Ethical advantages of using domestic bird species for magnetic orientation research

Abstract

Identifying the mechanism in birds which controls magnetic orientation behaviour is proving elusive and is currently attracting a plethora of research activity. Much of this research involves wild birds which are caught in nets, tested and released. Ethical concerns regarding these experiments are likely to encompass the welfare of animals, their “rights” and conservation issues. Recently, Pekin ducks derived from migratory ancestors have been shown to posses a magnetic compass in a simple conditioning procedure. The use of domestic bird species provides a refinement in the ethics of animal experimentation since these birds are not caught in nets, are less fearful of humans and their use does not raise conservation concerns. The study of magnetic orientation is a high profile and fascinating areas of animal behaviour research and one in which behavioural scientists should be seen to actively embrace the principles of the 3R’s.

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The ability of migratory birds to use magnetic compass information to orient was first shown nearly forty years ago.1 Theoretical, behavioral and physiological evidence suggests that birds may have two magnetoreception mechanisms. Briefly, the magnetite-based mechanism assumes that magnetoreception is derived from particles of magnetite, a form of iron oxide which can align to magnetic fields, in the cells of animals.2 A second chemical magnetoreception mechanism assumes that magnetoreception is derived from chemical reactions that are modulated by Earth-strength magnetic fields.3 Identifying the precise functioning of these two mechanisms and their role in orientation behavior is, however, proving elusive and is currently attracting considerable research interest.

Behavioural tests of magnetic orientation in birds have invariably required testing of a strong directional response, which is usually migration direction.4 During the migration season, wild birds have a strong tendency to fly in a certain direction. By trapping birds during the migration season and placing them in an orientation cage, directional responses can be studied and, critically, shifted by applying a shifted artificial magnetic field. Birds for these experiments are typically caught in nets and tested in orientation cages, kept in cages at other times, and released once the tests are completed. These practices may cause distress to the target birds (and other birds unintentionally captured) and loss of fitness with possible effects on subsequent survival chances.5,6 Ethical concerns for these experiments are likely to encompass the welfare of animals, their “rights” to not be used for experimentation along with conservation issues.7 Several attempts have been made to use a directional response other than migration, but many of these attempts were initially unsuccessful because it was difficult to condition birds to magnetic directions.8

Recently though, the strong motivation of precocial birds to regain contact with a hidden imprinting stimulus (a ball) has allowed conditioning to magnetic directions.9,10 We trained Pekin ducks (Anas platyrhynchos domestica) to find a hidden imprinting stimulus behind one of three screens in a uniform circular arena. In unrewarded tests in the Geomagnetic field (Geomagnetic tests, Fig. 1), ducks showed a preference to search behind the screen in the direction that the imprinting stimulus had previously been hidden. In critical unrewarded tests the magnetic field was shifted clockwise by 120° by external coils running a current. In these latter Shifted-north tests, ducks shifted their search behavior also by 120° indicating the presence of a magnetic compass in this species10 (Fig. 1). The use of the domestic Pekin duck which is derived from the widely dispersed and migratory mallard duck (Anas platyrhynchos)11 represents a significant refinement in research ethics over wild-caught subjects. First, the use of a commercially available species means that animals do not have to be bred specifically for research—some estimates put the number of animals used in research at 115 million worldwide12—and can be returned to production systems after experimentation. Second, the birds are not wild-caught and so any adverse effects that trapping may cause and any conservation concerns raised by the use of wild species are avoided. Third, Pekin ducks have undergone domestication and this process leads to several behavioral changes such as reduced fearfulness,13 which is likely to be beneficial to bird welfare in response to handling and also reduce the risk of birds injuring themselves while in captivity.

The guiding principles of Russell and Burch's 3Rs14 which are widely accepted in consideration of the ethics of animal research at many levels should be at the forefront of every ethical scientist's mind. It has been argued that not only should animal behavior researchers consider the ethical implications of their research carefully, but that they should actively engage in this debate.15 To do so effectively, I would add, we must be seen to take every effort to consider the ethical implications of our research at all levels and where appropriate, consider “refinement, reduction or replacement” of our procedures on animals. If established researchers can consider the benefits of using domestic bird species after 40 years of magnetic orientation research,1,16 then perhaps this serves as an incentive for others in the field to continue to critically evaluate the ethical implications of their established research methodologies. The study of magnetic orientation is one of the most high profile and fascinating areas of animal behavior research and as researchers we are perhaps ideally placed to ensure that animal behavior research is seen as exemplary ethical research by the wider scientific community.

Figures and Tables

Figure 1 The back-transformed percentage of choices for each screen in the Geomagnetic and the Shifted-north field tests. Percentage choices for the screen in the training direction (TD), shifted direction (120° clockwise from the training direction) or the screen in the other direction are shown. Red lines and arrows indicate samples with a significant preference (p < 0.05) for a particular direction, black lines and rounded endings indicate significantly fewer choices than expected by chance. Black lines with a straight ending indicate choices that do not differ from chance level.10

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