities of several behaviors have changed as an inadvertent consequence of selection for production traits. The only fundamental change that has occurred is the virtual elimination of incubation behavior in light-hybrid hens, a behavior that was disadvantageous for productivity and hence was directly selected against. Because the behavior of agricultural animals has been so strongly influenced
SYMPOSIUM: QUANTIFYING THE BEHAVIOR OF POULTRY
of management and animal well-being. It is hoped that these papers will stimulate further research in poultry behavior and welfare. REFERENCES
Goodall, J., 1971. In the Shadow of Man. Dell, New York, NY. Hale, E. B., 1969. Domestication and the evolution of behavior. Pages 22-44 in: The Behavior of Domestic Animals, 2nd ed. E.S.E. Hafez, ed. Williams and Wilkins, Baltimore, MD. Kruijt, J. P., 1964. Ontogeny of social behavior in Burmese Red Junglefowl (Gallus gallus spaedicius). Behaviour (Suppl. 12). Wood-Gush, D.G.M., 1991. The development of applied ethology in relation to certain agricultural animals over a century. Pages 17-24 in: Applied Animal Behaviour Past, Present and Future. M. C. Appleby, R. I. Horrell, J. C. Petherick and S. M. Rutter, ed. Universities Federation for Animal Welfare, Potters Bar, England.
Downloaded from http://ps.oxfordjournals.org/ at University of Georgia on May 30, 2015
Aristotle, 1952. History of Animals. Pages 156-157 in: The Works of Aristotle, Vol. 2. Encyclopaedia Britannica, Chicago, IL. BrambelL F. R., 1964. The Report of the Technical Committee to Enquire into the Welfare of Animals Kept Under Intensive Livestock Husbandry Systems. Her Majesty's Stationery Office Command Report No. 2836, London, England.
633
1992 Poultry Science 71:631-633
The study of the behavior of animals has been of interest to humans since ancient times. In History of Animals, Aristotle recorded his observations and speculations concerning what he called the "psychical qualities and attitudes" of diverse species of domesticated and wild animals, including poultry (Aristotle 1952:157-158): Hens, for instance, when they have beaten the cock in a fight, will crow like the cock and endeavor to tread him... on the death of a hen a cock has been seen to undertake the maternal duties, leading the chickens about and providing them with food, and so intent upon these duties as to cease crowing and indulging his sexual propensities.
Indeed, the domestication of agricultural and companion animals was dependent upon an understanding of animal behavior that enabled humans to exploit that behavior to their own advantage (Hale, 1969). As a formal scientific discipline, however, the study of the biological basis of behavior, known as ethology, is comparatively new. The Bavarian zoologist Konrad Lorenz, whose initial studies in the 1930s
involved observations of imprinting in geese, is generally considered to be the founder of the discipline of ethology. Lorenz shared the Nobel Prize in 1973 with two other pioneering ethologists, Nikko Tinbergen and Karl von Frisch. Traditional ethological studies emphasized the observation of animals in their natural environment. Such studies were thus largely descriptive rather than experimental, and involved the establishment of "ethograms", or catalogues of behaviors, for different species. Perhaps the most widely known of such naturalistic studies are those conducted by Goodall (1971) on the chimpanzees of the Gombe reserve, which provided the first evidence of the use of tools by animals. Behaviors in animals range from being comparatively fixed (instinctive) to being comparatively labile (learned), although most behaviors in higher vertebrates have both instinctive and learned components. Of particular interest to ethologists has been the determination of "how" and "why" behaviors are expressed, or proximate and ultimate causation. Proximate causation refers to the developmental, physiological, and neurobiological mecha-
631
Downloaded from http://ps.oxfordjournals.org/ at University of Georgia on May 30, 2015
ABSTRACT As a scientific discipline, the study of the biological basis of behavior in animals, ethology, is comparatively new. Ethologists have traditionally conducted primarily observational studies designed to ascertain the evolutionary significance of behaviors in wild animals. There is, however, a growing branch of ethology that is concerned with the application of ethological principles to areas such as the management and welfare of economically important species like poultry. Because of the complexity of the causation and expression of behaviors in animals, it is particularly important that such studies be rigorously designed and analyzed. The purpose of this symposium was to stimulate interest in the study of poultry behavior and welfare, and to provide information about current methodology in ethology. {Key words: behavior, applied ethology, poultry, welfare, confinement system)
632
MENCH
