Professor of Ethology Newcastle University, United Kingdom
What is animal welfare and why is it relevant to behavioural ecology? Animal welfare science is concerned with objectively quantifying the welfare of non-human animals with the aim of using this knowledge to improve welfare. Different definitions of animal welfare exist, but a widely-accepted definition focusses on affective state, whereby good welfare is characterised by the absence of negative affect and the presence of positive affect. Negative affective states include, fear, anxiety, depression, pain, boredom, frustration, hunger and thirst, whereas positive states include contentment, joy and excitement. Operationally, negative affective states are the physiological, cognitive and behavioural changes associated with punishing experiences that animals seek to avoid, whereas positive affective states are associated with rewarding experiences that animals seek to obtain. In humans, who are able to report their subjective feelings, negative affect is unpleasant and positive affect is pleasant. It is the likelihood that non-human animals may also experience these feelings that drives much research in animal welfare.
From an ultimate perspective, affective states are part of the physiological and neural machinery that has evolved to maintain homeostasis and motivate adaptive behaviour. For example, hunger motivates foraging and anxiety about predation motivates vigilance. Thus, while it is adaptive for animals to experience some negative affect, sustained presence of negative affect (or the absence of positive affect) is likely to indicate that an animal is failing to meet its physiological or behavioural needs; if an animal is always hungry it may be at risk from starvation and if it is always frightened it may be at risk from predation. However, chronic negative affective states can have important consequences for ecology aside from indicating increased probability of death. For example, chronically elevated fear of predation has been shown to have many subtle effects on prey animals (the 'landscape of fear'). My own research is concerned with understanding the ecology of food insecurity (FI), which is defined as limited and unpredictable access to nutritionally adequate food, and is characterised by hunger and anxiety about availability of food. FI causes a suite of evolved behavioural and physiological changes that reduce the risk of energetic shortfall, but which may involve reduced investment in somatic maintenance and immunity, indicating trade-offs in how energy is spent within the body. Given that FI is increasing in many wild animals as a result of anthropogenic environmental change, understanding its impacts on ecology has never been more important.
