Captive breeding and infant mortality in Asian elephants: A comparison between twenty western zoos and three eastern elephant centers

Poor reproductive success compromises the long-term viability of captive Asian elephant populations. A questionnaire was designed to assess the importance of reproductive behavior and husbandry factors on breeding success. This was circulated to a number of institutions, zoos, and circuses in Asia, Europe, and North America, all of which kept Asian elephants. The aims were to compare Asian elephant breeding success in different institutions, establish possible causes for any differences, and make recommendations for improving the welfare and breeding success of the animals. The results showed that breeding success in most of the zoos was notably lower and the percentages of stillbirths and infant mortality were relatively higher when compared with those of the institutions in Asia. Female elephants in zoos appeared to reach sexual maturity and reproduce earlier than those in the Asian establishments. However, zoo elephants produced fewer young per female. The different facilities and husbandry methods used are described. Recommendations are made for both short- and long-term changes that could be used to modify existing practices to improve the welfare and breeding success of captive Asian elephants. Zoo Biol 17:311–332, 1998. © 1998 Wiley-Liss, Inc.     

Calculation of longevity and life expectancy in captive elephants

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.     

Elephant Genomes Reveal Accelerated Evolution in Mechanisms Underlying Disease Defenses

Disease susceptibility and resistance are important factors for the conservation of endangered species, including elephants. We analyzed pathology data from 26 zoos and report that Asian elephants have increased neoplasia and malignancy prevalence compared with African bush elephants. This is consistent with observed higher susceptibility to tuberculosis and elephant endotheliotropic herpesvirus (EEHV) in Asian elephants. To investigate genetic mechanisms underlying disease resistance, including differential responses between species, among other elephant traits, we sequenced multiple elephant genomes. We report a draft assembly for an Asian elephant, and defined 862 and 1,017 conserved potential regulatory elements in Asian and African bush elephants, respectively. In the genomes of both elephant species, conserved elements were significantly enriched with genes differentially expressed between the species. In Asian elephants, these putative regulatory regions were involved in immunity pathways including tumor-necrosis factor, which plays an important role in EEHV response. Genomic sequences of African bush, forest, and Asian elephant genomes revealed extensive sequence conservation at TP53 retrogene loci across three species, which may be related to TP53 functionality in elephant cancer resistance. Positive selection scans revealed outlier genes related to additional elephant traits. Our study suggests that gene regulation plays an important role in the differential inflammatory response of Asian and African elephants, leading to increased infectious disease and cancer susceptibility in Asian elephants. These genomic discoveries can inform future functional and translational studies aimed at identifying effective treatment approaches for ill elephants, which may improve conservation.     

Survey of the reproductive cyclicity status of Asian and African elephants in North America

The Asian and African elephant populations in North America are not self‐sustaining, and reproductive rates remain low. One problem identified from routine progestagen analyses is that some elephant females do not exhibit normal ovarian cycles. To better understand the extent of this problem, the Elephant TAG/SSP conducted a survey to determine the reproductive status of the captive population based on hormone and ultrasound evaluations. The survey response rates for facilities with Asian and African elephants were 81% and 71%, respectively, for the studbook populations, and nearly 100% for the SSP facilities. Of the elephants surveyed, 49% of Asian and 62% of African elephant females were being monitored for ovarian cyclicity via serum or urinary progestagen analyses on a weekly basis. Of these, 14% of Asian and 29% of African elephants either were not cycling at all or exhibited irregular cycles. For both species, ovarian inactivity was more prevalent in the older age categories (>30 years); however, acyclicity was found in all age groups of African elephants. Fewer elephant females (～30%) had been examined by transrectal ultrasound to assess reproductive‐tract integrity, and corresponding hormonal data were available for about three‐quarters of these females. Within this subset, most (～75%) cycling females had normal reproductive‐tract morphologies, whereas at least 70% of noncycling females exhibited some type of ovarian or uterine pathology. In summary, the survey results suggest that ovarian inactivity is a significant reproductive problem for elephants held in zoos, especially African elephants. To increase the fecundity of captive elephants, females should be bred at a young age, before reproductive pathologies occur. However, a significant number of older Asian elephants are still not being reproductively monitored. More significantly, many prime reproductive‐age (10–30 years) African females are not being monitored. This lack of information makes it difficult to determine what factors affect the reproductive health of elephants, and to develop mitigating treatments to reinitiate reproductive cyclicity. Zoo Biol 23:309–321, 2004. © 2004 Wiley‐Liss, Inc.     

