Welfare at Multiple Scales: Importance of Zoo Elephant Population Welfare in a World of Declining Wild Populations

In-situ elephant populations have been in decline for much of the last 200 years, driven by an inexorable combination of habitat loss and hunting for ivory, but with more recent and dramatic declines primarily driven by hunting [1]. Consequently, the distribution and sustainability of elephant populations are now better predicted by human factors than ecological ones [2], underscoring the importance of societal factors in the ongoing survival of elephants. Despite growing awareness of the conservation crisis, hunting pressure has not abated. Instead, there has been a recent surge in harvest rates [3,4], more than doubling of harvest since 2007 [5]. The rates are staggering, escalating from an estimated 40,000 African elephants killed in 2011 [4] and 41 tons of ivory seized, to possibly more than 10% of the remaining populations in 2013 (summarised in [6]). In April 2016, the Kenyan Wildlife Service burned the biggest stockpile of ivory since it began burning ivory in 1989, with 105 tonnes of ivory destroyed, representing 6000–7000 poached elephants [7,8]. Similar declines have been seen in forest [3,9] and Asian [10] elephants. The current harvest rate of elephants is unsustainable, creating a conservation crisis of global significance, with an immediate threat to their continued survival [11]. Novel genetic tracing techniques (e.g [6]) and strict anti-poaching law enforcement [5] are vital to conserve the remaining free-ranging elephant populations. The significance of the current overharvesting crisis extends beyond obvious direct impacts on the number of elephants, to their demography, through a variety of influences. As large bodied mammals, with complex social interactions, social structures, and extended weaning periods, the impact of disruptions to demography are long-lasting. For example, matriarchs are a repository of social information [12], such that their loss can have a disproportionate impact on social cohesion, herd demography and fitness, and these effects can last for decades [13]. Furthermore, physiological stress can be increased in areas where elephants are exposed to anthropogenic stress [14,15], with potential impacts on reproductive senescence and lifetime reproductive success [16]. Finally, overharvesting can influence ecological dynamics beyond the harvested species, affecting larger food webs and ecological processes in the landscape [4,17]—including the loss of a large-scale ecological engineer and important seed-disperser [18–21]. The disruption caused by poaching is likely to exacerbate issues of human-wildlife conflict involving elephants, affecting the lives and livelihoods of local human communities [22–24]. This can also lead to the vicious cycle of ‘retaliatory’ killing, compounding population impacts. Therefore, the conservation crisis extends beyond the animals killed by poaching, to broad ecosystem and community impacts.