Reproduction capacity of the Asian elephant in Europe
By Jeanette Schmid
Since 1976 the Asian elephant has been listed on Appendix I of CITES. In the last half of this century the wild population has declined to an estimated 34,000–54,000 individuals (Santiapillai and Jackson, 1990). The main reasons for this reduction are the increase of human population and human demands on natural resources, which destroy the living conditions of the elephants (Daniel, 1996).
The bad situation in the wild has affected the keeping of elephants in European zoos, where these animals have been kept since the 19th century. As a consequence of its listing as an endangered species, the captive population of Asian elephants in Europe is now managed by a European Endangered Species Programme (EEP). The aim of this programme is to build up a self-sustaining captive population of Asian elephants in European zoos, in the hope of bringing some animals back to the wild, as soon as the situation in their natural habitat has changed (Tudge, 1991). Successful breeding with avoidance of inbreeding, the production of behaviourally and ecologically competent animals (Ganslosser, 1995), and the cooperation of all elephant owners are preconditions of achieving these aims.
The present paper will give an overview of the size and composition of the captive population of Asian elephants in European zoos and circuses, their breeding success since 1902, and the problems which are involved in the captive breeding of this species. The basic data for the paper were collected by the European Elephant Group (Haufellner et al., 1993; European Elephant Group, 1996).
Captive population of Asian elephants in Europe
At present nearly 500 Asian elephants are kept in European zoos and circuses. In 1992 the exact number was 503 animals, of whom 204 (3.201) were in circuses. The whole population was distributed over 110 zoos and 51 circuses. Only 49 of the elephants were males (Haufellner et al., 1993), so the male-female ratio was 1:9. Both zoos and circuses prefer to keep females. The keeping of bulls is believed to be dangerous, because of the periodic musth phases during which the handling of bulls is nearly impossible, because they show increased aggression and irritability, and decreased responsiveness to the commands of their keepers (Jainudeen et al., 1972; Scheurmann and Jainudeen, 1972; Adams, 1981). The increase in aggression corresponds to increased testosterone serum levels during the musth phase (Rasmussen et al., 1984; Cooper et al., 1990; Niemüller and Liptrap, 1991) or up to two months before it (Lincoln and Ratnasooriya, 1996). A lot of accidents with musth bulls occurred in zoos and circuses in the past (Benirschke and Roocroft, 1992). In most cases the bull killed the keeper. Fear of accidents and the negative publicity following such events is one of the reasons why so many zoos and circuses do not keep bulls. Secure keeping of bulls is only possible if the zoo is able to build enclosures where direct contact between bull and keeper is not necessary during the musth phases (Kock, 1992). The financial means and the necessary space are not available in most zoos. A third reason why there are so few bulls in European zoos and circuses is that until 1976 it was not thought necessary to breed elephants, because it was no problem to import them from the countries of origin.
Figure 1. Age distribution of Asian elephants in European zoos and circuses in 1992. The population consists of 454 females (left side) and 49 males (right side) living in 110 zoos and 51 circuses. The ages of one male and 14 females are unknown.
Figure 1 represents the age distribution of the captive population of Asian elephants in Europe; 60% (274) of the females and 41% (19) of the males are between 21 and 30 years old. The accumulation in this age-group represents the last animals which were imported before the Asian elephant was listed on Appendix I of CITES 20 years ago. After this date the import of elephants was strictly limited. Thus only 95 females and 20 males in European zoos and circuses are younger than 20 years, and the age classes after 30 years include only a few animals of both sexes. In comparison with captive working elephants in Burma (Schmidt and Khyne U Mar, 1996), the life expectancy of captive elephants in European zoos and circuses is much lower (Figure 2). In Burma nearly 10% of the elephants reach an age near 60 years. In Europe only 1% of the animals is older than 50 years, and no animal has reached the age of 60. The reasons for this low life expectancy in Europe are not yet clear. The main causes of mortality in adult elephants are foot problems (Rüedi, 1990), difficulties during the change of molars (Kurt, 1995), attrition of the joints (Lindau, 1970; Adams, 1981) or elephant pox (Kuntze and Janetzky, 1982; Pade et al., 1990). The mean life expectancy of captive-born elephants in Europe, calculated from 81 elephants with known dates of death, is 6.1 years. Working elephants in Burma, on the other hand, reach mean life expectancies of nearly 30 years (Schmidt and Khyne U Mar, 1996). The very low level in European elephants results from a very high mortality rate in the first five years after birth.