Skewed birth sex ratio and premature mortality in elephants

Sex allocation theories predict equal offspring number of both sexes unless differential investment is required or some competition exists. Left undisturbed, elephants reproduce well and in approximately even numbers in the wild. We report an excess of males are born and substantial juvenile mortality occurs, perinatally, in captivity. Studbook data on captive births (CB, n = 487) and premature deaths (PD, <5 years of age; n = 164) in Asian and African elephants in Europe and North America were compared with data on Myanmar timber (Asian) elephants (CB, n = 3070; PD, n = 738). Growth in CB was found in three of the captive populations. A significant excess of male births occurred in European Asian elephants (ratio: 0.61, P = 0.044) and in births following artificial insemination (0.83, P = 0.003), and a numerical inclination in North American African elephants (0.6). While juvenile mortality in European African and Myanmar populations was 21–23%, it was almost double (40–45%) in all other captive populations. In zoo populations, 68–91% of PD were within 1 month of birth with stillbirth and infanticide being major causes. In Myanmar, 62% of juvenile deaths were at >6 months with maternal insufficient milk production, natural hazards and accidents being the main causes. European Asian and Myanmar elephants PD was biased towards males (0.71, P = 0.024 and 0.56, P < 0.001, respectively). The skewed birth sex ratio and high juvenile mortality hinder efforts to help captive populations become self-sustaining. Efforts should be invested to identify the mechanism behind these trends and seek solutions for them.     

Public Attitudes in India and Australia toward Elephants in Zoos

ABSTRACT

We surveyed the attitudes of people toward captive elephants in australia, where importation into zoos has been controversial recently, compared with India, where elephants are indigenous. Both australian (AR, n = 101) and Indian (IR, n = 101) respondents rated conservation as the most important reason for the role of zoos and sanctuaries. Australian respondents were more concerned about the husbandry conditions for keeping wild animals in zoos and sanctuaries than Indian respondents (p = 0.02). This concern for captive animals increased with the higher educational level of the respondents. Female australian respondents were more concerned about the practice of keeping elephants in captivity than australian men. More australian respondents were prepared to pay extra to visit a zoo with elephants (AR 42.6%, IR 7.9%, p < 0.001). Indian respondents believed more than their australian counterparts that it was important for any zoo to display elephants, and wanted to interact with elephants by feeding, touching, and riding on them. While australian respondents? perceptions of captive elephants acknowledged their scientific value, Indian respondents viewed elephants primarily of religious, cultural, and historical significance. We conclude that australians and Indians have different requirements for keeping elephants in zoos, which should inform zoo directors about the best way to present them to the public.     

Why inter‐country loans will not help sumatra's elephants

Asian elephants (Elephas maximus) in western zoos are likely to become extinct unless elephants are regrouped into breeding units or additional elephants are imported from range States. There have been proposals for the export of elephants from elephant camps in Sumatra, Indonesia. In exchange, zoos would be expected to provide funds or support ‘in kind’ for the camps or for the conservation of wild elephants. Most of the elephants in the Sumatran camps were captured because of crop‐raiding problems around protected areas or because elephant habitat has been and continues to be lost to development schemes and illegal conversion of protected areas to agriculture. Capture‐related mortality rates are high and conditions in the camps are poor, with low standards of veterinary care and husbandry. This is partly due to over‐crowding and inadequate budgets. It might seem, therefore, that the loan of elephants to western zoos would improve the lot of these elephants and reduce the pressures on the camps. However, we show that both total and annual demand for Asian elephants, and particularly Sumatran elephants (E. m. sumatranus), by western zoos are low, and consequently the resources generated by any loan scheme would be limited. Elephant loan schemes are unlikely to have significant beneficial impact on either the conservation or welfare of elephants in Sumatra. More importantly, a credible loan scheme would require a permanent moratorium on the capture of wild elephants in Sumatra. Such a moratorium is needed to prevent illicit captures for sale or loan. At present, wild elephants are caught to replace those that die at the camps or are moved to other facilities. Without a moratorium, the loan of elephants to overseas zoos would contribute directly to reductions in wild elephant populations in Sumatra. However, a moratorium is likely to prove impossible to enforce, and this alone should call into question the desirability of any loan scheme. Zoo Biol 25:235–246, 2006. © 2006 Wiley‐Liss, Inc.     

