The information in this chapter was important for three main reasons, the first demonstrating the need for Chinese panda institutions to begin systematically archiving fundamental historical information on every giant panda. Some data were recorded informally in individual keeper log books, and it was astonishing how much unrecorded information was in people's heads. Thus, one priority should be to establish a computerised record-keeping system, especially for the major breeding centres, which goes beyond the traditional Giant Panda Studbook (Xie & Gipps, 2003) and documents reproductive and health histories, including subjective assessments of important behaviours or personality traits.
Second, our analysis proved that no single behaviour or even cohort of traits was an absolute predictor of breeding success; this should not have been surprising. Just prior to the formal CBSG Biomedical Survey, Lindburg et al. (1997) examined a variety of factors potentially influencing reproductive success of male pandas housed in Chinese breeding centres and zoos. Lindburg and others (e.g. Zhang et al., 2004) determined that captive giant pandas often display inappropriate aggression when placed in mating situations. The present survey supported the importance of aggression as a determining variable, while additionally revealing a high correlation of mating success when both genders were characterised as 'aggressive'. It is apparent that there is some (as yet undefined) range of aggression that 'works' for this species - if an animal exceeds or shows less than the appropriate level, it probably will not successfully reproduce. Zhang and colleagues (2004) have suggested that a combination of temperament, stress and inadequate husbandry practices together contribute to reproductive failure. That study tracked 103 mating introductions involving a total of six males and 12 females where intromission did not occur. Of these copulatory failures, 47% were due to inability to mount properly (most likely due to sexual inexperience often related to age), and 33% were caused by lack of male interest. Zhang and colleagues (2004) suggested that timid females are less likely to breed, a result that the present study also supports, with an 'opposite' personality characteristic of aggression being one of the strongest predictors of breeding success. Of the six males in Zhang's study, the two that were the most successful breeders were also wild born, a finding also supported by the present study.
This is interesting given our third significant finding, that breeding success was highly related to origin: wild-born animals were more productive than their captive-born counterparts. Lindburg and colleagues (1997) have also addressed this issue briefly by stating that 'early rearing deficiencies could be one of several factors contributing to mating dysfunction in male adults'. Snyder and colleagues (2003, 2004; see also Chapter 14) have made progress in examining the potential effects of early rearing on later reproductive behaviour, particularly in males. In brief, behavioural development differs between dam- and hand-reared panda cubs, with the ultimate impact on later reproductive success still to be determined. Therefore, we agree that this factor merits intensive and immediate investigation, including identifying characteristics of the captive environment that perturb normal breeding behaviours. In fact, our finding of better overall reproduction in pandas of wild origin no doubt was linked to this same issue. It makes sense that offspring properly socialised by a mother in nature would have a better capacity to mate (even in captivity) compared to captive-born counterparts that receive less maternal care due to hand-rearing and/or early weaning. Mother-reared young ostensibly have also had the opportunity to learn appropriate expression of aggression or, conversely, to deal with aggression from conspecifics. Together, these findings re-affirm the assertions by Snyder and colleagues (2003; 2004; see also Chapter 14) that a priority for the future is not just sheer number of cubs but rather an emphasis on the 'quality' of offspring with the opportunity for normal behavioural development.
Nevertheless, a key question remains: what constitutes the behavioural essence of a 'quality' (i.e. successful) breeder - an individual that can consistently, naturally and successfully copulate and, for females, one that can always successfully rear cubs? While elucidating traits compatible with being a Prime Breeder, the present study (as part of the CBSG Biomedical Survey) has also generated even more questions. For example:
• What can be done to ensure that pandas are not only physically healthy but also behaviourally equipped to reproduce successfully and rear offspring?
• What are the enabling conditions necessary to achieve this goal in terms of enclosure design and husbandry practices associated with neonatal and juvenile management?
• Will this mean rejecting traditional approaches of maintaining giant panda pairs in favour of multigenerational groups to enhance both reproduction and socialisation (see Chapter 14)?
• Since aggression seems to be an inherent trait in wild giant pandas (especially males), how can we develop safe methods for encouraging breeding in such individuals?
• If an eventual goal of ex situ management is to contribute to reintroduction, then what are the behavioural competencies necessary for such animals to reproduce and survive in nature?
• How are such animals best 'created' ex situ?
All of these questions are of high priority as we seek to master the art of propagating giant pandas that are behaviourally, genetically and physiologically robust, manifesting the natural behaviours and behavioural flexibility that serve them so well in the wild.
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