by natural selection, there has been growing concern about how intensive confinement systems impact behavior and thus animal welfare. The influential Committee to Enquire into the Welfare of Animals Kept Under Intensive Management Systems (Brambell, 1964), which was established by the British government in response to public pressure, concluded that farm animals had behavioral "urges" that were not satisfied by modern confinement systems. The subsequent criticisms of animal agriculture have centered primarily on the behavioral restrictions imposed on animals. Laying hens housed in typical commercial battery cages, for example, are deprived of the ability to perform normal roosting, nesting, grooming, and dustbathing behavior. Determining whether the hen suffers when a normal behavior is prevented, however, requires an understanding of the causation and function of the behavior as well as the strength of her motivation to perform the behavior. There is already a significant body of literature on social behavior, learning, and reproductive behavior in poultry (WoodGush, 1991). More information about these and other aspects of poultry behavior is essential both for addressing questions about animal welfare and for applying behavioral principles to the improvement of productivity. However, behavior is a complex phenomenon. It occurs not only at the level of the individual but at the level of the group, and it is elicited by a wide variety of neurobiological and hormonal mechanisms. In addition, the scientific evaluation of animal welfare requires not only the measurement of behaviors and their physiological correlates, but the assessment of such phenomena as the feelings, needs, and desires of animals. Because of this complexity, it is particularly important that behavioral studies be rigorously designed and analyzed in order to yield useful information. This symposium was designed to provide an overview of current methodology in behavioral research. The speakers chosen addressed techniques of observation and measurement of behavior, particularly social behavior, the analysis of causation from the viewpoint of motivation and welfare, and lastly, how behavioral knowledge could be applied to the improvement
Downloaded from http://ps.oxfordjournals.org/ at University of Georgia on May 30, 2015
nisms that influence behaviors, and ultimate causation refers to the evolutionary significance of behaviors. If the particular behaviors expressed are adaptive for an individual animal with respect to its survival and reproduction, the genes that control the development and expression of those behaviors will be transmitted to the next generation. In general, ethologists have been most interested in research that addresses questions about the ultimate causation of behavior. Recently within ethology there has been an increasing emphasis on interdisciplinary research, as well as the emergence of subdisciplines. These events have resulted in a broadening of the focus and a shift in emphasis of etiological studies. Of particular significance to animal scientists has been the development of the field of applied ethology, which is concerned with the application of ethological methodology and principles to such problems as pest and predator control, the management of economically important species, wildlife conservation, and animal welfare. Unlike traditional ethology, applied ethology tends to be experimentally based and concerned mainly with proximate causation, primarily because humans control reproduction and hence the inheritance of traits in domesticated and managed animals. However, it should be borne in mind that although artificial selection does indeed modulate behavior it rarely alters it fundamentally. Animals thus often still behave as if ultimate causation matters; that is, they behave in ways that have been strongly influenced by natural selection and that would lead to enhanced reproductive fitness in the wild. For example, the repertoire of behaviors in most modern poultry strains is virtually identical to that of their putative wild ancestor, the Burmese Junglefowl (Kruijt, 1964), although the frequencies and intensities of several behaviors have changed as an inadvertent consequence of selection for production traits. The only fundamental change that has occurred is the virtual elimination of incubation behavior in light-hybrid hens, a behavior that was disadvantageous for productivity and hence was directly selected against. Because the behavior of agricultural animals has been so strongly influenced
SYMPOSIUM: QUANTIFYING THE BEHAVIOR OF POULTRY
of management and animal well-being. It is hoped that these papers will stimulate further research in poultry behavior and welfare. REFERENCES
Goodall, J., 1971. In the Shadow of Man. Dell, New York, NY. Hale, E. B., 1969. Domestication and the evolution of behavior. Pages 22-44 in: The Behavior of Domestic Animals, 2nd ed. E.S.E. Hafez, ed. Williams and Wilkins, Baltimore, MD. Kruijt, J. P., 1964. Ontogeny of social behavior in Burmese Red Junglefowl (Gallus gallus spaedicius). Behaviour (Suppl. 12). Wood-Gush, D.G.M., 1991. The development of applied ethology in relation to certain agricultural animals over a century. Pages 17-24 in: Applied Animal Behaviour Past, Present and Future. M. C. Appleby, R. I. Horrell, J. C. Petherick and S. M. Rutter, ed. Universities Federation for Animal Welfare, Potters Bar, England.
Downloaded from http://ps.oxfordjournals.org/ at University of Georgia on May 30, 2015
Aristotle, 1952. History of Animals. Pages 156-157 in: The Works of Aristotle, Vol. 2. Encyclopaedia Britannica, Chicago, IL. BrambelL F. R., 1964. The Report of the Technical Committee to Enquire into the Welfare of Animals Kept Under Intensive Livestock Husbandry Systems. Her Majesty's Stationery Office Command Report No. 2836, London, England.
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