Results of the third reproductive assessment survey of North American Asian (Elephas maximus) and African (Loxodonta africana) female elephants

A written survey assessed reproductive status of female Asian and African elephants in AZA/SSP facilities in 2008, and data were compared to surveys conducted in 2002 and 2005. Results showed that ovarian acyclicity rates across the surveys remained unchanged for Asian (13.3, 10.9 and 11.1%) and African (22.1, 31.2 and 30.5%) elephants, respectively (P > 0.05), but were higher overall for African compared to Asian elephants (P < 0.05). In 2008, the percentages of Asian and African elephants with irregular cycles (14.3 and 15.8%) and irregular + no cycles (25.4 and 46.4%) was similar to 2005 (7.6 and 11.8%; 18.5 and 43.0%), but were increased compared to 2002 (2.6 and 5.2%; 16.0 and 27.3%), respectively (P < 0.05). For both species, ovarian acyclicity increased with age (P < 0.05). Reproductive tract pathologies did not account for the majority of acyclicity, although rates were higher in noncycling females (P < 0.05). Bull presence was associated with increased cyclicity rates (P < 0.05) for Asian (92.5 vs. 58.3%) and African (64.9 vs. 57.8%) elephants compared to females at facilities with no male, respectively. Cyclicity rates were higher for Asian (86.8 vs. 65.2%) and African (67.9 vs. 56.7%) elephants managed in free compared to protected contact programs (P < 0.05), respectively. Geographical facility location had no effect on cyclicity (P > 0.05). In summary, incidence of ovarian cycle problems continues to predominantly affect African elephants. Although percentages of acyclicity did not increase between 2005 and 2008, 42.2% Asian and 30.2% African females were no longer being hormonally monitored; thus, reproductive cycle abnormalities could be worse than current data suggest.     

CYTOGENETIC STUDIES IN THE DRYOPTERIS SPINULOSA COMPLEX. II.

Walker , S. (Liverpool U., England.) Cytogenetic studies in the Dryopteris spinulosa complex. II. Amer. Jour. Bot. 48(7): 607–614. Illus. 1961.—A comparison of the D. spinulosa complex, as represented in North America, is made with that in Europe. Although in North America, other Dryopteris species are known to hybridize with members of the complex, the report has been limited to species which compare directly with those in Europe. Three tetraploid species and 2 diploids, the latter representing at least 1 ancestral genome in the complex, are discussed together with the interspecific hybrids. Synthetic hybrids have been produced, involving taxa from both sides of the Atlantic. Evidence from these hybrids suggests that D. intermedia, of North America, and D. maderensis, of Madeira, are conspecific.     

The historical development of zoo elephant survivorship

In the discussion about zoo elephant husbandry, the report of Clubb et al. (2008, Science 322: 1649) that zoo elephants had a “compromised survivorship” compared to certain non-zoo populations is a grave argument, and was possibly one of the triggers of a large variety of investigations into zoo elephant welfare, and changes in zoo elephant management. A side observation of that report was that whereas survivorship in African elephants (Loxodonta africana) improved since 1960, this was not the case in Asian elephants (Elephas maximus). We used historical data (based on the Species360 database) to revisit this aspect, including recent developments since 2008. Assessing the North American and European populations from 1910 until today, there were significant improvements of adult (≥10 years) survivorship in both species. For the period from 1960 until today, survivorship improvement was significant for African elephants and close to a significant improvement in Asian elephants; Asian elephants generally had a higher survivorship than Africans. Juvenile (<10 years) survivorship did not change significantly since 1960 and was higher in African elephants, most likely due to the effect of elephant herpes virus on Asian elephants. Current zoo elephant survivorship is higher than some, and lower than some other non-zoo populations. We discuss that in our view, the shape of the survivorship curve, and its change over time, are more relevant than comparisons with specific populations. Zoo elephant survivorship should be monitored continuously, and the expectation of a continuous trend towards improvement should be met.     

