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Continuing challenges of elephant
captivity: the captive environment, health
issues, and welfare implications
Catherine Doyle
1
, Heather Rally
2
, Lester O’Brien
3
,
Mackenzie Tennison
4
, Lori Marino
5,6
and Bob Jacobs
7
1Performing Animal Welfare Society, San Andreas, California, United States
2Thrive Wild LLC, Ventura, California, United States
3Palladium Elephant Consulting Inc., Calgary, Alberta, Canada
4Department of Psychology, University of Washington, Seattle, Washington, United States
5Whale Sanctuary Project, Washington DC, United States
6Animal Studies, Department of Environmental Studies, New York University, New York, New
York, United States
7Neuroscience Program, Department of Psychology, Colorado College, Colorado Springs,
Colorado, United States
ABSTRACT
Although the well-being of elephants in captivity is of paramount importance, the
confinement of these long-lived, highly intelligent, and socially complex animals
continues to present significant challenges. Here, we provide an overview of the
current state of elephant confinement (primarily in the West) by examining captive
facilities, improvements, and continuing problems, and the clinical/behavioral/
neural issues that remain. Specifically, we examine quantitative and qualitative
aspects of the enclosed space, sociocognitive factors, dietary differences, and health/
welfare concerns (e.g., stereotypies, physical health, nutrition, reproduction, life
expectancy). The challenges of the captive environment become especially salient
when juxtaposed next to the complex, multifaceted characteristics of the elephant’s
natural environment. Despite the best efforts of some facilities to improve the captive
environment, serious welfare challenges remain. Such confinement issues thus raise
important welfare and ethical concerns with regards to captive elephant well-being.
Subjects Animal Behavior, Ethical Issues
Keywords Captivity, Welfare, Elephant, Ethics, Zoo
INTRODUCTION
Elephants, as “charismatic megafauna”, have long been considered “problematic”
candidates for captivity (Hosey, Melfi& Ward, 2020, p. 486), posing practical challenges
and ethical concerns (Clubb et al., 2008;Poole & Granli, 2009;Mason, 2010;Riddle &
Stremme, 2011;Doyle, 2018;Rees, 2021). Public attention continues to focus on their
confinement and whether elephants’needs can be met to an acceptable level in captive
situations, particularly zoos. Zoological professionals also are increasingly concerned about
the effects of management practices on elephant well-being (Greco et al., 2017). Although
many countries have laws that regulate the care of animals to better protect their welfare
(Rees, 2011), the laws generally are not specific to individual species such as elephants.
How to cite this article Doyle C, Rally H, O’Brien L, Tennison M, Marino L, Jacobs B. 2024. Continuing challenges of elephant captivity:
the captive environment, health issues, and welfare implications. PeerJ 12:e18161 DOI 10.7717/peerj.18161
Submitted 18 June 2024
Accepted 2 September 2024
Published 30 September 2024
Corresponding author
Catherine Doyle,
cdoyle@pawsweb.org
Academic editor
Alan McElligott
Additional Information and
Declarations can be found on
page 27
DOI 10.7717/peerj.18161
Copyright
2024 Doyle et al.
Distributed under
Creative Commons CC-BY 4.0
Most elephant range countries (apart from India; Central Zoo Authority (India), 2008)do
not have a national strategy addressing their captive elephant populations (Riddle &
Stremme, 2011). With one exception (e.g., see the UK Secretary of State’s Standards of
Modern Zoo Practice, which includes an appendix on the keeping of elephants in zoos—
Department for Environment & Food and Rural Affairs, 2012), government licensing
authorities do not generally have requirements for best practices specific to elephants.
Some zoo accrediting organizations have developed elephant-specific requirements in
order to standardize management and to establish a minimum level of care across zoos
(e.g., Association of Zoos and Aquariums, AZA; British and Irish Association of Zoos and
Aquariums, BIAZA; European Association of Zoos and Aquariums, EAZA; Zoo and
Aquarium Association-Australia, ZAA; Japan Association of Zoos and Aquariums-JAZA).
Although such standards represent potential progress for the care of captive elephants,
these facilities remain largely constrained by what is practicable in the zoo setting (Clubb &
Mason, 2002), particularly in terms of space and social group size. Even under the highest
standards, there remain unique if not formidable problems in meeting animals’essential
needs in zoos (e.g., space, social groupings, foraging opportunities, autonomy, choice, and
cognitive challenges; Morgan & Tromborg, 2007;Shepherdson & Carlstead, 2020).
The scope of the problem for captive elephants is broad insofar as ~17,000 elephants are
held in various types of captivity around the world (Riddle & Stremme, 2011;Jackson et al.,
2019). About 14,000 of those are Asian elephants living outside of traditional zoos across
13 range countries, mostly in temples, logging camps, and tourism facilities (Ghimire et al.,
2024). Globally, ~1,627 elephants are held in zoos. Zoos in Asia hold the highest number of
elephants (~723), followed by Europe (~499), North America (~286), Latin America (~70),
Australia (~26), and Africa (~25) (The Elephant Database, 2024). Of the ~10,000–12,000
zoos and animal parks in the world, fewer than 2.3% appear to be accredited (Bacon, 2018).
Moreover, up to 95% of all zoos may not be meeting good practice standards for animal
welfare (Bacon, 2018). Indeed, elephants are held in a variety of captive environments,
typified by but not limited to zoos, as elephants are also kept in circuses, sanctuaries, and
work/tourist camps. In the U.S., for example, there are ~365 elephants, with ~262 kept in
zoos, ~47 in circuses or other commercial enterprises (e.g., rides, encounters, private
events), 21 in sanctuaries, and at least 35 in other facilities (e.g., conservation centers) (The
Elephant Database, 2024). Across captive facilities, there are significant differences in
terms of space (both quantity and quality), substrate, amount of exercise, nutritional/
husbandry needs, social/housing conditions, and level of human interactions (Greco et al.,
2016b;Shepherdson & Carlstead, 2020). Although Western zoos have strived to address
these conditions, including improving enclosures with more naturally appearing landscape
immersion designs, environmental enrichment, and, in some zoos, more space and social
opportunities, they are still wanting in many fundamental respects, especially for larger
animals, of which elephants are the quintessential example (Hancocks, 2002).
Although the science of captive animal welfare is growing steadily, with increased
attention paid to large mammals such as elephants (Whitham & Wielebnowski, 2013;
Shepherdson & Carlstead, 2020), research indicates that some animals, including elephants,
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 2/41
do not fare well in captivity (Clubb & Mason, 2003;Morgan & Tromborg, 2007;
Mason, 2010;Fischer & Romero, 2018). Although the terms “welfare”and “well-being”are
sometimes used interchangeably, some authors make a distinction between the two
(Fraser, 1992;Martelli & Krishnasamy, 2023). Animal well-being refers to the internal state
of the individual whereas animal welfare encompasses management systems used to
promote well-being (Martelli & Krishnasamy, 2023). In the present review, we are
concerned not only with the effects of captive management systems (i.e., welfare) but also
the day-to-day physical, mental, and emotional health (i.e., well-being) of the animals.
There are both negative (e.g., stereotypy, defined as invariant, repetitive movements with
no apparent function; Mason, 1991;Jacobs et al., 2021) and positive welfare measures. As
noted by Miller et al. (2020), absence of negative welfare markers does not, in and of itself,
indicate good welfare. For this reason, they suggest five positively-framed welfare markers,
or “opportunities to thrive”: (1) opportunity for a thoughtfully presented, well-balanced
diet, (2) opportunity for self-maintenance (including shelter and species-specific
substrates), (3) opportunity for optimal health (including a supportive environment that
increases the likelihood of good health), (4) opportunity to express species-specific
behavior (including quality spaces and appropriate social groupings), and (5) opportunity
for choice and control to avoid suffering and distress and to make behavior meaningful
(Vicino & Miller, 2015;Miller et al., 2020).
With these opportunities in mind, we reviewed the literature to examine the extent to
which the care of elephants meets these opportunities to thrive, with the aim of identifying
the challenges that remain in achieving them. This includes an overview of the behavioral
and clinical factors for elephants in captivity. We focused on the most recent findings and
representative facilities which, in many cases, are accredited by professional organizations
(e.g., AZA) and, as such, are considered to provide a higher level of care than other
elephant-holding facilities (Bansiddhi et al., 2020). These accrediting organizations are
found in the Global North (e.g., Australia, Canada, Europe, Japan, United Kingdom, and
United States) and their members hold ~56% of the elephants in zoos. However, we
recognize that elephants are found in a variety of settings worldwide that present potential
health and welfare problems, such as circuses and traveling shows, roadside attractions,
rides, tourism, and controlled “encounters”during which people feed, touch or bathe
elephants (Kontogeorgopoulos, 2009;Grotto et al., 2020;Iossa, Soulsbury & Harris, 2009).
Although our focus is on accredited facilities, many of the issues we explore here (e.g.,
stereotypy) are common to captive elephants around the world (Vanitha, Thiyagesan &
Baskaran, 2016;Bansiddhi, Brown & Thitaram, 2020;Bansiddhi et al., 2020;Fuktong et al.,
2021). Finally, we will suggest potential next steps for the well-being of elephants in
captivity.
LITERATURE REVIEW METHODOLOGY
We conducted a scoping review of the literature (Munn et al., 2018) on captive elephant
welfare and on free-roaming Asian (Elephas maximus) and African (Loxodonta africana)
elephants. Topics relevant to captive elephant welfare, both positive and negative, had been
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 3/41
previously identified in the existing literature: locomotion/walking rates/distances, body
condition/health, stereotypies, sociality, play, foraging, rest, reproduction, housing,
management (e.g., enrichment, feeding, exercise), space and complexity, behavioral
diversity, keeper-elephant relationships (Asher, Williams & Yon, 2015;Meehan et al.,
2016b;Chadwick et al., 2017;Williams et al., 2018;Meehan et al., 2019;Yon et al., 2019;
Miller et al., 2020;Ghimire et al., 2024). After a review of that literature, and with these
factors in mind, we organized the article into physical and behavioral elements important
to elephant welfare (e.g., space and complexity, walking, sensory, physical environment,
sociality, health issues, feeding, cognitive demands, human interactions), which became
the basis for our searches. Subsequent searches were based on keywords that are
characteristic of captive settings and important to the health and well-being of captive
elephants: lifespan, mortality, welfare, sociality, enrichment, health, well-being, cognition,
diet, nutrition, housing, zoos, exercise, digestion, reproduction, disease (e.g., osteoarthritis,
infectious diseases, obesity, foot disorders, dental issues), stereotypy, brain, sanctuaries,
captivity, keeper-elephant relationships. We also incorporated information on
free-roaming elephants such as habitats, ecology, sociality, foraging, diet, cognition, and
behavior. Our primary searches were done through Google Scholar and PubMed. Other
sources included our own publications and citation sections of published scientific papers.
