Zoos are duty bound to maintain a high standard of welfare for all animals for which they are responsible. For elephants, this represents a greater challenge than for many other species; their sheer size, sophisticated social life, high level of intelligence and large behavioural repertoire, combined with their origins in tropical and subtropical climates mean that replicating the physical, social and environmental requirements needed for a high standard of welfare in captivity is a significant challenge. This is compounded by the difficulties in measuring welfare generally, and specifically for animals such as elephants within zoo environments. Evidence does exist relating to the longevity, reproductive success and the health status of captive elephants which suggests that their management is not at as high a standard as it is for many other species kept in zoos, and that elephant welfare is likely to be compromised as a result. It is suggested that for as long as elephants remain in captivity that their management should be based around the requirements of the animals themselves taking into account an understanding of their biology and behavioural ecology. Given the difficulties in measuring welfare, it is suggested that those responsible for elephant management should not rely on proof of suffering prior to making adjustments to their programmes, but in the first instance consider the likely physical and behavioural needs of the elephant. As a minimum, facilities should provide for those behaviours and contingencies which are biologically significant in terms of survival and reproduction in the wild, which take up a significant proportion of an elephant's time in the wild and are not necessarily triggered by external stimuli alone. It is suggested that a high standard of captive elephant welfare is theoretically attainable and that significant improvements in welfare are likely to be achieved by addressing inadequacies in the physical environment which predispose captive elephants to trauma and by providing for appropriate social and foraging opportunities.

Animal welfare (sometimes termed ''well-being'') is about feelings -states such as ''suffering'' or ''contentment'' that we can infer but cannot measure directly. Welfare indices have been developed from two main sources: studies of suffering humans, and of research animals deliberately subjected to challenges known to affect emotional state. We briefly review the resulting indices here, and discuss how well they are understood for elephants, since objective welfare assessment should play a central role in evidence-based elephant management. We cover behavioral and cognitive responses (approach/avoidance; intention, redirected and displacement activities; vigilance/startle; warning signals; cognitive biases, apathy and depression-like changes; stereotypic behavior); physiological responses (sympathetic responses; corticosteroid output -often assayed noninvasively via urine, feces or even hair; other aspects of HPA function, e.g. adrenal hypertrophy); and the potential negative effects of prolonged stress on reproduction (e.g. reduced gametogenesis; low libido; elevated still-birth rates; poor maternal care) and health (e.g. poor wound-healing; enhanced disease rates; shortened lifespans). The best validated, most used welfare indices for elephants are corticosteroid outputs and stereotypic behavior. Indices suggested as valid, partially validated, and/or validated but not yet applied within zoos include: measures of preference/avoidance; displacement movements; vocal/postural signals of affective (emotional) state; startle/vigilance; apathy; salivary and urinary epinephrine; female acyclity; infant mortality rates; skin/foot infections; cardio-vascular disease; and premature adult death. Potentially useful indices that have not yet attracted any validation work in elephants include: operant responding and place preference tests; intention and vacuum movements; fear/ stress pheromone release; cognitive biases; heart rate, pupil dilation and blood pressure; corticosteroid assay from hair, especially tail-hairs (to access endocrine events up to a year ago); adrenal hypertrophy; male infertility; prolactinemia; and immunological changes. Zoo Biol 29:237-255,

Despite the diversity of animal welfare definitions, most recognise the centrality of the feelings of animals which are currently impossible to measure directly. As a result, animal welfare assessment is heavily reliant upon the indirect measurement of factors that either affect what animals feel, or are effected by how they feel. Physiological and health orientated measures have emerged as popular metrics for assessing welfare because they are quantifiable, can effect and be affected by how animals feel and have merits regardless of their relationship to the feelings of animals. However, their popularity in animal welfare assessment has led to them having a disproportionate influence on animal management to the detriment of animal welfare in numerous instances. Here, the case is made that a tension exists between management that prioritizes aspects of care reflecting popular animal welfare metrics such as those relating to physical health, and management that emphasizes psychological wellbeing. By re-examining the relative merits of physical and psychological priorities in animal management, an alternate animal welfare paradigm emerges less tied to traditional welfare metrics. This paradigm theorizes about the possibility for an optimal animal welfare state to exist where managed animal populations provided essential psychological outlets but protected from key physical stressors routinely experienced in the wild, might experience higher levels of welfare than wild populations would routinely experience. The proposition that optimal animal welfare could theoretically be achieved in well managed and well designed captive environments challenges a widely held ethical perspective that captivity is inherently bad for animal welfare.

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Summary 1.The speed with which small birds can get airborne is critical to the effectiveness of their escape response when attacked by a predator. However, take-off ability is likely to be affected by physiological changes occurring as a result of egg formation. 2. To investigate whether reduced take-off velocity is a cost of reproduction, the physiological costs of egg production in the Zebra Finch ( Taeniopygia guttata ) were experimentally manipulated by varying both the number of eggs a female laid and the quality of her prelaying diet. The effect of changes in postlaying flight muscle condition and body mass upon alarmed flight take-off velocity (a measure of escapeability in birds) was subsequently measured. 3. Changes in muscle condition were found to correlate positively with changes in various measures of flight velocity: treatments that caused the greatest declines in muscle condition during egg-laying were associated with the greatest declines in flight performance over this period. In contrast, breeding attempts that caused the smallest declines in muscle condition were associated with improvements in flight performance (i.e. birds flew faster at the end of laying than at the start). 4. These effects were independent of changes in body mass, and occurred postlaying, suggesting that the cost of egg production lies primarily in the formation of the eggs, rather than in carrying them as other studies had suggested. The observed trade-off between muscle loss resulting from egg production and escape ability could have important implications for the evolution of optimal clutch size in birds.