Aimed Object-throwing by a Wild African Elephant in an Interspecific Encounter

A wild and presumably female African elephant (Loxodonta africana) was observed when she threw with her trunk various materials - mud, soil, vegetation - to an interfering white rhino (Ceratotherium simum). Objectthrowing, a special type of animal tool-behaviour, seems to be used by elephants not only in aggression but also for exploration     

The tables are turned: an invasive species under potential threat

This study reviews the current distribution of the native Asian common walking catfish (Clarias batrachus) within Singapore, and compares the present distribution to its historical distribution in the last 90 years based on literature records and museum material. We record a severe decline in the distribution of C. batrachus in Singapore concomitant with a sharp increase in the distribution of the invasive African sharptooth catfish (Clarias gariepinus). We review evidence suggesting that the introduction and the establishment of the African sharptooth catfish in Singapore have adversely affected the Asian common walking catfish. The potential displacement by the African sharptooth catfish of the Asian common walking catfish—itself a widespread invader in other parts of Asia and North America—is particularly interesting as an example of a notorious invasive species becoming threatened by an exotic within its own native range.     

Long‐term administration of α‐tocopherol in captive Asian elephants (Elephas maximus)

After the loss of an African elephant (Loxodonta africana) in February 1989 at the Denver Zoological Gardens (DZG) with very low circulating serum α‐tocopherol, a long‐term study was initiated with three Asian elephants (Elephas maximus) to evaluate the effect of an oral micellized, water‐soluble, natural source d‐α‐tocopherol supplement. Baseline α‐tocopherol levels were evaluated and found to be approximately 3.75‐fold less than those reported for semi‐free‐ranging Asian Nepalese work camp and free‐ranging African elephants. The DZG elephants were then administered a liquid d‐α‐tocopherol (Emcelle^®) at 2.2 IU/kg body weight orally once daily. Serum samples were obtained and analyzed at 1, 2, 8, and 12 months and then annually for 96 months. The oral vitamin E supplement significantly elevated serum levels above baseline and were found to be comparable with levels reported for semi–free‐ranging and free‐ranging elephants. Zoo Biol 20:245–250, 2001. © 2001 Wiley‐Liss, Inc.     

Examination of the interrelationships of behavior,dominance status,and ovarian activity in captive Asian and African elephants

Ovarian inactivity has been identified in captive African (Loxodonta africana) and Asian (Elephas maximus) elephants and is thought to be mediated in part by social influences. Thus, a survey was conducted to determine how behavior and dominance status relate to each other and to ovarian cyclicity. For both Asian and African elephants, dominance status was positively correlated with relative size, age, temperament, disciplinary nature, and willingness to share novel objects. Relative size and temperament were also related to disciplinary nature toward herdmates. Behavior toward keepers was a good indicator of the willingness of elephants to follow commands, whereas sharing novel objects was positively correlated with object curiosity. Finally, dominance status, temperament, and disciplinary nature were all correlated with willingness to share. Comparisons of ovarian cyclicity status with behavior rankings were conducted only for African elephants because of the low number of noncycling Asian elephants surveyed. Overall, social status appeared to be the best predictor of ovarian activity in African elephants. Noncycling African elephant females ranked higher in the dominance hierarchy and gave more discipline to herdmates than cycling cohorts. It remains to be determined whether these are cause or effect relationships, but clearly it is important to understand how physical and social attributes impact physiological processes, such as reproduction. Captive management now needs to focus on optimizing social and environmental conditions to maximize reproductive potential in elephants. Zoo Biol 23:431–448, 2004. © 2004 Wiley‐Liss, Inc.     

Generation and Characterization of Antibodies against Asian Elephant (Elephas maximus) IgG,IgM, and IgA

