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.

Populations experiencing dramatic declines in numbers become susceptible to a variety of demographic influences not seen in larger populations, and result in susceptibility to an extinction vortex. Many 'wild' populations of elephants are now clearly in the 'small population' biology paradigm, in terms of conservation [25][26][27]. In addition, due to their extremely complex social system, large body size, and concomitant slow demographic turnover, plus potential for cultural isolation issues [28], understanding these influences is integral to managing for their survival. Consequently, all remnant populations of elephants become of vital importance to their continued existence, and can essentially be regarded as a metapopulation. Currently, only a minority of free-ranging elephants exist in large undisturbed protected areas [29]. Intensively managed populations in small reserves therefore become increasingly important for conservation, particularly since land tenure and type of land use impact conservation outcomes for elephants [30].
Intensively managed populations of elephants in small reserves closely resemble populations of elephants in zoo populations, some of which are kept in extensive enclosures, similar to small fenced reserves, and are important for future survival of the species. Valuable research conclusions can be based on non-wild populations, including both domestic and zoo animals [16,31], and in particular, factors that influence longevity, health and reproduction in zoo populations are likely to also play a role in wild populations, particularly those that are intensively managed. Furthermore, such information will be of particular value for future intensive conservation efforts, including translocations, reintroductions and possible rewilding (e.g. [32,33]). Thus, we call attention to the role of zoo elephant population research to in-situ conservation efforts, and stress the importance of understanding welfare, as a component of the scales of integral research into elephant conservation.
This collection of papers takes an epidemiological approach to exploring the connections between the daily lives of elephants in captivity and their welfare (introduced in [34]). By taking a multi-institutional approach, the collection is able to explore the overall trends in data without the usual small sample size issues that plague studies of animals in captivity [35]. As pointed out, the group of studies revealed that social and management factors were strongly implicated for multiple welfare indicators, while exhibit space was found to be less important [34]. The collection is timely, not only because of the broad public interest in captive animal care and management, as the authors themselves stress [34], but because amidst the global decline in elephants, these analyses have implications for conservation of a species in crisis, since welfare impacts demography, including longevity and reproductive success. Thus, effective research in captive facilities can fill key knowledge gaps, to which the series of papers contribute. By using a cross-institutional design, the authors are able to assess both institutionspecific factors as well as factors that apply regardless of local management. In so doing, they assess factors associated with welfare, including housing and social environments [36], environmental enrichment [37], and social demography [38]. In addition, the authors assess impacts on physiological [39,40], physical [41,42] and behavioural outcomes [43,44], tying together patterns at multiple scales and dimensions.
This collection represents a timely collation of research using a collaborative, multi-institutional approach. This set of papers also represents the largest collected set of publications on the welfare of zoo elephants to date. Such a collaborative and innovative approach exemplifies the effort and research required to ensure the persistence of biodiversity globally, and elephants in particular.

Author Contributions
Wrote the paper: EZC SJR.