We selected only fully accessible publications. Exclusions included non-permanent
facilities (e.g., circuses), effects of elephants on zoo visitors, veterinary techniques, and
commentaries. Considering new perspectives on welfare and the continuing challenges for
elephants in captive situations, we excluded articles published prior to 2,000 except for
those we considered foundational.
We used several sources of verifiable information in this review, with a total of 217
sources. The predominant source was peer-reviewed scientific literature (n= 165),
followed by chapters in edited books (n= 24), scientific books (n= 3), and one newspaper
article. Gray literature (e.g., conference proceedings, white papers, government
documents) was used sparingly (n= 14). Priority was given to the most recent findings so
that the information in the article represents the most current overview possible. All but
five citations were for publications after the year 2000, with 138 in the last 10 years
(2014–2024), and 65 in the 10–20 year-old range (2004–2013). Webpages of professional
organizations (e.g., AZA) were accessed for information about their standards and
guidelines. We focused on information about Western, mostly accredited, captive elephant
facilities but did not exclude other information. Overall, our goal was to conduct a
comprehensive search of factors relevant to the health and well-being of elephants in zoos,
including findings that best represented current welfare issues for these animals. Moreover,
we did not selectively exclude scientificfindings that supported conflicting views about
captive elephant welfare, as we wanted an accurate and complete picture of the status of
captive elephants. To ensure we were conducting a comprehensive search, we examined
the citation lists of all articles so that we did not omit any relevant article. Finally, when
findings appeared in secondary sources (e.g., review article, gray literature) we always
confirmed them in the primary source.
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 4/41
THE CAPTIVE ENVIRONMENT
The captive environment is multi-dimensional, encompassing several factors that affect
both physical and behavioral elements of elephant welfare: captive space and complexity,
movement, sensory experience and mental stimulation, diet and opportunities for
foraging, and social opportunities.
Enclosures
Although quantity of space is not explicitly mentioned in Vicino & Miller’s(2015)
opportunities to thrive, it would seem to be a necessary component insofar as large,
complex areas can sustain larger social groups of elephants, thus affording more
opportunities for positive welfare by allowing choice, autonomy, and increased behavioral
diversity. Alternatively, smaller elephant groups could also benefit from the positive
welfare provided by larger spaces. Significant public attention has been directed at the
housing and care of elephants (Meehan et al., 2016b), with that attention often focused on
space. The scientific literature addressing free-living elephants indicates that, based on
their large size and natural history, space is a key component of physical, behavioral, social,
and mental well-being (Poole & Granli, 2009). Meehan et al. (2016b) note that space is a
limited resource for zoos, and state that adequate space is required to support larger social
groupings as well as robust feeding and enrichment programs; however, an “adequate”
amount of space is not specified. An increase in space available to an elephant may also
benefit metabolic health, but only if the increase in space is “substantial”(Morfeld &
Brown, 2017, p. 11). Space limitations may be particularly problematic for male elephants,
who range more widely in the wild than do family groups (Hartley, Wood & Yon, 2019).
During musth, a period of heightened aggression and sexual drive (Ghosal et al., 2013),
free-ranging males increase their range sizes and intermingle with multiple family units as
they search for females in estrus (Fernando et al., 2008). Captive musth males also increase
their movement and overall activity even though they remain constrained by their
enclosures (LaDue et al., 2022a). Unlike free-ranging male elephants, captive males appear
to have an elevated stress response during musth, although LaDue et al. (2022a) urge
caution when interpreting wild-zoo differences due to sampling issues. Whereas providing
access to females for mating may improve welfare, this may not be an option in all
situations. It is worth noting that enclosure size is considered to be more important by
scientists than by zoo personnel (Gurusamy, Tribe & Phillips, 2023). Just as the size of a
species can affect its perception of enclosure complexity (de Azevedo et al., 2023), the size
assessments that captive elephants make of their enclosures may potentially suffer from a
floor effect insofar as all captive spaces may simply be too small from the perspective of
elephants, whose home ranges are several orders of magnitude larger than even the largest
zoo enclosure (Atkinson & Lindsay, 2022).
In zoos, researchers have found that factors other than space have an effect on elephant
welfare (Meehan et al., 2016b). In their epidemiological study of African and Asian
elephant welfare in 68 accredited North American zoos, Meehan et al. (2016b) determined
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 5/41
that measures of space were not identified as risk factors for certain welfare outcomes (e.g.,
stereotypies, obesity, female reproductive dysfunction). However, in accordance with a
possible floor effect, they acknowledged that their investigation was “limited to the range of
exhibit sizes at participating North American zoos [i.e., 118 to 15,765 m
2
], and future
studies incorporating larger areas could potentially find associations between space and
welfare outcomes”(p. 7). With relatively little variation in zoos, and with no zoos
approximating even the smallest range space available to elephants in the wild, measuring
the effect of zoo enclosure size on welfare is challenging (Mason & Veasey, 2009). In their
natural habitat, elephants have expansive home ranges, extending from tens to 10,000 km
2
(Fernando et al., 2008;Ngene et al., 2017;Bahar, Kasimi & Hambali, 2018). Enclosure sizes
for captive elephants vary. Some zoo accrediting agencies specify minimum space
standards for outdoor spaces ranging from 500 m
2
per elephant (AZA, 2021b)toa
minimum shared space of 3,000 m
2
(BIAZA, 2019). Minimum indoor stall size varies from
47 m
2
for one female elephant (AZA, 2021b) to 300 m
2
for four females (BIAZA, 2019),
even though an elephant can spend a significant amount of time indoors (Greco et al.,
2016a). Although some larger exhibits exist (e.g., Disney’s Animal Kingdom: 28,300 m
2
;
San Diego Zoo Safari Park: 13,000 m
2
), the actual size of most outdoor enclosures in a
sampling of 20 Western zoos (and three Eastern elephant centers) appears to be in the
range of 17–6,937 m
2
per animal (Taylor & Poole, 1998), which is orders of magnitude
smaller than their natural habitat—we note that more recent data on this issue are
necessary. More recently, Meehan et al. (2016a) evaluated not only total exhibit size, but
the individual elephant’s experience based on the time they spent in different subdivisions
of the exhibit. Calculated Total Space Experience (measurements of area as a function of
time) values ranged from 117 to 15,742 m
2
(mean Overall Total Space Experience for
African elephants was 3,642 and 1,781 m
2
for Asian elephants). For elephants in captive
environments, given that an elephant can typically cover every section of a 10,000 m
2
enclosure in less than an hour, Atkinson & Lindsay (2022) suggest that an enclosure should
be one or two orders of magnitude (i.e., ~1 km
2
) greater than traditional zoo exhibits. They
note that such an enclosure then would allow for (1) a sufficient quantity and diversity of
vegetation for normal foraging behaviors as well as visual screening, and (2) dozens of
widely distributed focal points (e.g., pools, rubbing rocks, sand mounds) for socialization
and possible avoidance behaviors. Moreover, they suggest that a more tropical climate,
similar to African and Asian elephants’natural habitat, would be preferable (as opposed to
an arctic climate as in northern Canada). Atkinson & Lindsay (2022) conclude that range
countries are the only places where elephants can truly flourish.
The issue of space in zoos is challenging, as zoos tend to be situated in urban
centers, limiting possibilities for significant expansion. Schmidt & Kappelhof (2019)
acknowledge that huge investments would be necessary to transform European
elephant exhibits into complex fission-fusion housing systems and to create more capacity
for male elephants. For zoos to maintain compatible herds, facilitate social behaviors, and
manage male elephants, it would require “substantial financial investment, large
physical spaces of many hectares [1 hectare ¼10,000 m
2
] and considerable expertise in
elephant management”(Hartley, Wood & Yon, 2019, p. 74). Some zoos in the U.S. have
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 6/41
been investing in exhibit renovations at great cost, for relatively small expansions. The Fort
Worth Zoo recently invested $32 million to improve their 12,141 m
2
elephant enclosure
(Fort Worth Zoo, 2024); the Cincinnati Zoo will spend $50 million for a 20,234 m
2
area
(Miller, 2023); and the Memphis Zoo recently announced a $250 million plan to renovate
their exhibits for African elephants, rhinoceroses, and giraffes (Moore, 2024). Future
research will be required to determine if these renovations have the effect of significantly
improving elephant well-being. For now, improvement in zoo association elephant
standards for space, social groupings, and male elephants may force zoos to invest in
exhibit changes. In addition, research conducted in non-zoo facilities that provide much
larger, more complex spaces (e.g., sanctuaries, conservation centers, semi-captive
situations) could potentially improve our understanding of the effect of these spaces on
welfare, with applications to zoos and other captive situations.
Space complexity and enrichment
The attributes of an enclosure would seem to be an essential element in Vicino & Miller’s
(2015) requirement that animals have quality spaces to express species-specific behavior.
In this regard, space complexity has indeed been shown to be important to the welfare of
elephants in zoos. Scott & LaDue (2019) examined the behavior of two elephants in three
different treatments: a small simple space (with a pool and shade structures), a small
complex space, and a large complex space (the latter two with a pool, shade structures,
elevated feeders, and varied substrate). Results indicated an increase in foraging and
self-maintenance and a decrease in time spent stationary in both the small and large
complex spaces, underscoring the importance of space complexity. Scott & LaDue (2019)
determined that increased exhibit complexity was sufficient to significantly improve
behavioral diversity, overall activity levels, and other behaviors indicative of positive
welfare, leading them to conclude that complexity should be prioritized over space (see
also DiVincenti, McDowell & Herrelko, 2023). However, the authors’own results show that
activity and behavioral diversity were highest in the large complex space. Increased
investigatory behavior was significantly higher in only the large complex yard, with
stereotypic behavior decreasing “drastically”in that condition. This indicates that the
combination of space and complexity achieved even more impressive results than did
complexity alone. Atkinson & Lindsay (2022) suggest that more expansive spaces, with
varied topography, natural substrates, and natural vegetation for foraging, can better
provide the level of environmental complexity necessary to stimulate natural behaviors
and provide choice, autonomy, and diversity of experience. A similar conclusion was
reached by Brown et al. (2020), who noted better elephant welfare in enriched, less
constricted, and more stimulating environments.