Figure 2. Survival curve of captive Asian elephants in Europe and Burma. Each curve is calculated from 81 elephants with known dates of birth and death in European zoos (Haufellner et al., 1993) or in working camps in Burma (Schmidt and Khyne U Mar, 1996).
Births in Europe from 1902 to August 1996
Between 1902 and August 1996 there were 141 (52.81.8) births in European zoos and circuses (Haufellner et al., 1993; European Elephant Group, 1996). The male-female ratio is 1:1.6. Captive-born elephants in south India show a male-female ratio of 1:1 (Sukumar, 1989), similar to captive-born elephants in Burma (Schmidt and Khyne U Mar, 1996).
In Figure 3 the number of births for each decade in this century is shown. Births increased after the decade 1971–1980. This is a result of the efforts in zoos and circuses to breed these animals following the limitation of imports after 1976. In the present decade up to August 1996
Figure 3. Births in Europe (1902–August 1996). Number of births (y-axis) for each decade in the period from 1902 to August 1996 (x-axis). In the whole period 141 births took place (Haufellner et al., 1993; European Elephant Group, 1996).
Figure 4. Breeding bulls in Europe (1902–August 1996). For each decade (x-axis) in the period between 1902 and August 1996, the numbers of bulls (y-axis) who were active in breeding is shown. These are bulls who were responsible for at least one birth in this particular decade (Haufellner et al., 1993; European Elephant Group, 1996).
we have reached the highest birth level of the whole century. The increased breeding efforts in zoos become obvious from the number of bulls who are responsible for the births in each decade (Figure 4). In the last third of the century the number of breeding bulls has increased noticeably, indicating that more zoos have decided to keep bulls and made some efforts to breed. So breeding seems to have become more and more successful during the century, with regard to the number of births. But of the 141 calves born, 37% died within their first year. Figure 5 shows the development of the death rate over the decades of this century. There is no obvious trend towards improvement. In the last full decade, from 1981 to 1990, the death rate of calves in the first year was 50%. Sukumar (1989) analysed the death rate in a wild population in south India and calculated that it was 4–5% for females of 0–5 years and 8–9% for males in the same age class. The death rate in the first five years of working elephants in Burma is 8.1% (Schmidt and Khyne U Mar, 1996). The difference in first-year mortality rates between Europe and Burma is also the reason for the more gradual decline in the survival curve of the working elephants in Burma compared to the European population as shown in Fig. 2. Forty-eight per cent of the deaths in the first year in Europe are stillborn calves, 27% were killed by their mothers and 25% died from other causes. The high rate of stillborn calves could result from the greater weights of female elephants in European zoos and circuses compared to both captive and wild elephants in Asia (Kurt and Pucher, 1996). An investigation by Kurt and Khyne U Mar (1996) shows that stillbirths in Europe correlate with the weights of the mothers. Heavier mothers show a tendency to produce more stillborn calves. Likewise females in Europe produce calves after longer gestation periods (on average, 644.4 days) with larger neonate weights (105.6 kg) than working elephants in Asia (598.1 days, 74 kg) (Kurt and Khyne U Mar, 1996).
Figure 5. Death rate in the first year after birth (1902–August 1996). The figure shows the percentage of deaths (y-axis) in the first year after birth in each decade of the period between 1902 and 1996 (x-axis) (Haufellner et al., 1993; European Elephant Group, 1996). The mean value over all decades amounts to 37%.
Killing of babies by the mother is not described for captive elephants in Asia. The reasons for the high rate of this behaviour in Europe can only be discussed speculatively. The structure of the elephant groups in European zoos differs from the family groups in the wild, which consist of related adult females and their offspring. In zoos unrelated females, often from different regions of Asia, are kept together. In most cases all the animals are of about the same age. The elephants were separated from their mothers very early in life, mostly between one and two years, transported to Europe and kept together with other babies, or at least without an older female. In most cases the females have never seen a new-born elephant calf before they give birth to their own. The learning situation for development of species-typical social behaviour in zoos differs from that in the wild, where mothers, sisters and aunts guide the young elephant for years. Copulations and births are normal events in the life of a wild young elephant. The missing support of adult conspecifics during the first years might cause a reduced or disturbed development of social behaviour in zoo elephants, and this might result in killing new-born babies by their mothers.
