Table 1. The collation of potential elephant welfare parameters developed to date and applicable to free-ranging elephants.

Type of behaviour	Description	References
Arousal behaviour	Indicator of nervousness, fear or anxiety (may or may not culminate into stress), but also positive arousal (social encounters and interactions, obtaining a desired goal etc): with typical behaviours in a gradient from low arousal (listening, ears spread, head held high, tail held up, walk around) to high arousal (running, cluster formation, aggression, vocalisation, often associated excessive temporal gland secretion, diarrhoea).	[37, 38]
Low arousal
High arousal
Temporal Gland Secretion	(TGS) is not necessarily an indication of a negative experience; shown in various arousal reactions. Immediate reaction to a cause. The dry streak on the cheek is visible for quite a while; if fresh and seen constantly one can assume the animal is in constant stress.	[37, 39]
	Social Stress: elephants at the top of the hierarchy (e.g. matriarchs) show increased TGS. This is not the same as the TGS in musth bulls.
Vocalisations	Express emotions–positive and negative. Types of vocalisations and behavioural correlates indicate the valence (positive/negative) and arousal level. Especially calves in distress will emit loud vocalisations such as bellowing and screaming.	[40, 41]
Decreased Responsiveness	When all copying strategies fail, the elephant may go into depression or a state of apathy.	[29, 42, 43]
Change of behaviour pattern	Stress becomes distress when it incurs a biological cost so large that the animal needs to divert biological resources (e.g. energy) away from normal biological functions. There might be increased vigilance behaviour, or alternatively less diverse behaviour patterns and decreased responsiveness (depression, apathy).	[6, 44–47]
	Elephants change their activity patterns and range behaviour to become more nocturnal and increase their flight behaviour in areas where poaching occurs.
	They travel faster and more directional outside of protected areas.
Abnormal behaviour	Abnormal behaviour differs in pattern, frequency, or context from that which is shown by most members of the species in conditions that allow a full range of behaviour.	[47]
Lack of range use	Elephants with higher levels of glucocorticoids (GCs) or its metabolites may utilise less of the available range than elephants with similar range size and lower GC levels. This supports the spatial refuge hypothesis, and the authors suggest that chronic stress is associated with restricted space use. Translocated elephants displayed this behaviour and related higher GC levels for up to 6 years following a translocation event.	[36]
Avoidance/preference behaviour	Stimuli, events or other elephants that are disliked or induce fear, anxiety or stress are typically avoided (e.g. human disturbance). Stimuli events and elephants that are preferred will be sought out.	[48]
Loss of variability and complexity	One measure of behavioural stress is loss of variability and complexity of exploratory behaviour, as more energy is spent on increased metabolic rate. Not immediately visible, but careful data on detailed behavioural elements can show it in the analysis.	[49]
Social competence/incompetence	Social competence is the capacity to react in a species-specific way to social interactions and the ability of individuals to regulate the expression of their social behaviour to optimise their social relationships. Social competence involves capabilities to perceive and process social information, and to behave most appropriately in a given social context. The social environment encountered early in life can affect the expression of various social behaviours later in life in situations such as competition, forming dominance hierarchies, care for the young, and mating success.	[50–53]
	When the ability to interact socially with the mother and other group members in infancy is prevented, normal functioning later in life is disturbed.
	Social deprivation, specifically early separation from mother, results in development of severe and uncontrolled aggressive behaviour, intense anxiety reactions, inability to develop social relationships, unnatural startle responses, and lack of recognition of social signals and can be expressed in stereotypic behaviour.
Genetically fixed behaviours not achievable	Every species has its specific genetically fixed general requirements, such as feeding, social, health, body care, locomotion, resting. These requirements elicit species-specific behaviour patterns to achieve the goal. Behavioural responses can be due to endogenous (e.g. diurnal rhythm, hormones) or exogenous factors (e.g. visual, tactile or acoustic stimuli by conspecifics). If the goal cannot be reached by any species-specific behaviour, the animal can respond with frustration, anger, or contrary, depression and apathy (e.g. hardly any response to social contacts, no initiative to explore, standing doing nothing.). One well-known means of response used by captive animals is to resort to abnormal behaviours such as stereotypies.	[42, 44, 54]
Life expectancy	Life expectancy appears to be shorter in captive elephants, where none reached age >50, whereas life expectancy in an African elephant population not targeted by poaching is up to 60 years. Whereas the causes of death in captivity are manifold, it is interesting to note that in the Addo population confinement may well have had an adverse effect on the longevity of the elephants.	[12, 55–57]
Reproductive success	A study on African elephants revealed that social bonds, group composition and poaching risk significantly influenced a female elephant’s stress physiology. The results suggest that a disrupted social group creates a chronic stress condition for elephants, and this affects the reproductive success, as well as growth and immunity.	[24, 58]