Creating space complexity can include the addition of various forms of enrichment to
an enclosure in order to promote the expression of important behaviors (e.g., foraging, self-
maintenance) and provide opportunities to engage in exploration, play, and problem
solving, as well as exercise choice (Hoy, Murray & Tribe, 2010;French, Mancini & Sharp,
2018;Greco et al., 2016b). Importantly, in their natural habitat, animals use their cognitive
skills to overcome problems that may directly or indirectly affect their survival.
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 7/41
Unfortunately, this type of problem solving has historically been absent in captivity
(Meehan & Mench, 2007). Only in more recent years has greater focus been placed on
more cognitive types of enrichment, including time-delay puzzle feeders, high tech
enrichment devices, and insightful problem solving tasks (Foerder et al., 2011;Highfill
et al., 2016;Krebs & Watters, 2017;French, Mancini & Sharp, 2018;Barrett & Benson-
Amran, 2020). Such cognitive enrichment, especially when species-appropriate abilities are
stimulated, appears to provide some positive behavioral benefits by increasing the animals’
interest in their environment (Krebs & Watters, 2017;Holland, 2018). Nevertheless, the
long-term benefits of such enrichment remain unclear. Furthermore, cognitive enrichment
may be provided infrequently in zoos, with keepers perceiving that semi-permanent and
permanent exhibit features (e.g., pools, logs, scratching areas, puzzle feeders) are more
important than cognitive enrichment (Hoy, Murray & Tribe, 2010;Greco et al., 2016b).
Greco et al. (2016b) found that problem-solving opportunities were components in the
enrichment programs of 97% of the 63 zoos they examined; however, these opportunities
were provided infrequently. In fact, the frequency of problem-solving enrichment was so
low that Greco et al. (2016b) were unable to test its effects in their welfare models. Such a
low frequency may be attributed to the time required to prepare and distribute enrichment,
as opposed to feeding enrichment, tactile enrichment, and human-animal interactions
(Hoy, Murray & Tribe, 2010).
There are few studies on the effects of enrichment for elephants, with most of them
focused on feeding enrichment (Greco et al., 2016b). As such, more research is necessary in
this area. Just as importantly, zoos must focus on the suite of enrichment options available
to them, especially in the area of problem-solving enrichment. Impediments to the
provision of enrichment include conflicting priorities, lack of available time, and
uncertainty about which enrichment practices are most effective (Hoy, Murray & Tribe,
2010;Tuite et al., 2022). This indicates the need for more support at all staff levels and for
increased resources to allow for the effective implementation and evaluation of enrichment
(Hoy, Murray & Tribe, 2010).
Exercise
Vicino & Miller’s(2015) third opportunity to thrive is that the animal should have an
environment that promotes good health. Certainly, an important welfare issue for
elephants is the amount of exercise they can experience, which is often measured by
distance traveled (Holdgate et al., 2016). Estimates of walking distances in nature vary by
age and sex (Slotow & van Dyk, 2004), season (Loarie, van Aarde & Pimm, 2009), and
resource availability (Gadd, 2002). Nevertheless, ~8–12 km/day are normal, with much
greater distances (up to ~50 km/day) being common (Wall et al., 2013;Miller, Hogan &
Meehan, 2016). Zoo-based studies of walking in elephants do not use uniform outcome
measures, making comparisons to natural habitat studies difficult. At the San Diego Zoo
Safari Park, Miller, Andrews & Anderson (2012) and Miller, Hogan & Meehan (2016)
estimated an average walking distance of 8.65–9.82 km/day for African elephants.
Similarly, Brady, McMahon & Naulty (2021) estimated Asian elephants traveled 9.35
km/day at the Dublin Zoo (enclosure size: 8,500 m
2
). Rowell (2014) calculated a distance of
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 8/41
9.05 km over an 18-hour period at the Royal Melbourne Zoological Gardens (enclosure
size: 5,143 m
2
). Holdgate et al. (2016), who gathered data on both African and Asian
elephants across 30 North American zoos, concluded that elephants walked only a distance
of 5.3 km/day, far shorter distances than in the wild. In general, the larger the enclosure,
the greater the opportunity for purposeful walking. Importantly, Holdgate et al. (2016) also
state that the range of exhibit sizes in the study population may not have been sufficient to
show the effect that very large areas can have on walking distances, and that elephants
might walk more if provided larger enclosures than are currently available in North
American zoos (cf., Meehan et al., 2016b). Holdgate et al. (2016) further determined that,
overall, the distances elephants walked in zoos were influenced most significantly by
feed-related factors. However, Hacker, Miller & Schulte (2018) note that Holdgate et al.
(2016) compared walking across institutions and not within the manipulated space of one
facility. In their own study, Hacker, Miller & Schulte (2018) manipulated space and food in
different conditions: access to two yards with food (Both); access to one yard with food
(Half); access to both yards with food in only one (Both/Half). They then measured
walking distances and behavior among elephants belonging to different dominance
groups. Increased walking distances for middle-ranked African elephants and a significant
correlation between the change in behavioral diversity across the Both and Half
treatments, along with dominance ranking, led the authors to conclude that both food and
space impact elephant walking and behavior at their institution. More clarity is needed to
assess the importance of space relative to food and how it affects walking distances.
Although the functional need for walking appears to be reduced in zoos due to the
provision of social and nutritional resources, ~60 million years of evolution has provided
Proboscidea with a range of anatomical and physiological specializations for long distance
living (Shoshani, 1998;Poole & Granli, 2009). For example, elephant foot morphology
allows them to load the most lateral aspect of their feet when walking which, along with
decreasing pressure below the foot’s fat pad, helps them maintain foot health
(Panagiotopoulou et al., 2016). This locomotion mechanism does not work well for
elephants housed in small enclosures with hard substrates (Panagiotopoulou et al., 2016).
The exercise elephants obtain by walking is also a crucial component of an enriched
environment because it supplies the brain with oxygenated blood, increases the
effectiveness of the immune system, and enhances an animal’s cognitive abilities (Jacobs
et al., 2021), while also providing metabolic benefits (Morfeld & Brown, 2017). Finally,
Holdgate et al. (2016) contend that walking is important because it supports exploratory
behavior and its information-gathering function may be rewarding outside of the
acquisition of resources.
Clearly, more research is required to determine the relationships between walking,
space, food, and social conditions for elephants in zoos. However, the lack of significantly
larger enclosure sizes will continue to constrain such investigations. As previously stated,
research in non-zoo facilities with larger, more complex spaces could enhance our
knowledge, potentially improving captive elephant welfare or helping to determine
whether elephants should be kept in captivity at all.
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 9/41
Sensory experience
Estimates of elephants’walking distances in zoos often miss a critical element: how the
captive elephant’s sensory experiences while walking differ from those of a free-ranging
elephant whose sensory environment is composed of a broad and often-changing variety
of sounds, smells, sights, and tactile and taste sensations. In nature, elephants exist in
different types of large, dynamic ecosystems (e.g., forests, open savanna, wet marsh, and
desert; Clubb & Mason, 2002), where they interact with diverse ecological features and
collect information about the physical and social environment. In captivity, sensory
experiences are largely predicted by the temporal and spatial features of their enclosures,
which are relatively limited and unchanging, and the enrichment provided within these
limited spaces (Lucas & Stanyon, 2017). Elephants in zoos typically are confined to one or
more outdoor yards, smaller holding areas, and/or a barn with individual and/or group
stalls (Lucas & Stanyon, 2017). Outdoor enclosures may contain a variety of natural and
artificial features such as soil and hard substrates (e.g., concrete), water features, wet and
dry wallows, and (concrete) rockwork or tree features to accommodate maintenance
behaviors (Clubb & Mason, 2002;BIAZA, 2019;AZA, 2021b). Note that concrete substrate/
rock/tree features challenge Vicino & Miller’s(2015) requirement that the opportunity to
self-maintain includes substrate that is species-specific. If sensory stimulation via
exploratory behavior and information-gathering in the captive environment is indeed
rewarding in itself (Holdgate et al., 2016), more diverse and natural surroundings with the
opportunity for more varied sensory experiences may be important to improving elephant
welfare. Facilities providing this type of environment currently include three Global
Federation of Animal Sanctuaries accredited elephant sanctuaries (two in the U.S. and one
in Brazil) and the AZA accredited White Oak Conservation Foundation in Florida. For
example, the elephant area at White Oak measures 68.8 km
2
, encompassing forest, open
grasslands, ponds, and wetlands, and a variety of plant (food) species (White Oak
Conservation, 2022). The Elephant Sanctuary in Tennessee spans 12.4 km
2
and features
spring-fed lakes, pastures and woodlands, and natural forage (The Elephant Sanctuary in
Tennessee, 2024).
Insofar as human visitors are another prominent feature of the zoo environment, they
are also part of an elephant’s sensory experience. Decades of research indicate that the
effect of zoo visitors can be negative, neutral, or positive in terms of animal behavior and
welfare (Hosey & Melfi, 2014;Sherwen & Hemsworth, 2019). Species-specific differences,
the nature of the visitor interactions, enclosure design, and individual animal temperament
may contribute to the variation in zoo animal responses (Sherwen & Hemsworth, 2019).