Another reason for the killing of babies by their mothers may be human intervention during elephant births in European zoos and circuses. Elephants are among the zoo animals with the highest public interest (Pretzlaff et al., 1996). So the pregnancy and birth of elephants are good public relations events. On the other hand, a stillborn calf or a calf who is killed by the mother generates bad publicity, so zoo staff try everything to prevent such occurrences. Often they shackle a female giving birth on all four feet to save the baby from the kicks of the mother. In most cases there is veterinary intervention during birth (injection of oxytocin) and afterwards (injection of sedative). Sometimes journalists and TV are present during the birth to produce pictures of the rare event. In the wild pregnant females are accompanied by members of their group. Related females support them during labour and help the new-born babies to get up (Kurt, 1986). Zoo elephants do not have the support of their conspecifics. Birth is accompanied by a lot of unusual disturbances, which might cause the killing of the baby.
Breeding potential in captive European elephants
Sixty-one females and 45 males were responsible for the 141 births in Europe in this century. In the population of 1992 only 33 females and 16 males were or had been active in breeding – i.e. females who had given birth to at least one baby or were pregnant, and males who had been the father of at least one baby or were responsible for the pregnancy of one cow in the population of 1992. The total population included 49 males and 454 females. So only 33% of the males and 7% of the females had been active in breeding. Thirteen of the 33 females and nine of the 16 males had bred more than once, and of these three females and six males had bred five or more times.
A comparison of the age of mothers between working elephants in Burma (Schmidt and Khyne U Mar, 1996) and zoo elephants in Europe shows a shift towards lower ages of mothers in Europe (Figure 6). The majority of births in Europe happen in the age class of 11–20 years, and 5% of the females gave birth when they were younger than ten years. In Burma no mother was younger than ten years, and most births took place in the age class of 31 to 40 years (Fig. 5) (Schmidt and Khyne U Mar, 1996). So zoo elephants seem to become sexually mature earlier than working elephants in Burma. The youngest mother in a European zoo (Paris Vincennes) was six years old. In the working camps in Burma the youngest cow was 13 years old. Sukumar (1989) calculated the mean age of first calving in a wild population in south India to be 17–18 years. The corresponding value in European zoos is 16.3 years. This supports the assumption of earlier sexual maturity in European female elephants.
Figure 6. Age of mothers in Europe (white bars) and Burma (black bars) at time of birth relative to all births. For Europe 80 births in the period from 1902 to August 1996 (Haufellner et al., 1993; European Elephant Group, 1996), and for Burma 278 births in the period 1991–1995 (Schmidt and Khyne U Mar, 1996), are included.
On the other hand the age range over which births take place is much smaller in the captive population of Europe than of Burma (Fig. 6). In Burma cows become pregnant up to 50 or more years of age (Schmidt and Khyne U Mar, 1996). This reproductive capacity up to an age of over 50 years is also described for wild elephants (Sukumar, 1989). But the oldest mother in Europe was only 31 years. The low life expectancy of captive European elephants is surely involved in this result.
Another possible explanation for the lack of breeding success in females of higher ages lies in the composition of breeding pairs. Observation in the wild shows that only large and massive bulls are able to breed (Kurt, 1986; Sukumar, 1989). Subadult bulls are not accepted by the adult females, and are moreover suppressed by dominant older bulls. In the wild only bulls which are older than 20 or 25 are able to mate successfully (Sukumar, 1989). In European zoos, bulls' reproductive activity may continue up to the age of 50, but most fathers are in the age class of 11–20 (Figure 7). Compared to the situation in the wild, the fathers are relatively young. In regions where big bulls have been reduced in the wild population, because of poaching or other reasons, the cows accept younger bulls for breeding (Sukumar, 1989). This is comparable to the zoo situation, where no competition between bulls exists, because normally only one bull is kept in a zoo.
Figure 7. Age of fathers in Europe (1902–1996). The ages of fathers at time of birth are given relative to the whole number of births which took place in the period between 1902 and 1996 in Europe (Haufellner et al., 1993; European Elephant Group, 1996). At the x-axis the age classes are given, and the y-axis represents the percentages of fathers in each age class. Fifty-four births could be analysed for this graphic.