Asian elephant (Elephas maximus) immunity is poorly characterized and understood. This gap in knowledge is particularly concerning as Asian elephants are an endangered species threatened by a newly discovered herpesvirus known as elephant endotheliotropic herpesvirus (EEHV), which is the leading cause of death for captive Asian elephants born after 1980 in North America. While reliable diagnostic assays have been developed to detect EEHV DNA, serological assays to evaluate elephant anti-EEHV antibody responses are lacking and will be needed for surveillance and epidemiological studies and also for evaluating potential treatments or vaccines against lethal EEHV infection. Previous studies have shown that Asian elephants produce IgG in serum, but they failed to detect IgM and IgA, further hampering development of informative serological assays for this species. To begin to address this issue, we determined the constant region genomic sequence of Asian elephant IgM and obtained some limited protein sequence information for putative serum IgA. The information was used to generate or identify specific commercial antisera reactive against IgM and IgA isotypes. In addition, we generated a monoclonal antibody against Asian elephant IgG. These three reagents were used to demonstrate that all three immunoglobulin isotypes are found in Asian elephant serum and milk and to detect antibody responses following tetanus toxoid booster vaccination or antibodies against a putative EEHV structural protein. The results indicate that these new reagents will be useful for developing sensitive and specific assays to detect and characterize elephant antibody responses for any pathogen or vaccine, including EEHV.     

Secretory patterns of serum prolactin in Asian (Elephas maximus) and African (Loxodonta africana) elephants during different reproductive states: Comparison with concentrations in a noncycling African elephant

Serum prolactin was quantified in adult female Asian (Elephas maximus) and African (Loxodonta africana) elephants during various reproductive states and the profiles compared to that in a noncycling African elephant. In reproductively normal elephants, there was no effect of season, estrous cycle stage, or lactational status on quantitative or qualitative prolactin secretion (P > 0.05), nor where there any differences (P > 0.05) in overall prolactin concentrations between species. In pregnant elephants, prolactin concentrations remained at baseline for the first 4–6 months of gestation. Thereafter, concentrations during early pregnancy averaged ∼four-fold higher than those during the estrous cycle, increasing to ∼100-fold over baseline during mid- to late gestation in both species. In contrast to cycling elephants, prolactin concentrations in an African elephant exhibiting chronic anovulation (on the basis of an acyclic serum progesterone profile) and mild galactorrhea were consistently about five-fold higher (P < 0.05), suggesting she is hyperprolactinemic. Other endocrinological assesments confirmed the hypogonadal state of this female. Serum estradiol concentrations were consistently at or below detectable levels. Additionally, no preovulatory luteinizing hormone (LH) surges occurred in daily serum samples analyzed over a 12-month period. The pituitary was not totally refractory, however, and responded with a several-fold increase in serum LH concentration (peak, 3.07 ng/ml) over baseline (0.75 ng/ml) after i.v. injection of gonadotropin-releasing hormone. This study describes normal baseline serum prolactin values for Asian and African elephants and is the first to identify hyperprolactinemia as a possible cause of reproductive acyclicity and galactorrhea in an African elephant. Zoo Biol 16:149–159, 1997. © 1997 Wiley-Liss, Inc.     

From left to right all through the night: Characteristics of lying rest in zoo elephants

Despite increased research during the past years, many characteristics of resting behavior in elephants are still unknown. For example, there is only limited data suggesting elephants express longer lying bouts and increased total nightly lying durations on soft substrates as compared to hard surfaces. Additionally, it has not been investigated how frequently elephants change body sides between lying bouts. Here we present these characteristics based on observations of nighttime lying behavior in 10 zoo elephants (5 African Loxodonta africana and 5 Asian Elephas maximus elephants) living in five different European facilities. We found that elephants housed on soft substrates have significantly increased total lying durations per night and longer average lying bouts. Furthermore, at 70%−85% of all bouts, a consistently higher frequency of side change between lying bouts occurred on soft substrates, leading to an overall equal laterality in resting behavior. Deviations from this pattern became evident in elephants living on nonsand flooring or/and in nondominant individuals of nonfamily groups, respectively. Based on our findings, we consider elephants to normally have several lying bouts per night with frequent side changes, given an appropriate substrate and healthy social environment. We encourage elephant-keeping facilities to monitor these characteristics in their elephants' nighttime behavior to determine opportunities for further improvements and detect alterations putatively indicating social or health problems in individual elephants at an early stage.     