Visitor effects on elephants are also mixed, as are the facilities and conditions under which
they were studied. Based on research at the St. Louis Zoo, Krishnan & Braude (2014)
concluded that large audiences could serve as a source of behavioral enrichment, as
indicated by decreased stereotypies and the elephants’use of space. However, their
definition of a “high”crowd size was five or more people and “low”as fewer than five,
raising the question of whether their methodology was sensitive enough to support their
conclusion. Manning et al. (2023) studied elephants in a South African tourism park that
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offered human-elephant interactions (e.g., walks, feeding); observations were conducted
before, during, and after COVID pandemic closures. They concluded that changes in
behavior, including elevated self-directed behaviors (a novel indicator of anxiety in African
elephants), demonstrated that returning tourist numbers, whether high or low, were
stressful for the elephants. In examining public feeding of elephants in a zoo, Fernandez,
Upchurch & Hawkes (2021) suggested that public feedings may function as enrichment for
some elephants. Although the study was limited, the authors found that public feedings
appeared to result in increased social activity and a decrease in stereotypies (only one
elephant engaged in the behavior regularly) when compared with nonpublic feeding days
for two of three elephants. All three elephants showed increased foraging and were more
active in the period after a public feeding session. Williams et al. (2023) found that
elephants had positive responses to visitors more frequently than would be expected by
chance; however, they noted that enclosure design may reduce the negative impact of zoo
visitors on elephants because of the necessity of keeping a safe distance between visitors
and elephants. Although Quadros et al. (2014) did not specify elephants in their study of
the effects of visitor noise on 12 mammal species, they found significant behavioral
differences at the individual level. They concluded that the noise generated by zoo visitors
negatively affects the welfare of individual animals, especially when noise amplitude
exceeded 70 dB(A). Given the popularity of elephants in zoos, and the noise that can be
generated by the public (especially in indoor spaces), further study is clearly required to
determine whether and in what ways such human interaction affects elephant welfare
across different exhibit designs.
Caretakers represent another human facet of an elephant’s environment. Because
elephants are highly managed, keepers are essential contributors to elephant welfare
(Carlstead, Paris & Brown, 2019), an important aspect of Vicino & Miller’s(2015)
opportunity for optimal health. Elephants typically spend just over 50 percent of their
daytime hours under behavioral control in managed activities (e.g., exercise sessions, foot
and skin care, training; Greco et al., 2016a). There appears to be an inverse relationship
between time spent with keepers and an elephant’s rate of stereotypy, even outside of time
spent in keeper-directed activities. Greco et al. (2016a) attribute this to the social
relationships that elephants form with their keepers. Keepers may also benefit from these
relationships, as the stronger the bond felt by keepers, the less likely they were to report
dissatisfaction with their jobs (Carlstead, Paris & Brown, 2019). However, keepers
generally appear to develop stronger bonds with Asian rather than African elephants,
which is reflected in job satisfaction measures (Carlstead, Paris & Brown, 2019).
Management and housing differences may account for such measures (Carlstead, Paris &
Brown, 2019) because Asian elephants are managed for a significantly greater proportion
of their day than African elephants, who tend to be more independent (Greco et al., 2016b).
On average, African elephants spend more time in unique environments, and experience
greater total space and more outdoor space than Asian elephants (Meehan et al., 2016a).
Bonds between keeper and elephant may be related to welfare benefits for both. Carlstead,
Paris & Brown (2019) found that positive keeper attitudes were associated with lower mean
serum cortisol concentrations in elephants, suggesting that good keeper-elephant
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relationships lower stress responsiveness in elephants. In the future, zoos could
substantially expand exhibits for Asian and African elephants, potentially giving the
animals greater autonomy and requiring less keeper-managed time. This may call for
reassessing the nature of keeper-elephant relationships in order to maintain a beneficial
relationship for both keepers and elephants. Another important area of reassessment has
been the end of bullhook use in AZA zoos (AZA, 2022) and the phase-out of these devices
in EAZA facilities (EAZA, 2019), as their use presents serious challenges to the safety and
well-being of both elephants and keepers (Wilson et al., 2015).
Because the study of keeper-elephant relationships has received little attention in zoos
(Carlstead, Paris & Brown, 2019), more research in this area is necessary. Research that
focuses on the attitudes and beliefs of keepers relative to welfare measures in elephants
could contribute to positive welfare for elephants and ensure that keeper-elephant
relationships are mutually beneficial (Carlstead, Paris & Brown, 2019).
Sociality
Facilitating appropriate social structures for captive elephants is a particular challenge for
Vicino & Miller’s(2015) provision that the opportunity to express species-specific behavior
requires appropriate social groupings. Free-ranging elephants tend to live in matriarchal,
multi-generational family groups of two to 10 adult females and their offspring (Sukumar,
2006;Vance, Archie & Moss, 2009;de Silva, Schmid & Wittemyer, 2017). Elephant family
groups share a fission-fusion structure, separating and merging with larger groups of up to
several hundred elephants (Poole & Moss, 2008;de Silva, Ranjeewa & Kryazhimskiy, 2011).
In nature, female elephants remain with their natal herd, forming strong lifelong bonds
with related females, although family fissions are also common (Garai, 1992;Sukumar,
2006;Poole & Moss, 2008). Males differ in that they remain with their family group until
sexual maturity, when they disperse (Lee et al., 2011). They nevertheless maintain complex
social ties with conspecifics of all ages and both genders (Hartley, Wood & Yon, 2019).
Historically, captive elephants have often been limited to small groups of mostly
unrelated adult females with very few infants or juveniles (Clubb & Mason, 2002;Rees,
2009), making the inability to replicate natural social structures an area of concern for the
welfare of elephants in zoos (Williams et al., 2019b). Current research suggests that captive
elephants should be held in related, multi-generational groups for optimal welfare
(Williams et al., 2019b;Finch et al., 2020;Harvey et al., 2018;Hartley & Stanley, 2016). In
North America, only 20% of the 226 adult elephants in U.S. zoos studied by Meehan et al.
(2016a) had the opportunity to interact with young elephants, albeit an absence of calves in
a group does not necessarily lead to poor welfare (Williams et al., 2019b). Currently, zoo
standards allow for as few as three or four elephants (AZA, 2021b;BIAZA, 2019) and some
zoos continue to house females singly (AZA, 2021a). The AZA’s three-elephant minimum
does not specify that all elephants must be females, which can contribute to isolating
female elephants (e.g., two males housed separately from one female), or even the same
species. Schmidt & Kappelhof (2019) report that most of the female reproductive elephants
in the Asian Elephant European Association of Zoos and Aquaria Ex situ Programme
(EEP) are being held in family groups, an improvement over previous years. However, in
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general, there has been uneven progress in increasing mean group size for both Asian and
African elephants across North American and European zoos, with significant increases
found only for African elephants in North America (Rees, 2021). In North American zoos,
mean group sizes remain at 4.45 and 3.3 for African and Asian elephants, respectively
(Rees, 2021). Although Williams et al. (2019b) did not find a statistically significant link
between group size and prosocial behavior, they observed that the largest social group with
the greatest number of calves was the most socially interconnected. Other recent studies
have found more affiliative behaviors and fewer aggressive behaviors among related
elephants (Harvey et al., 2018;Finch et al., 2020), supporting the recommendation for
keeping elephants in related, multi-generational groups to optimize welfare. Using
free-ranging elephants as a model for structuring elephant groups in zoos has several
benefits, including promoting and facilitating social learning and natural social behaviors,
reducing abnormal behaviors and stereotypies, and improving health, welfare, and
reproduction (Hartley, Wood & Yon, 2019). However, to hold the greater number of
elephants that comprise multi-generational groups, zoos would require far larger and more
complex facilities. This presents a significant challenge due to the space and resources that
would be required.
The social environment has a considerable impact on stereotypic behavior rates, an
important indicator of compromised welfare (Greco et al., 2016a,2017). Spending more
time with larger numbers of conspecifics and the amount of time spent with juveniles is
associated with reduced stereotypy rates, whereas being housed separately increases
stereotypic behavior (Greco et al., 2016a). Inter-zoo transfers also increase the risk because
they can be disruptive to social groups and break important social bonds (Clubb & Mason,
2002;Armstrong & Johnson, 2021). Transfers are usually for breeding purposes,
coordinated through programs such as the Species Survival Plan that AZA accredited zoos
have adopted to promote genetic diversity (Rees, 2011). However, elephants can also be
moved between facilities as a result of space limitations, sex of offspring (Williams et al.,
2019b), or exhibit closure. The transfer of group members can affect social stability and
limit long-term success in zoo social groups (Williams et al., 2019b). As many as 80% of the
elephants in North American zoos in 2012 had experienced at least one inter-zoo transfer
(Prado-Oviedo et al., 2016). Clubb et al. (2008) found that inter-zoo transfers lessened
Asian elephant survivorship, an effect that lasted four years post-transfer, and Asian calves
removed from their mothers at a young age tended to have poorer outcomes. Considering
the complexity and importance of elephant social ties, it would be important to study the
effects of transfers on elephants based on age, sex, and species.
Male elephants pose a particular challenge in captive facilities due to their strength,
social needs, aggressiveness, and strong sexual and competitive motivations (Lee & Moss,
2009;Hartley, Wood & Yon, 2019). The proportional increase in the captive male
population in recent years presents an additional challenge. Going forward, the number of
males born will exceed the number that can be maintained in breeding groups and housing
will be needed to accommodate multiple groups of males (Readyhough et al., 2022). In
2017, males made up only 21% of the Asian elephant population in North America but will
eventually approach 50% (LaDue et al., 2022b), requiring greater consideration of their
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physical and social needs and living space. Schmidt & Kappelhof (2019) suggest that Asian
elephant husbandry guidelines in Europe may need to be redefined to, for example,
encourage zoos to hold male offspring longer. Still, more space would be needed to hold
males. They also suggest potentially requiring zoos to restrict breeding to keep the number
of males manageable.
