Among mammals, the giant panda is reproductively unique. The female is a seasonal, monoestrual breeder, experiencing a single- two to three-day period of sexual receptivity once per year, presumably triggered by increasing day length. In the wild, male giant pandas compete with conspecifics for access to oestrous females (Schaller et al., 1985). Giant pandas produce copious sperm numbers (see Chapter 7), presumably as 'insurance' to ensure conception and the perpetuation of the male's genes if given the opportunity to mate during a female's brief window of fertility. Although the extraordinarily short oestrus is a fascinating biological trait, it does not appear to limit reproductive success in captivity given that a sexually compatible male is available and breeding occurs. It does, however, present challenges for captive management for cub production.

The wild-born giant panda cub stays with its mother for 1.5 to 2.5 years (Schaller et al, 1985). This almost always is not the case in Chinese zoos and breeding centres, because of the practice of promoting annual cub production by early weaning, usually before six months of age (see Chapter 14). The consequences of this short-term gain on long-term development remain a question, and studies are continuing on the

Giant Pandas: Biology, Veterinary Medicine and Management, ed. David E. Wildt, Anju Zhang, Hemin Zhang, Donald L. Janssen and Susie Ellis. Published by Cambridge University Press. # Cambridge University Press 2006.

impact of disrupted early rearing on adverse behaviours, including inappropriate aggression, inadequate sexual behaviour and/or incompetent maternal behaviour (see Chapter 14). These anomalies are rather common in the ex situ giant panda world. Many males tend to show aggressive rather than affiliative behaviours, even to females demonstrating strong oestrus. Some females also display 'weak' periods of sexual receptivity (low intensity interest in males and/or absent or feeble lordotic behaviour).

The manifestation of behavioural characteristics or 'personality' traits can be influenced by many different and possibly interacting factors, from rearing history to housing conditions. Genetic predispositions and interactions with the environment offer yet another layer of complexity, the 'nature versus nurture' paradigm (Lorenz, 1965; Wilson, 1975; Lewontin et al., 1984).

The Giant Panda Biomedical Survey afforded an important opportunity to determine if and how rearing history and behavioural (i.e. personality) characteristics influence an individual's ability to successfully reproduce. As each animal was evaluated, we collected extensive historical data from curators and senior keepers, and administered surveys to those people who knew the pandas best - the animal keepers. This chapter reviews trends and behavioural patterns in the giant panda that may (or may not) play a role in reproductive success.

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