The historical development of zoo elephant survivorship

“The assumed maximum longevity was based on the AnAge database (de Magalhães & Costa, 2009).”

“…(Gough & Kerley, 2006), Tarangire National Park (Foley & Faust, 2010), Karibu Amboseli National Park (excluding human ‐ caused mortality from Moss, 2001; total mortality from Clubb et al., 2008), Samburu and National Springs National Reserves (Wittemyer et al., 2013) and of Asian elephants…”

“Survivorship curves for large precocial mammals with reduced exposure to predation should have a convex or “ Type I ” shape (Pearl, 1927), irrespective of whether historical populations achieve this shape or not.”

“…human care aims at protecting from biotic and abiotic causes of mortality, survivorship would be expected to be generally higher, or its inverse — the rate of ageing — would be expected to be lower in zoos compared to natural habitats (Lemaître et al., 2013; Ricklefs, 2010; Tidière et al., 2016).”

“For the most recent time period of the discrete categories (2010 – 2019), the analysis did not yield a reliable result, due to the small sample size (yet results were identical when running the analysis without this cohort).”

“…National Park (Foley & Faust, 2010), Karibu Amboseli National Park (excluding human ‐ caused mortality from Moss, 2001; total mortality from Clubb et al., 2008), Samburu and National Springs National Reserves (Wittemyer et al., 2013) and of Asian elephants for Myanmar Timber elephants…”

“To generate these benchmarks, survival data in the in situ populations was corrected for human ‐ induced mortality in wild African elephants, and for the consequence of “ breaking in ” Asian timber elephants (Clubb et al., 2008; Mason & Veasey, 2010b).”

“For visual comparison only, survival curves for individuals ≥ 10 years of age were taken from the literature (Clubb et al., 2008; Foley & Faust, 2010; Gough & Kerley, 2006; Mar, 2007; Moss, 2001; Sukumar, 1992; Wittemyer et al., 2013).”

“For visual comparison only, survival curves for individuals ≥ 10 years of age were taken from the literature (Clubb et al., 2008; Foley & Faust, 2010; Gough & Kerley, 2006; Mar, 2007; Moss, 2001; Sukumar, 1992; Wittemyer et al., 2013).”

“For visual comparison only, survival curves for individuals ≥ 10 years of age were taken from the literature (Clubb et al., 2008; Foley & Faust, 2010; Gough & Kerley, 2006; Mar, 2007; Moss, 2001; Sukumar, 1992; Wittemyer et al., 2013).”

“For female African elephants, a higher sensitivity for ovarian cycle problems than in Asian elephants was detected (Brown et al., 2016; Oerke et al., 2002), pointing toward a generally more sensitive nature of this species.”

“…intensified (Mason & Veasey, 2010a), leading to one of the most comprehensive, concerted investigations of welfare for nondomestic species (Carlstead et al., 2013) with results documented in a special issue of a scientific journal (Meehan et al., 2016), and many more studies than can be cited here.”

“…human care aims at protecting from biotic and abiotic causes of mortality, survivorship would be expected to be generally higher, or its inverse — the rate of ageing — would be expected to be lower in zoos compared to natural habitats (Lemaître et al., 2013; Ricklefs, 2010; Tidière et al., 2016).”

“A seeming increase in newborn mortality in 1990 − 2009 may also be related to a higher proportion of primiparous births at this time (Stevenson, 2004), an effect also reported in the Myanmar timber elephant population (Mar et al., 2012).”

“…life expectancy while including animals subject to historical husbandry conditions might not reflect current husbandry practices; (ii) calculating an average age at death for all animals that have died does not account for the potential lifespans of those animals still alive (Wiese & Willis, 2004).”

“” The judgment of “ compromised ” was made when comparing zoo elephant survival against “ two well ‐ documented in situ populations judged to yield demographic benchmarks that zoos should reasonably meet or exceed ” (Clubb et al., 2009).”

“…welfare intensified (Mason & Veasey, 2010a), leading to one of the most comprehensive, concerted investigations of welfare for nondomestic species (Carlstead et al., 2013) with results documented in a special issue of a scientific journal (Meehan et al., 2016), and many more studies than can be…”

“Mason & Veasey, (2010b), reviewing the work of Saragusty et al. (2009), suggested some numerical improvement in first ‐ year mortality for both elephant species in Europe.”

“Hutchins (2006) already explained that the question of whether a certain population should be maintained or not is an ethical (and hence, a political) but not a scientific one, and that the variation of conditions observed in nature precludes unambiguous comparisons with other conditions.”

“In recent years, this most likely also reflects the impact of elephant herpes virus, an endemic infectious disease that represents the most common cause of death in juvenile Asian elephants in Western zoos (Fuery et al., 2020; Hoornweg et al., 2021; Perrin et al., 2021).”

“Obesity has been considered a problem in elephant husbandry and reproduction (Clubb et al., 2009; Hatt & Clauss, 2006), yet there is indication that body condition scores — at least in the European populations — have tended to decrease since 2000 (Schiffmann et al., 2019).”

“…questioned, because it is based on the assumption that juvenile and adult survivorship are so unrelated as to justify using these data from different populations, yet we know that density ‐ dependent effects occur in free ‐ ranging elephant populations (Hanks & McIntosh, 1973; Laws et al., 1975).”