Increasing evidence indicates that male elephants display extensive social behaviors that
rival the complexity of that of females (LaDue et al., 2022b). Despite their social nature,
males are typically held separately from females and other males although some zoos have
integrated adult males into social groups. In North America and Europe, the majority of
males are kept at zoos with females but no other males, restricting social learning from
older males and the development of appropriate social and reproductive behaviors
(Hartley, Wood & Yon, 2019). Although the importance of sociality for male elephants is
stressed by some (LaDue et al., 2022b;Readyhough et al., 2022), and although there are
welfare benefits from social interactions (e.g., reduction in stereotypies, Readyhough et al.,
2022), progress appears to be slow. Some U.S. and European zoos have created all-male
“bachelor”groups in response to the evidence for male sociality and the need to provide
space for an increasing number of captive males (Hartley, Wood & Yon, 2019;Readyhough
et al., 2022). In North America, there are currently two zoos holding bachelor groups
(AZA, 2019,2021a); in Europe, there are nine (Schmidt & Kappelhof, 2019). However,
Hartley, Wood & Yon (2019) caution that the focus of these groups should be on the social
development of the elephants rather than on creating bachelor groups as a convenient
solution to housing males. Subadult males of similar age and experience level who are held
together in bachelor groups are at risk of developing abnormal behaviors or a limited
behavioral repertoire due to the absence of social learning from mature males and family
groups, including failure to learn reproductive behaviors (Hartley, Wood & Yon, 2019).
Mixed-age bachelor groups that include a mature male may facilitate social learning
(Readyhough et al., 2022). The social makeup of bachelor groups is subject to change, as
males may be moved more often for breeding purposes (Schmidt & Kappelhof, 2019),
potentially breaking social bonds. The effects of such moves on individual males and
groups is an area for future study. Importantly, the creation of bachelor groups is a
relatively new development in zoos; as such, it is too early to determine if it will be feasible
over a long period of time (Schmidt & Kappelhof, 2019). Also, many zoos prefer to keep
their male with a female group for his well-being (Schmidt & Kappelhof, 2019). Clearly,
providing appropriate housing and social conditions for males will continue to be a
challenge as the number of male elephants continues to increase.
Optimizing the social lives of captive elephants may involve a variety factors: increasing
group size (Lasky et al., 2020), facilitating highly related multi-generational groups
(Hartley & Stanley, 2016;Harvey et al., 2018;Williams et al., 2019b;Finch et al., 2020;
Armstrong & Johnson, 2021), integrating males and females (Hartley, Wood & Yon, 2019;
Lasky et al., 2020), developing fission-fusion housing (Schmidt & Kappelhof, 2019), and
creating mixed-age bachelor groups (Hartley, Wood & Yon, 2019;Readyhough et al., 2022).
These improvements all require significant resources, including larger, more complex
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environments that allow for the management of males and females (Hartley, Wood & Yon,
2019). At the same time, changes must be carefully approached and science-based. For
example, while fission-fusion housing strategies are suggested as a way to improve welfare,
uncontrollable social changes and social frustration could generate locomotor stereotypies
(Greco et al., 2017). More research is necessary to determine a management strategy that
would enable fission-fusion through free choice of social associations and indoor/outdoor
locations on a round-the-clock basis. Although the opportunity for appropriate social
contact is considered to be more important for welfare than space (Williams et al., 2020),
Veasey (2020) cautions that zoos with limited space will face challenges in addressing such
important behaviors as elephant sociality, feeding, and foraging. Certainly, greater capacity
is required to hold large or growing groups of elephants and to accommodate males
(Hartley, Wood & Yon, 2019;Schmidt & Kappelhof, 2019). In addition, there is a need to
better understand captive elephants’social networks and social behavior over longer
periods of time and how social changes affect individuals and groups (Williams et al.,
2020). The resource-intensive conditions (e.g., space, finances, personnel) required to
facilitate appropriate social conditions for captive elephants could stand in the way of
optimizing welfare and could determine whether elephants should be kept in captivity.
Feeding challenges
Vicino & Miller (2015) stress that animals should have the opportunity for a thoughtfully
presented, well-balanced diet. For elephants, feeding involves much more than meeting
dietary requirements. It often involves cognitive and physical challenges that are essential
to an elephant’s behavioral ecology and well-being. Foraging involves movement,
exploration, and choosing areas in a landscape that hold high foraging opportunities, then
homing in on preferred foods (Das, Kshettry & Kumara, 2022). The handling of food may
involve manipulation (e.g., prying bark from a tree, digging, kicking dirt off of grass roots)
before consumption (Poole & Granli, 2009). Feeding is often done in concert with the
family group, making it a social activity. Individual elephants vary their diets based on
availability, preferences, and physiological needs (Gill et al., 2023). Free-ranging elephants
are highly diverse feeders, consuming more than 100 seasonally and geographically varying
food species (e.g., grasses, trees, bark, roots, fruits, and aquatic plants; Dierenfeld, 2006;
Campos-Arceiz & Blake, 2011;Das, Kshettry & Kumara, 2022). As large-bodied herbivores,
elephants naturally spend 60–80% of their waking hours foraging over long distances
(Poole & Granli, 2009). In contrast, zoo diets tend to be more restricted in terms of the
variety of foods, are seasonally invariant, and (often excessively) high in calories (Carneiro
et al., 2015;Schiffmann et al., 2018). Diets for elephants in zoos generally consist of dried
forage, usually hay, supplemented with commercial concentrate feed pellets, vitamins,
fruits, and vegetables (Dierenfeld, 2006). Feeding schedules tend to be temporally
predictable with high spatial predictability and only moderate variation in feeding
methods (Greco et al., 2016b), although some zoos try to diversify the way animals are
fed as a form of limited enrichment (e.g., puzzle/feeder balls, elevated nets with hay;
Ramírez et al., 2023). Not unexpectedly, a more varied and unpredictable feeding regime
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enhances well-being in captive elephants by promoting walking (Holdgate et al., 2016).
Nearly three-quarters of the elephants across 65 AZA accredited North American zoos
were determined to be overweight or obese, putting them at risk of health conditions such
as ovarian acyclicity (Morfeld et al., 2016), joint disease/osteoarthritis (West, 2006), foot
ailments, and gait problems (Roocroft & Oosterhuis, 2001).
Timing, frequency, and methods of food provision are key components of elephant
feeding programs (Greco et al., 2016b). These areas nevertheless require continuous
attention to avoid temporal and spatial predictability. As with enrichment, feeding
programs require considerable keeper time, resources, and biologically informed policies.
Including browse in the diet appears to be beneficial for elephant welfare as it increases
opportunities for foraging behaviors and the amount of time spent feeding, decreases
inactivity, and allows elephants to engage in naturalistic feeding behaviors (e.g.,
manipulating branches, stripping leaves and bark; Stoinski, Daniel & Maple, 2000;Lasky
et al., 2020), although it may not decrease stereotypic behaviors (Lasky et al., 2020). In
highlighting the importance of foraging, AZA and BIAZA guidelines state that browse
should be made available to elephants; however, neither organization specifies the amount
of foraging time or type of foraging opportunities (Veasey, 2020). This is an area that must
be addressed in order to standardize feeding practices and improve elephant welfare.
CURRENT HEALTH AND WELFARE ISSUES
Although Vicino & Miller’s(2015) opportunity for optimal health would seem to be met
with the presence of constant veterinary care, questions remain about whether the captive
environment actually decreases the likelihood of elephants being healthy insofar as the
welfare of elephants is multidimensional. A variety of variables may factor into the clinical
problems elephants experience in the captive environment. In this section, we describe
what is known about the current mental and physical health of captive elephants. We also
discuss the impact that chronic stress has on mental and physical health, so that behavioral
abnormalities and opportunistic infections become prevalent, sometimes leading to
increased mortality. All these factors contribute to a generally problematic clinical
situation for captive elephants.
Brain and behavior
Stereotypies
A prevalent, observable abnormality (Bacon, 2018) in captive but not free-ranging animals
is stereotypic behavior (Mason & Latham, 2004;Mason & Rushen, 2008). Stereotypies in
elephants typically take several forms: whole body (e.g., limb-swinging, back and forth
movement), locomotor body (e.g., pacing, repeatedly walking in the same pattern),
self-directed (e.g., limb or head banging, self-stimulating behaviors), and oral (e.g., trunk
sucking, bar biting) (Glaeser et al., 2021). Between ~47% and ~ 85% of elephants in zoos
exhibit stereotypies, which can consume up to ~20% of the animal’s daily activity (Mason
& Latham, 2004;Mason & Veasey, 2010). Greco et al. (2016a) determined in North
American zoos that, after feeding, stereotypic behavior was the second most commonly
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performed behavior in elephants. Stereotypies are not just behavioral. They reflect an
underlying dysregulation in the motor control systems of the brain, that is, a form of brain
damage that leads to excessive, purposeless movements (Jacobs et al., 2021).
In an attempt to alleviate stereotypies, zoos often provide directed types of enrichment
(Ramírez et al., 2023) which, unfortunately, remain insufficient as not all types of
enrichment are equally effective (Law & Kitchener, 2017;Lyn et al., 2020). It has indeed
been estimated that zoo enrichment is only effective in significantly reducing stereotypies
53% of the time (Swaisgood & Shepherdson, 2005). More recent research found that the
frequency of stereotypic behavior decreased in Asian bull elephants when they were
housed socially with other bulls rather than housed alone (Readyhough et al., 2022). It
should nevertheless be noted that enrichment that is transient can actually create more
stress and frustration for the animal (Latham & Mason, 2010). Zoo enrichment thus runs
the risk of being an expedient attempt to treat the specific psychological/behavioral/neural
problems that arise from the captive environment itself (Jacobs et al., 2021), and may fall
well short of the broad-spectrum enrichment provided by the natural habitat (Swaisgood &
Shepherdson, 2005;Morgan & Tromborg, 2007). With a brain that is among the largest on
the planet, at ~5,000 grams (Manger et al., 2009;Manger, Spocter & Patzke, 2013),
elephants are evolutionarily adapted to flourish in an extremely complex, stimulating
environment, which traditional captive facilities cannot replicate. Several researchers have
suggested that providing complex spaces and enhancing the social environment may
reduce stereotypies (Greco et al., 2017;Glaeser et al., 2021;Scott & LaDue, 2019).
Nevertheless, a more comprehensive, a priori solution would be to not put elephants in a
captive environment that leads to stereotypic behavior.
