Calculation of longevity and life expectancy in captive elephants

Abstract

The concepts of longevity (longest lived) and life expectancy (typical age at death) are common demographic parameters that provide insight into a population. Defined as the longest lived individual, longevity is easily calculated but is not representative, as only one individual will live to this extreme. Longevity records for North American Asian elephants (Elephas maximus) and African elephants (Loxodonta africana) have not yet been set, as the oldest individuals (77 and 53 years, respectively) are still alive. One Asian elephant lived to 86 years in the Taipei Zoo. This is comparable to the maximum (though not typical) longevity estimated in wild populations. Calculation of life expectancy, however, must use statistics that are appropriate for the data available, the distribution of the data, and the species' biology. Using a simple arithmetic mean to describe the non‐normally distributed age at death for elephant populations underestimates life expectancy. Use of life‐table analysis to estimate median survivorship or survival analysis to estimate average survivorship are more appropriate for the species' biology and the data available, and provide more accurate estimates. Using a life‐table, the median life expectancy for female Asian elephants (Lx=0.50) is 35.9 years in North America and 41.9 years in Europe. Survival analysis estimates of average life expectancy for Asian elephants are 47.6 years in Europe and 44.8 years in North America. Survival analysis estimates for African elephants are less robust due to less data. Currently the African elephant average life expectancy estimate in North America is 33.0 years, but this is likely to increase with more data, as it has over the past 10 years. Zoo Biol 23:365–373, 2004. © 2004 Wiley‐Liss, Inc.

Zoo and aquarium research: priority setting for the coming decades

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“…In addition, ''experts'' on wild populations of elephants have categorically stated that zoos do not offer appropriate space for elephants. Owing to a glaring lack of information, zoos have been relegated to countering such accusations with ad hoc, largely qualitative citations of ''expertise,'' descriptions of their conservation roles and commitment to elephant welfare and care, and expressions of the need for further research [Smith and Hutchins, 2000;AZA 2001;Hutchins, 2006b]; they have thus far responded with only one rigorous scientific study [which showed that the average life span of zoo elephants was similar to that of free-ranging individuals; Wiese and Willis, 2004].…”

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Morpho/Proteomic Comparative between High Grade Pleomorphic Sarcoma and Metastasis Diagnosed in an Old Captive Common Hippo

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