What Is Wild Animal Welfare Physiology?
Most research on the welfare of animals is done in human-controlled settings like farms and zoos. However, most of the animals on Earth live in the wild. Studying animals in natural settings that are not directly managed by humans may help us understand — and protect — many species. This paper posits that the emerging field of wild animal welfare physiology can use physiological markers — that is, objective signs of how the body is functioning, such as heart rate — to measure the welfare of animals in their natural habitats.
The paper covers four topics related to wild animal welfare physiology: (1) the physiology of welfare in mammals and non-mammalian animals, (2) the field of wild animal welfare physiology compared to current research fields, (3) advantages and challenges of using physiological markers to measure welfare, and (4) the validation of physiological markers to measure welfare.
Physiology Of Welfare
The paper includes a glossary of terms related to physiology and welfare. Notably, the author uses the term “animal welfare” to refer to animals’ “affective states.” “Affective states” includes short-lived emotions and long-lasting moods.
In mammals, affective states (i.e., emotions) that start in the brain lead to a cascade of physical changes throughout the body. For example, experiencing fear triggers a fight/flight response that includes faster heart and breathing rates. On the other hand, experiencing calmness results in a rest/digest response that includes slower heart and breathing rates. What’s more, the cascade of changes works in the other direction, too — heart rates (i.e., physiological states) influence emotions (i.e., affective states in the brain). Still, it may be possible to use various physiological markers to measure (or “indicate”) welfare. These physiological markers include the presence of neurotransmitters, hormones, and inflammatory measures.
To complicate this further, there has been less research on the emotion-physiology connection in non-mammalian animals such as birds, reptiles, amphibians, fishes, and insects. The author emphasizes that there’s tremendous variation between species. In other words, there’s no universal pattern or standard for physiological markers of welfare.
Wild Animal Welfare Physiology Versus Existing Fields
The author conducted a literature search to compare the proposed field of wild animal welfare physiology to three existing fields: ecophysiology, conservation physiology, and animal welfare. The literature review included studies published between 2013-2022.
In ecophysiology and conservation physiology, only about 1-3% of studies had a welfare-related word in their title or abstract; in animal welfare, only 1.4% of studies included physiological measures of animals in natural habitats. The new field of wild animal welfare physiology would fill these research gaps by focusing on welfare, physiological markers, and wild animals.
Advantages And Challenges Of Using Physiological Markers
According to the author, physiological measures of welfare have multiple advantages over behavioral measures of welfare, including:
- increased objectivity (i.e., avoiding subjective observer biases),
- better basis for comparative studies (i.e., using the same physiological markers across several animal species), and
- improved precision of measuring welfare at a specific time.
Plus, physiological measures may be less time-consuming and more straightforward to collect, making it easier to study many individual animals at once (i.e., have larger sample sizes).
On the other hand, physiological measures of welfare come with many challenges. First, animal welfare scientists may not have expertise in physiological methods. Second, collecting physiological data (e.g., blood) may be invasive and disturb — or even kil l— wild animals. Less invasive approaches (e.g., analyzing feces) have potential, but it can be hard to figure out which sample came from which individual animal in the field. Third, it may be difficult to untangle the relationship between physiological markers and affective states because processes in the body constantly interact.
To address these challenges, the author recommends collaborating with physiologists, finding user-friendly portable devices, and — as described in the next section — confirming whether a physiological marker is an accurate measure of welfare.
Validating Physiological Markers To Measure Welfare
Validation is a scientific process of confirming whether a measure (e.g., plasma cortisol level) truly reflects what it’s supposed to measure (e.g., suffering). The author provides guidance for the validation process, including practical considerations of workload and cost. In addition, the author encourages approaches that combine multiple measures of welfare. For example, scientists could collect physiological and behavioral markers. Or, they could conduct “complementary captivity studies” that involve studying animals in the wild and in captivity to create a “network analysis” or large database.
In summary, this paper presents scientific, theoretical, and practical information for establishing a new field of wild animal welfare physiology. This paper is a useful resource for animal advocates interested in learning about physiology and scientific methods, and for those interested in further study in this direction. As the field develops, animal advocates can play an important role in promoting non-invasive, non-harmful research techniques that put the welfare of animals first.
https://doi.org/10.1111/brv.13009