Physical health
Nutrition and metabolism
Elephants ingest a large variety of foods in the wild to meet their nutritional needs
(Dierenfeld, 2006;Campos-Arceiz & Blake, 2011;Das, Kshettry & Kumara, 2022), whereas
captive diets are frequently monotonous and characterized by a lack of essential vitamins
and minerals (especially vitamin E and iodine; Dierenfeld, 2006), a deficiency of fiber, and
excessive calories (Tsuchiya et al., 2023). Combined with lack of exercise, the high caloric
diet contributes substantially to widespread obesity among captive elephants (Gupta,
Sharma & Swarup, 2015;Brown et al., 2019;Tsuchiya et al., 2023). Many zoos have added
browse (including bamboo) to increase dietary fiber and as enrichment (Tsuchiya et al.,
2023) as it can reduce obesity and colic (Hatt & Clauss, 2006). Of 240 elephants examined
in North American zoos, 74% were overweight and 34% clinically obese (Morfeld et al.,
2016). Obesity in elephants may be associated with poor health and reproduction (Morfeld
et al., 2014). As in North American zoos, condition scores for the majority of elephants in
European zoos indicated they were overweight (Schiffmann et al., 2018). Insofar as
optimizing elephant nutritional intake for captive elephants can be problematic
(Schiffmann et al., 2018), zoo diets remain a challenge.
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Skin and musculoskeletal health
One third of elephants with medical conditions in North American zoos have skin issues
(e.g., lesions, overgrowth of dead skin, parasites, sunburn, pressure sores; Fowler, 2006a;
Mikota, 2006;Brown et al., 2019), although the prevalence of skin lesions in North
American populations is reported to have decreased in the last 20 years with improved
bathing and skin care protocols (Edwards et al., 2019). An elephant’s skin requires daily
care, which is achieved in the natural habitat by regular dust and mud bathing, abrasion,
and occasional bathing (Lehnhardt, 2006). To this end, the AZA now requires that captive
elephants have access to scratching posts and opportunities for bathing, dusting, and
wallowing (Edwards et al., 2019;AZA, 2021b).
Foot disease is another common ailment of captive elephants. Early estimates suggested
that ~50% of captive elephants suffer from foot ailments (e.g., hyperkeratosis, cracked
nails, infections), often from unsanitary or overly wet conditions (Fowler, 2001,2006a).
However, one study across 13 U.K. zoos found that more than 80% of elephants
demonstrated foot disease, with over 85% exhibiting gait abnormalities (Harris, Sherwin &
Harris, 2008). More recently, Miller, Hogan & Meehan (2016) suggested that
approximately two-thirds of elephants in the U.S. had foot issues. In a post-mortem
imaging study, Regnault et al. (2017) found that every captive elephant (n= 21) they
examined exhibited foot pathology. Wendler et al. (2020) state that rather than being the
result of one or two factors, poor foot health may indicate a generally poorer husbandry
system. They found that more advanced husbandry conditions (e.g., large areas, high
proportions of sand substrate) were associated with each other and better foot scores. More
limited conditions (e.g., more time spent indoors, higher proportion of hard substrate)
were associated with each other but also indicated worse foot scores.
Deeper musculoskeletal ailments are also commonplace in captive elephant
populations, including osteoarthritis, which regularly occurs prematurely in captive
elephants. Such ailments are associated with pain and joint stiffness, inability to
stand, and sometimes require euthanasia (Issa & Griffin, 2012;Buckwalte et al., 2013).
Miller, Hogan & Meehan (2016) attributed musculoskeletal disease to time spent on hard
substrates (e.g., concrete, packed soil) and space experienced in indoor/outdoor exhibits
(“space experience”is defined as the measure of space weighted by amount of time spent in
that space). Although the authors found only 11.1% of the elephants in their study
showed evidence of musculoskeletal problems, they state that the prevalence of
those abnormalities was likely underestimated due to lack of sensitive diagnostic
techniques.
Dental disease
African elephants use their tusks for many purposes (e.g., digging, carrying, sparring,
debarking trees; Weissengruber, Egerbacher & Forstenpointner, 2005;Dumonceaux, 2006).
Although both free-ranging and captive elephants are prone to tusk injuries (Steenkamp
et al., 2008), these injuries are particularly common in captive elephants, who frequently
encounter hard, unyielding materials (e.g., concrete, metal). Tusk injuries have been
documented in 31% of elephants across 60 North American zoos (Steenkamp et al., 2008).
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Injuries involving the pulp cavity can become infected and lead to necrosis and fatality
(Dumonceaux, 2006;Rose et al., 2018). Unlike carnivores, elephant molars are produced in
the back of the jaw and grow forward continuously. Molar fragments must be shed at the
front of the mouth with regularity to make room for the progressive movement. Access to
an appropriate diet, including adequate roughage, contributes to healthy molar shedding
(Asquith-Barnes et al., 2017). Unfortunately, molar tooth retention is a common dental
problem for captive elephants (Steenkamp, 2021). This can cause pain and reluctance to
eat, and frequently results in periodontal infection due to the impaction of food and
bacteria around the tooth. Oral cavity infections can cause chronic and painful
inflammation of the oral cavity (i.e., stomatitis). Another functional abnormality that
captive Asian elephants frequently suffer is malocclusion, which occurs when molar
fragments rotate abnormally (Steenkamp, 2021). These functional abnormalities can
contribute to complications (e.g., uneven tooth wear, pain, disruption of mastication),
including serious gastrointestinal disease and weight loss (Dumonceaux, 2006;
Steenkamp, 2021).
Digestive and gastrointestinal disease
It is now well understood that the gut microbiome of the elephant is impacted dramatically
by stress and by changes in environment, in particular captivity (Bo et al., 2023).
Numerous factors appear to be involved, including a lack of access to natural
environmental microbes, dietary changes, frequent antibiotic use, and psychological/social
stress (Bo et al., 2023). Unsurprisingly, gastrointestinal diseases are common in captive
elephants (Greene, Dierenfeld & Mikota, 2019). Poor dietary management, coupled with
lack of exercise, is a predisposing factor for colic (Khadpekar et al., 2020), especially in
older elephants with decreased gut motility and dental problems (Greene, Dierenfeld &
Mikota, 2019), which can progress to a life-threatening illness (Khadpekar et al., 2020).
Other gastrointestinal diseases include diarrhea, constipation, bloat, gastritis, and
occasionally intussusception or torsion. Infectious organisms are sometimes implicated in
gastrointestinal conditions, including Salmonella, Clostridium difficile, and gastrointestinal
parasites (Greene, Dierenfeld & Mikota, 2019).
Infectious disease
Captive elephants are particularly susceptible to Mycobacterium tuberculosis (TB) and the
elephant endotheliotropic herpesvirus (EEHV), which are highly contagious and can
manifest as latent infections (Mikota & Maslow, 2011;Fuery et al., 2018;Alkausar et al.,
2024). As with humans, TB is a deadly disease in elephants; however, unlike humans,
elephants are often poorly tolerant of anti-tuberculosis drugs and treatment is often
unsuccessful (Lyashchenko et al., 2006). TB was confirmed between 1994 and 2010 in 50
elephants in the U.S.—approximately 12% of the country’s captive elephant population
(Mikota & Maslow, 2011), with the actual number likely to be much higher because of
subclinical carriers (Greenwald et al., 2009). Captive populations, particularly Asian
elephants, are disproportionately affected by TB because of stress-induced
immunosuppression (Mikota, 2009).
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 19/41
Although EEHV has been documented in free-ranging elephants (Kerr et al., 2023), it is
particularly prevalent in captive and semi-captive conditions, especially in young,
physically stressed or injured, or immunocompromised Asian elephants (Schaftenaar
et al., 2010;Alkausar et al., 2024), including calves who have not received adequate
maternal antibodies (Hoornweg et al., 2021). In this regard, group size appears to be an
important variable insofar as larger groups increase the chance that calves will be exposed
to EEHV-shedding elephants at a time when the calves still have high levels of maternal
antibodies, in turn, protecting them from the virus (Hoornweg et al., 2022). This finding
may be particularly important for the zoo environment, where captive group size remains
low, reducing a calf’s chances for exposure while still protected by maternal antibodies
(Hoornweg et al., 2022).
Newly developed serological assays have shown that the prevalence of EEHV in captive
elephants is nearly ubiquitous and, therefore, the risk of exposure is inevitable (Hoornweg
et al., 2021). EEHV-HD (the haemorrhagic disease process associated with EEHV) is now
the leading cause of death for captive Asian elephant calves under 8 years old (Perrin et al.,
2021;Alkausar et al., 2024). It has killed over 100 captive and free-ranging elephants
around the world in just over 30 years (Long, Latimer & Hayward, 2015), including
12–17% of all Asian elephant calves born in Western zoos (Hoornweg et al., 2022). The
virus is presently responsible for 65% of all captive Asian elephant deaths in North
America (Titus et al., 2022). In calves, the peak period of EEHV risk coincides with the
weaning period (Perrin et al., 2021), with stressors contributing significantly to severe cases
of EEHV that progress quickly and become fatal (Kendall et al., 2016). Specifically, the
stress associated with social change triggered by the movement of animals between, into, or
out of herds poses the greatest risk for recrudescent viral shedding, subsequent infection,
and death by haemorrhagic disease in captive Asian elephant calves (Titus et al., 2022).
Although EEHV has been mainly associated with Asian elephants, recent cases among
captive African elephants have intensified concern about the susceptibility of this species to
EEHV. Prior to 2019, only five cases of clinical disease from EEHV infection had been
documented in African elephants. Since 2019, there have been at least seven EEHV cases in
North American zoos, with three fatalities (Pursell et al., 2021).
In addition, infection caused by Clostridium, Salmonella, and E. coli species of bacteria
are a frequent clinical challenge in captive elephants. Various Clostridium species are
implicated in the deaths of elephants in zoos, including the organisms that cause botulism,
as well as C. perfringens, C. difficule, and C. septicum (Hess, 2022). Salmonellosis tends to
follow stress-related depression of the immune system (Fowler, 2006b), a finding that
strongly suggests a negative relationship between captivity induced stress and immune
competence (Fowler, 2006c;Mikota, 2009;Schaftenaar et al., 2010).