“The average first ‐ year mortality of 21% for African elephants reported by Saragusty et al., (2009) (1962 − 2006) is of a similar magnitude as the 26% of our data set.”

“The awareness of the relevance of social structures of elephant herds led to a different approach to group composition and kin separation (Finch et al., 2021; Schmid et al., 2001; Schmidt & Kappelhof, 2019).”

“…documented, including orangutans ( Pongo sp.) (Wich et al., 2009), orcas ( Orcinus orca ) (Jett & Ventre, 2015), bottlenose dolphins ( Tursiops truncatus ) (Jaakkola & Willis, 2019) or chimpanzees ( Pan troglodytes ) (Havercamp et al., 2019), and many members of the Carnivora (Roller et al., 2021).”

“For Asian elephants, first ‐ year mortalities reported in the literature (1960 − 2006) are of a magnitude of 40% (Faust et al., 2006; Saragusty et al., 2009), which is higher than our recent finding of 22%.”

“…a historical improvement of zoo survivorship has been documented, including orangutans ( Pongo sp.) (Wich et al., 2009), orcas ( Orcinus orca ) (Jett & Ventre, 2015), bottlenose dolphins ( Tursiops truncatus ) (Jaakkola & Willis, 2019) or chimpanzees ( Pan troglodytes ) (Havercamp et al.,…”

“In recent years, this most likely also reflects the impact of elephant herpes virus, an endemic infectious disease that represents the most common cause of death in juvenile Asian elephants in Western zoos (Fuery et al., 2020; Hoornweg et al., 2021; Perrin et al., 2021).”

“…paying more attention to keeping adult animals, and especially breeding females, in an adequate body condition (Schiffmann et al., 2019; Sullivan et al., 2016) should also address the high birth weights and associated risk of stillbirths observed in zoo elephants (Dale, 2010; Kurt & Mar, 1996).”

“For different nondomestic species, a historical improvement of zoo survivorship has been documented, including orangutans ( Pongo sp.) (Wich et al., 2009), orcas ( Orcinus orca ) (Jett & Ventre, 2015), bottlenose dolphins ( Tursiops truncatus ) (Jaakkola & Willis, 2019) or chimpanzees ( Pan…”

“…documented, including orangutans ( Pongo sp.) (Wich et al., 2009), orcas ( Orcinus orca ) (Jett & Ventre, 2015), bottlenose dolphins ( Tursiops truncatus ) (Jaakkola & Willis, 2019) or chimpanzees ( Pan troglodytes ) (Havercamp et al., 2019), and many members of the Carnivora (Roller et al., 2021).”

“For female African elephants, a higher sensitivity for ovarian cycle problems than in Asian elephants was detected (Brown et al., 2016; Oerke et al., 2002), pointing toward a generally more sensitive nature of this species.”

“If viewed on its own, and compared to other zoo animals where sometimes distinct changes across decades can be observed (Roller et al., 2021), juvenile mortality might be considered stable in zoo elephants.”

“Intensive building activity led to new elephant enclosures around the world that not only provide more absolute space per animal but also more structure and animal ‐ environment interaction potential (Finch et al., 2021; Glaeser et al., 2021).”

“The awareness of the relevance of social structures of elephant herds led to a different approach to group composition and kin separation (Finch et al., 2021; Schmid et al., 2001; Schmidt & Kappelhof, 2019).”

“The awareness of the relevance of social structures of elephant herds led to a different approach to group composition and kin separation (Finch et al., 2021; Schmid et al., 2001; Schmidt & Kappelhof, 2019).”

“For example, Wendler et al. (2020) showed that foot health in European Asian zoo elephants was not related to a single factor but to a series of factors corresponding to modern husbandry.”

“…paying more attention to keeping adult animals, and especially breeding females, in an adequate body condition (Schiffmann et al., 2019; Sullivan et al., 2016) should also address the high birth weights and associated risk of stillbirths observed in zoo elephants (Dale, 2010; Kurt &…”

“Additionally, paying more attention to keeping adult animals, and especially breeding females, in an adequate body condition (Schiffmann et al., 2019; Sullivan et al., 2016) should also address the high birth weights and associated risk of stillbirths observed in zoo elephants (Dale, 2010; Kurt &…”

“However, there is now decreased reliance on wild importations, with populations relying almost entirely on ex-situ breeding efforts (Wiese and Willis, 2006; Clubb et al., 2009; Scherer et al., 2022).”

“With elephants, ZIMS has been used to evaluate female social contexts (87), survivorship (88), and hormone cycle patterns (37).”

“At least in captivity, Asian elephants appear to reach older ages than African savanna elephants (42).”

“…pyramid ’ is very helpful for understanding the sex and age distribution of a population, as this visual representation offers an easy and brief assessment, and also communication, of the breeding potential, the population growth, the population history, and potential present and future challenges.”

“Unlike previous analyses 6,8 , we did not split the data based on whether human-caused deaths were excluded to approximate “natural” mortality, as most populations in the wild now face considerable anthropogenic threats due to human activities and excluding such deaths would therefore not produce…”