Regarding the age difference in breeding pairs in Europe, the bull is older than the female in 50% of cases, and the same age in 11%. The mean age difference in these pairs was 17.7 years. In 39% the male was younger than the female, with a mean age difference of 3.1 years. Male elephants are heavier (Kurt, 1994) and taller (Kurt, 1986) than female elephants of the same age. So female zoo elephants prefer taller and more massive bulls as breeding partners, although competition between bulls does not exist in zoos. In most cases these bulls are older than the females.
Thus, obviously, successful breeding in European zoos depends on the availability of females between 11 and at most 30 years, because most births take place in this age range, and of corresponding males who are older or at least of the same age as the available females, since in 61% of the breeding pairs in this century the bulls were older or of the same age as the females.
Future breeding capacity
Potential cows for future breeding are those which were younger than 20 years old in 1992, since in the past most births have taken place between 11 and 30 years, as Fig. 6 shows. There were 95 such females in 1992 (Fig. 1); but of these, only 34 were kept together with bulls who could be successful in breeding, because they had already bred or were older or of the same age as the females. There were 16 of these bulls. So 61 females which were younger than 20 in 1992, and 33 males out of the male population in 1992 (Fig. 1), had no possibility of breeding in the future. It is assumed that all bulls out of the population of 1992 are still potential breeders for the future, because past experience has shown that bulls are able to breed up to a high age (Fig. 7). The animals which have potential for breeding live in 16 zoos. The whole European population of Asian elephants is distributed over 110 zoos and 51 circuses. This means that only 10% of the zoos and circuses can participate in breeding.
Breeding in captivity does not depend only on the total number of animals. As shown above, another great problem is the distribution of the animals over different institutions. One of the tasks of the Asian Elephant EEP will be to solve this problem. At present the usual way is to transfer cows living in zoos or circuses without a male to zoos which keep bulls. The transferred females stay in the new zoo for a few months in the hope that they will be mated successfully. But so far only 20% of these transfers have resulted in pregnancies (Kurt, 1994). In the wild the males leave their family groups when they are mature, while the females stay for their whole life in the group in which they were born (Sukumar, 1989). Leaving their familiar group, where they have built up social relationships over several years, and integration into a unfamiliar group, is an unnatural situation for female elephants. The stress this involves for the females may perhaps account for the low breeding success of the transfers.
A more natural way to compensate for the unfortunate distribution of potential breeders in European zoos and circuses might be the transfer of bulls. This alternative has failed so far, because of the difficulties in the handling of bulls, as mentioned above. Some potential breeding bulls are kept without any females. Most of them are in the states of the former Soviet Union (Perm, Grodno, Kharkov, Kiev, Nikolayev, Yerevan, Karaganda). These bulls should be integrated into the EEP. Either these zoos should receive some females of an age of 10 to 30 years, or the bulls should be delivered to a zoo which keeps some young females without a male. But the additional keeping of males or females depends on the capacity of the zoos' existing enclosures. In most cases these are not suitable to house males or additional females, and often the extension of the enclosures is prevented by lack of either finance or available space.
So the conservation of the captive population of Asian elephants in Europe depends mainly on management decisions concerning the unfortunate distribution of potential breeders, both female and male. If we cannot solve these problems, the self-sustaining captive population demanded by the EEP will be no more than an illusion.
(1) The European population of Asian elephants mainly consists of females. Keeping of bulls is difficult because of the increased aggression during the musth phases. Only a few zoos with suitably secure enclosures are able to keep bulls.
(2) The majority of the elephants in European zoos and circuses are in the age range between 21 and 30 years.
(3) Life expectancy of elephants is significantly reduced in Europe.
(4) Breeding in Europe shows a very high mortality in the age class of 0–1 year caused by a high rate of stillborn calves and babies killed by their mothers.
(5) Females become sexually mature earlier than their conspecifics in both wild and captive populations in Asia. Reproductive activity of females in Europe stops around 30 years, while captive females in Asia are reproductive up to ages of 50 years and more.
(6) Future breeding in Europe mainly depends on management solutions for the disadvantageous distribution of potential breeders, both female and male, over different zoos and circuses.
I would like to thank Dr Fred Kurt for his advice and support. Dr Udo Ganslosser helped in reviewing the manuscript.
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Jeannette Schmid, Zoologisches Institut I, Universität Erlangen/Nürnberg, Staudtstr. 5, D-91058 Erlangen, Germany. Correspondence address: Schieffelingsweg 8, 53123 Bonn, Germany (Tel.: 0049–228–623060; E-mail: email@example.com).
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