Reproduction
Captive female elephants, because of stress and obesity, often enter prolonged periods of
estrus acyclicity (Hermes, Hildebrandt & Göritz, 2004;Edwards et al., 2015). Other
reproductive pathologies include a high incidence of ovarian cysts, and neoplasia (Clubb &
Mason, 2002;Hermes, Hildebrandt & Göritz, 2004;Brown, 2019). Captive females tend to
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 20/41
reach sexual maturity at an accelerated rate, both in terms of estrus onset and first
pregnancy (Lee et al., 2016). The accelerated rate of sexual maturity is often associated with
early reproductive senescence (Hermes, Hildebrandt & Göritz, 2004). Although rare in free
or semi-captive (i.e., less intensive confinement and social restriction) populations, captive
elephants suffer from a high rate of stillbirth, infant mortality, and infanticide, with a 20%
stillbirth/perinatal death rate in North American zoos (Taylor & Poole, 1998) and 21% in
European zoos (Perrin et al., 2021). Saragusty et al. (2009) found a skewed sex ratio (i.e.,
more males are born in zoos), and that the juvenile mortality rate in captive facilities is
almost double that in the wild. Indeed, captive Asian elephants are five to eight times more
likely to deliver a stillborn calf than elephants managed in extensive systems (e.g., logging
camps) in Asia (Clubb & Mason, 2002), potentially because of obesity (Taylor & Poole,
1998). It has been suggested that modifications to captive environments and husbandry
programs focused on enhancing social well-being, environmental complexity, nutrition,
and exercise would help to ameliorate the widespread reproductive dysfunction observed
in captive elephants (Brown, 2019).
Longevity, survival, and mortality rates
The elephant population in zoos is generally not sustainable without imports from the wild
(Wiese, 2000;Hutchins & Keele, 2006;Mar, Lahdenperä & Lummaa, 2012;Kurt, 2014) due
to the poor reproductive success and low survivorship of captive elephants, who suffer
from a reduced median lifespan as well as a higher mortality rate than their free-ranging
and semi-captive counterparts (Clubb et al., 2009). Schmidt & Kappelhof (2019), however,
report that the Asian elephant EEP (European Association of Zoos and Aquaria Ex situ
Programme) has become successful, with most demographic and genetic parameters
showing healthy numbers of Asian elephants in the population. However, limited data
exist on free-ranging Asian elephant lifespans, semi-captive Asian elephants used in the
logging industry in Myanmar have a reported average longevity of between 34–41.7 years,
with ~10% of females living to be over 60 years old (Clubb et al., 2008). Furthermore,
reports from across Asian range countries document animals living well into their 80s
(Mobasheri & Buckley, 2021). However, Asian and African elephants in zoos have a
median lifespan of between 16.9–18.9 years (Clubb et al., 2008), with captive born Asian
elephants having higher adult mortality rates than those born in the wild (Clubb et al.,
2008). For African elephants, average life expectancy in the wild is between 41–56 years,
with ~5% of individuals living to be over 65 years of age (Clubb et al., 2009;Lee et al., 2016).
Captive African elephants exhibit a mortality rate that is 2.8 times higher than their
free-ranging counterparts (Clubb et al., 2008). Scherer et al. (2023) examined historical data
to determine changes in the survivorship of elephants in American and European zoos, as
compared to findings by Clubb et al. (2008) that survivorship had improved for African
elephants in zoos since 1960, but not for Asian elephants. Scherer et al. (2023) also
determined that from 1960 to 2023, improvement in survivorship was significant for
African elephants. They found there was close to a significant improvement for Asian
elephants. Asian elephants generally had a higher survivorship than did African elephants.
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 21/41
Juvenile survivorship in zoos since 1960 did not change significantly; however, it was
higher in African elephants likely due to the effects of EEHV on Asian elephants.
A MORE GLOBAL PERSPECTIVE
Although the present review has focused primarily on Western facilities, the situation in
other countries, where there is often less regulation, is considerably worse, with
improvements even more urgently needed. For example, a visual assessment of 81 tourist
and temple elephants in India between 2004–2005 found significant physical ailments,
including 74% showing foot issues in the form of fissures, 20% of which were classified as
severe, and 43% displaying hyperkeratosis (Ramanathan & Mallapur, 2008). Vanitha,
Thiyagesan & Baskaran (2010) determined that temple elephants in Tamil Nadu, India,
spend less than an hour a day walking and exercising and are chained nearly 70% of the
time in a small space, raising concerns for foot disease, obesity, arthritis, and lowered life
expectancy (cf., Ramanathan & Mallapur, 2008). Among captive elephants in temple
systems in Tamil Nadu, India, the prevalence of stereotypies was documented at ~49% and
was positively correlated with the duration of chaining (Vanitha, Thiyagesan & Baskaran,
2016). In Thailand tourist camps, 57% of elephants exhibited stereotypies, with the rates
being highest in elephants between 4–10 years of age (Fuktong et al., 2021). Finally,
although accrediting organizations (e.g., AZA, BIAZA) strongly discourage general use of
free contact, the bullhook (or ankus), and prolonged chaining, such management practices
are still in use in facilities around the world. For example, Bansiddhi et al. (2019) reported
that use of the ankus is a welfare concern among elephants used for tourism; half of the
elephants studied had wounds, with most caused primarily by the ankus (e.g., abrasions,
lacerations, abscesses) but also knives (e.g., penetrating and incision wounds), scratches,
and pressure wounds. Captive elephants in Sri Lanka are also managed through
subjugation, with chaining and liberal use of the ankus (Fernando et al., 2011).
Unfortunately, government regulations are often inadequate to protect elephant welfare or
have not been effectively implemented or enforced (Fernando et al., 2011;Bansiddhi et al.,
2018;Baker & Winkler, 2020).
ANIMAL WELFARE IMPLICATIONS
In the present review, we have highlighted concerns that, after a preliminary review of the
literature, were determined to be important to elephant welfare in the captive setting. The
present overview indicates that, for elephants, there is a considerable mismatch between
the captive and natural environment, one that appears to negatively impact well-being in
captivity (Mason, 2010;Hosey, Melfi& Ward, 2020). Moreover, the natural, sociobiological
characteristics of elephants (e.g., the need for space, cognitive and social complexity, and
dietary practices) predict the welfare challenges summarized above (Clubb & Mason, 2007;
Miller, Andrews & Anderson, 2012;Pomerantz, Meir & Terkel, 2013;Hosey, Melfi& Ward,
2020;Mellor et al., 2021), outcomes that were outlined in Mason’s(2010) comparative
examination of species differences in response to captivity.
Whether zoos can provide for the needs of elephants is a question that has received
increasing attention with regards to environmental enrichment (Alligood et al., 2017;
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 22/41
Hosey, Melfi& Ward, 2020;Fernandez & Martin, 2021;Jacobs et al., 2021;Mellor et al.,
2021). The relationship between different forms of environmental enrichment and
well-being is not well understood and, whereas some directed enrichment methods may
appear to have a positive impact in specific ways (Ramírez et al., 2023), there is no evidence
to suggest it allows species like elephants to flourish in captive facilities (Meehan et al.,
2019). The effects of environmental enrichment can only be fully understood in the context
of valid and reliable methods of welfare assessment (Brereton & Rose, 2023). To that end,
there have been several recent advances in developing systematic evidence-based welfare
assessment methods for captive elephants (Meehan et al., 2019;Williams et al., 2019a,
2019b;Yon et al., 2019;Bansiddhi, Brown & Thitaram, 2020;Bansiddhi et al., 2020). In a
large-scale epidemiological study of 291 elephants across 70 North American zoos, the
Elephant Welfare Initiative underscored the importance of larger social groups for
elephant welfare (Carlstead et al., 2013;Greco et al., 2016a;DiVincenti, McDowell &
Herrelko, 2023). Another large scale, meta-analysis of United Kingdom zoos found the best
indicators for elephant welfare were reduced stereotypies, reduced glucocorticoids, and
improved body condition scores, followed by increased lying rest and positive social
interactions (Williams et al., 2018). Although these projects represent a step forward in
captive animal management, it is important to note that assessing welfare is not equivalent
to providing welfare or promoting well-being. It remains unclear just how extensively any
of these proposed welfare measures are employed. Of those listed above specificto
elephants, only Yon et al. (2019) actually states that the welfare measures have been
implemented. Therefore, proposed improvements in assessment techniques are only the
first step in addressing captive welfare issues and are not, by themselves, demonstrations of
improved well-being (especially if they are never implemented).
In captivity, it is exceptionally difficult to meet elephants’overall ecological needs, as
well as their individual needs (Armstrong & Johnson, 2021). Recently, some zoos have
reported improvements in welfare, often related to exhibit expansion and changes in
husbandry. These areas include increased movement (Glaeser et al., 2021), reduced
stereotypies (Finch et al., 2020;Glaeser et al., 2021), improved feeding strategies/
opportunities (Glaeser et al., 2021;Lasky et al., 2020) consideration of male social needs
(Readyhough et al., 2022), increased activity and outdoor time (Glaeser et al., 2021), and
end of bullhook use (AZA, 2022). However, for many zoos some of these improvements are
aspirational (e.g., bull groups-Hartley, Wood & Yon, 2019;Finch et al., 2020). Much of the
literature we have cited acknowledges existing shortcomings and areas where further
improvement is required. In fact, zoos continue to be limited by space and available human
and financial resources (Doyle, 2018), which also limits the extent to which they can
provide larger, more complex, and variable environments that allow elephants to engage in
a full suite of natural behaviors (e.g., fission-fusion), particularly as compared to elephant
range countries. It is unclear yet how zoo improvements will affect health and well-being
long-term, as certain problems persist (e.g., stereotypies, lack of natural foraging
opportunities, social group size and composition, male elephant housing, infectious
diseases, foot pathologies, and obesity). As noted by Pierce & Bekoff (2018), discussions of
animal welfare in zoos tend to focus on incremental improvements without addressing the
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 23/41
underlying problems that captivity presents; they consequently call for completely
changing the captive landscape.