Historical range and movements of the Elephants in Babile Elephant Sanctuary,Ethiopia

A study on historical range and movement patterns of the African savannah elephants (Loxodonta africana africana) in Ethiopia was made from December 2004 to November 2008. Babile Elephant Sanctuary is one of the strongholds of elephants in the country, where it now supports approximately 27% of the elephant population in Ethiopia. Elephant movement routes and ranges were identified based on interviews of local people and by tracking the animals in the field. Elephants of the Sanctuary were categorized into two distinctive groups or clans based on their movement patterns and their associations to each other. Three major valleys, namely Gobele, Erer and Dakata, were crossed by elephants. Elephants in the population had an estimated annual range of 3014 km². Of this, 85.7% (2583 km²) was inside the Sanctuary and 14.3% (430 km²) outside but adjacent to the Sanctuary. Elephant use outside of the Sanctuary included three different areas: Upper Erer Valley (8 km²), Upper Gobele Valley (48 km²) and west of Gobele Valley (374 km²). The extent of range varied seasonally. During the wet season, elephant range was restricted to Erer Valley and its tributaries (1266 km² and a density of approximately 0.25 animal km^?2), or 42% smaller than the dry season range (1417 km², 0.23 elephant km^?2). Range use was smallest (332 km²) in October to November and from April to May. During the dry season, elephants were found in two distinctive groups, one using Gobele Valley and the other Erer Valley.     

Feasibility of characterizing reproductive events in large nondomestic species by transrectal ultrasonic imaging

The feasibility of using transrectal ultrasonography for imaging the in situ morphology of the reproductive tract of females of several large nondomestic and endangered species was studied. Two black (Diceros bicornis) and 1 white (Diceros simus) rhinoceros, 2 Asian (Elaphus maximus) and 2 African (Loxodonta africana) elephants, 4 banteng (Bos javanicus), 1 gaur (Bos taurus), 1 giraffe (Giraffa camelopardalis), and 1 bactrian camel (Camelus bactrianus) were examined. Real-time ultrasonic images were obtained for the following structures: 1) rhinoceros—corpus luteum, ovarian follicles, uterus, cervix, and early conceptus, 2) elephants—posterior uterus and cervix, 3) banteng and gaur—corpus luteum, ovarian follicles, uterus, cervix, and conceptus, 4) giraffe—posterior uterus, placentomes, and late conceptus, 5) camel—posterior uterus, fetal fluids, and fetal membranes. Individual ovarian follicles were identified and monitored over a 34 day observational period in 1 nontranquilized white rhinoceros. Difficulties and limitations in viewing the ovaries in the elephants were attributed to operator inexperience and to the size, positioning, and demeanor of the animals. Pregnancy was detected in 1 black rhinoceros (27 days), 1 banteng cow (48 days), the giraffe (13 months), and in the bactrian camel (approximately 3½ months). Impending embryonic loss was suspected in the banteng cow because a heartbeat was not detected in the embryo proper; the cow was subsequently diagnosed nonpregnant by transrectal palpation 20 days later. It is concluded that the ability afforded by transrectal ultrasonography to detect and measure ovarian structures and changes in morphology of the tubular genitalia and conceptus provides a research methodology for the elucidation of certain aspects of reproductive biology, and a clinical modality for reproductive management and assisted fertilization programs of large nondomestic species.     

Salient features in the locomotion of proboscideans revealed via the differential scaling of limb long bones

The standard differential scaling of proportions in limb long bones (length against circumference) was applied to a phylogenetically wide sample of the Proboscidea, Elephantidae and the Asian (Elephas maximus) and African (Loxodonta africana) elephants. In order to investigate allometric patterns in proboscideans and terrestrial mammals with parasagittal limb kinematics, the computed slopes between long bone lengths and circumferences (slenderness exponents) were compared with published values for mammals, and studied within a framework of the theoretical models of long bone scaling under gravity and muscle forces. Limb bone allometry in E. maximus and the Elephantidae is congruent with adaptation to bending and/or torsion induced by muscular forces during fast locomotion, as in other mammals, whereas the limb bones in L. africana appear to be adapted for coping with the compressive forces of gravity. Hindlimb bones are therefore more compliant than forelimb bones, and the resultant limb compliance gradient in extinct and extant elephants, contrasting in sign to that of other mammals, is shown to be a new important locomotory constraint preventing elephants from achieving a full‐body aerial phase during fast locomotion. Moreover, the limb bone pattern of African elephants, indicating a noncritical bone stress not increasing with increments in body weight, explains why their mean and maximal body masses are usually above those for Asian elephants. Differences in ecology may be responsible for the subtle differences observed in vivo between African and Asian elephants, but they appear to be more pronounced when revealed via mechanical patterns dictated by limb bone allometry. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 16–29.