From an ethical point of view, the deeper issue is whether elephants can ever thrive, not
simply survive, in captivity. This entails understanding not only how physically healthy
organisms are or how long they live, but how well individual animals live—the overall
quality of their life, their well-being. It includes such dimensions as the ability to exercise
autonomy (Vicino & Miller’s(2015) opportunity for choice and control) and be stimulated
by significant challenges in the environment. Current evidence suggests that, although
zoos can renovate existing enclosures with some physical and behavioral benefit(Lucas &
Stanyon, 2017), they generally cannot provide a sufficient facsimile of a free-ranging life to
allow captive elephants to thrive. Insofar as elephants cannot usually be released from a
zoo into a free-ranging natural environment as they do not have the necessary survival
skills, there are limited ethical options. Atkinson & Lindsay (2022) suggest that an
enclosure size of 1 km
2
or more of environmentally complex natural habitat in a warm
climate could provide captive elephants the chance for more fulfilling lives. Poole & Granli
(2009) offer a scenario for facilities 50–75 km
2
in size that would hold two to three family
groups (20 to 30 elephants to allow for the development of fission-fusion characteristics)
and adult males to create a naturally functioning population. They point out, however, that
the number of elephants would eventually outgrow the limitations of such a facility,
necessitating ethically unacceptable interventions such as transfers of individuals to other
facilities.
On a global scale, some countries are reevaluating whether they should keep elephants
in captivity or provide additional protections for captive elephants. In 2021, for example,
the United Kingdom began ongoing discussions on banning elephants in zoos because of
the challenges of providing them with a healthy environment (Aoraha, 2021;Atkinson &
Lindsay, 2022). Proposed legislation in Canada (i.e., Bill S-15, introduced in 2023) aims to
prohibit possessing, breeding, or impregnating elephants (and great apes) in captivity and
to prohibit using them for entertainment purposes (Senate of Canada, 2023). The ongoing
challenge of housing elephants in zoos is reflected in the fact that, according to AZA
regional studbooks for Asian and African elephants, the number of AZA accredited zoos
holding elephants in the U.S. appears to have dropped from 67 to 49 in the last decade.
Indeed, since 1991, 34 AZA accredited North American zoos have ended their elephant
exhibits (Table 1). They have done so for a variety of reasons (e.g., lack of space, funding,
lack of social opportunities, inability to provide for aging elephants, non-compliance with
AZA social group size standards). These cessations have resulted in the transfer of 52
elephants, with 31 initially transferred to other zoos (with two animals subsequently being
moved to a sanctuary) and 23 transferred directly to sanctuaries. If an elephant is healthy
enough to transfer, accredited sanctuaries represent a viable alternative. Although still a
form of captivity, authentic sanctuaries provide a permanent home and a larger, more
complex natural environment. In this regard, it was recently reported that stereotypic
behaviors in several captive African elephants reintegrated into the wild immediately
ceased upon their release (Pretorius, Eggeling & Ganswindt, 2023), but more research is
clearly needed on the welfare effects of moving elephants to a sanctuary setting. Accredited
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 24/41
Table 1 AZA accredited zoological facilities in North America that have terminated their elephant exhibits since 1991.
Zoological facility
1
Final year Elephant
2
Transfer to
3
Status
4
Sacramento Zoo (CA) 1991 F Asian (Winky) Detroit Zoo, then PAWS in 2005 d. 2017
Louisiana Purchase Gardens
and Zoo (LA)
1999 F Asian (Shirley) TES d. 2021
Mesker Park Zoo (IN) 1999 F Asian (Bunny) TES d. 2009
Henry Vilas Zoo (WI) 2000 F Asian (Winkie) TES d. 2017
Greater Vancouver Zoo
(CAN)
2003 F Asian (Tina) TES d. 2004
Chehaw Wild Animal Park
(GA)
2004 F African (Tange) TES alive
F African (Zula) TES d. 2009
San Francisco Zoo (CA) 2005 F Asian
(Tinkerbelle)
PAWS in 2004 d. 2005
F African (Lulu) PAWS d. 2024
Detroit Zoo (MI) 2005 F Asian (Winky) PAWS d. 2008
F Asian (Wanda) PAWS d. 2015
Lincoln Park Zoo (IL) 2005 F African (Wankie) Hogle Zoo d. euthanized shortly
after arrival
Gladys Porter Zoo (TX) 2006 F African (Ruth) Milwaukee Zoo alive
Abilene Zoo (TX) 2007 F African (Tanya) Cameron Park Zoo d. 2020
Philadelphia Zoo (PA) 2009 F African (Kallie) Pittsburgh Zoo’s Int’l Conservation Center, then
Cleveland Zoo in 2011
alive
F African (Bette) Pittsburgh Zoo’s Int’l Conservation Center alive
F Asian (Dulary) TES d. 2013
Brookfield Zoo (IL) 2010 F African (Joyce) Six Flags Wild Safari Adventure, NJ alive
Lion Country Safari (FL) 2010 F African
(Ladybird)
Greenville Zoo d. 2014
M African
(Bulwagi)
Disney’s Animal Kingdom in 2006, then Birmingham
Zoo in 2010
alive
F African (Mama) Dallas Zoo d. 2015
F African (Stumpy) Dallas Zoo d. 2012
Jackson Zoo (MS) 2010 F African (Juno) Nashville Zoo, then TNEC in 2015 d. 2015
F African (Rosie) Nashville Zoo, then TES in 2015 d. 2016
Central Florida Zoo (FL) 2011 F Asian (Maude) Zoo Miami d. 2013
Toronto Zoo (CAN) 2013 F African (Iringa) PAWS d. 2015
F African (Thika) PAWS alive
F African (Toka) PAWS alive
BREC’s Baton Rouge Zoo
(LA)
2013 F Asian (Bozie) Smithsonian’s National Zoo alive
Calgary Zoo (CAN) 2014 M Asian (Spike) Busch Gardens Tampa Bay in 2013, then
Smithsonian’s National Zoo in 2018
alive
F Asian (Kamala) Smithsonian’s National Zoo alive
F Asian (Swarna) Smithsonian’s National Zoo alive
F Asian (Maharani) Smithsonian’s National Zoo alive
Greenville Zoo (SC) 2014 F African (Joy) Cheyenne Mountain Park Zoo d. en route to zoo
(Continued)
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 25/41
sanctuaries offer a legitimate option for elephants in need of rescue or placement, as
evidenced by the number of elephants sent from North American zoos to these facilities.
Currently, the number of elephant sanctuaries is limited, with two accredited facilities in
the U.S. (Global Federation of Animal Sanctuaries, 2024) and few others around the world.
CONCLUSION
In conclusion, we have focused on research conducted at accredited zoos, where higher
levels of welfare are expected and indeed mandated. A review of the literature suggests that
accredited zoos today are more focused on welfare and make an effort to enrich the lives of
their elephants. Nevertheless, the evidence demonstrates that serious health and welfare
Table 1 (continued )
Zoological facility
1
Final year Elephant
2
Transfer to
3
Status
4
Woodland Park Zoo (WA) 2015 F Asian (Chai) Oklahoma City Zoo d. 2016
F Asian (Bamboo) Oklahoma City Zoo d. 2022
Lee Richardson Zoo (KS) 2015 F African (Missy) Cheyenne Mountain Park Zoo alive
F African (Kimba) Cheyenne Mountain Park Zoo alive
Nashville Zoo (TN) 2015 F African (Sukari) TES alive
F African (Hadari) TES d. 2017
F African (Rosie) TES d. 2016
Virginia Zoo (VA) 2016 F African (Cita) Zoo Miami d. 2019
F African (Lisa) Zoo Miami d. 2017
Buffalo Zoo (NY) 2018 F Asian (Surapa) Audubon Zoo alive
F Asian (Jothi) Audubon Zoo alive
Riverbanks Zoo (SC) 2019 F African (Belle) Milwaukee Zoo alive
Santa Barbara Zoo (CA) 2019 No surviving
elephants
San Antonio Zoo (TX) 2023 F Asian (Nichole) TES d. 2023
Hogle Zoo (UT) 2023 F African (Christie) Kansas City Zoo alive
F African (Zuri) Kansas City Zoo alive
Knoxville Zoo (TN) 2023 F African (Edie) TES alive
F African (Jana) TES d. 2023
El Paso Zoo (TX) 2024 No surviving
elephants
Oakland Zoo (CA) 2024
(announced
July 2024)
M African (Osh) TES alive
Point Defiance Zoo (WA) 2024 No surviving
elephants
Louisville Zoo (KY) 2025
(announced
March 2024)
F Asian (Punch) TES alive
F African (Mikki) TES alive
Notes:
1
Not included here are the Niabi Zoo (IL) and Six Flags Discovery Kingdom (CA), which lost/relinquished AZA accreditation prior to terminating their elephant
exhibits.
2
F, female; M, male.
3
TES, The Elephant Sanctuary in Tennessee; PAWS, Performing Animal Welfare Society (CA); TNEC, The National Elephant Center (FL).
4
d = year of death; alive as of 7/6/2024.
Doyle et al. (2024), PeerJ, DOI 10.7717/peerj.18161 26/41
challenges persist, suggesting that, for practical and ethical purposes, elephants are
generally unsuited to captive conditions. The declining number of AZA accredited zoos
housing elephants speaks to the many challenges of keeping them in captivity. As we move
forward with increased interest in the overall well-being of these and other animals, it will
be important to recognize when certain environments cannot provide what some species
need to flourish, and to consider science-informed policies determining which species
could continue to be bred and kept in zoos and other captive facilities, and which species
should not.
ADDITIONAL INFORMATION AND DECLARATIONS
Funding
The authors received no funding for this work.
Competing Interests
Catherine Doyle is the director of science, research, and public policy at the Performing
Animal Welfare Society (PAWS). Heather Rally is the founder of and veterinarian at
Thrive Wild. Lester O’Brien is the founder of Palladium Elephant Consulting Inc. Lori
Marino is an adjunct professor at New York University, and is president of the Whale
Sanctuary Project.
Author Contributions
.Catherine Doyle conceived and designed the research, analyzed the data, prepared
figures and/or tables, authored or reviewed drafts of the article, and approved the final
draft.
.Heather Rally performed the research, analyzed the data, authored or reviewed drafts of
the article, and approved the final draft.
.Lester O’Brien performed the research, analyzed the data, authored or reviewed drafts of
the article, and approved the final draft.
.Mackenzie Tennison analyzed the data, authored or reviewed drafts of the article, and
approved the final draft.
.Lori Marino conceived and designed the research, analyzed the data, authored or
reviewed drafts of the article, and approved the final draft.
.Bob Jacobs conceived and designed the research, analyzed the data, prepared figures and/
or tables, authored or reviewed drafts of the article, and approved the final draft.
Data Availability
The following information was supplied regarding data availability:
This is a literature review.
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