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Orangutans breeding and factors affecting their reproduction in captivity and in the wild
Kalkušová, Olga ; Kubík, Štěpán (advisor) ; Burešová, Eva (referee)
Information concerning orangutans living in the wild and the issue of their breeding has been summarized within the framework of this thesis. Orangutans in their natural habitats in tropical rainforests of Sumatra and Borneo are not subjected to the same influences as those bred in captivity. Their reproduction thus differs in certain aspects. Reproduction of orangutans in the wild is strongly influenced by their solitary way of life. Females are accompanied only by their young or eventually by other females and according to the studies they seek contact with males only in their period of rut. The contact is then limited to a period of time needed for copulation. One exception to this behaviour may be couples with juvenile males. After birth, the female looks after the young male for up to 8 years, having no rut during this period. The cycle of females living in the wild also shows dependency on the availability of food supply. Negative energy balance during which the cycle stops has been observed during periods of food scarcity. In the following period with abundance of food, the cycle is renewed again. The cycle renewal also occurs in cases when the female loses her young. As a consequence of these reproductive limitations females may give birth to 4 young at maximum in their life.
Guidelines have been drawn up for breeding in zoos which regulate the conditions and suitability of the exhibits so that they meet the orangutans needs. Their natural mental and physical activity is related to their health and natural behaviour. However, despite all efforts the zoos cannot provide the same conditions to the orangutans as those they would have in the wild. The forced increased socialization and contact with other individuals held in captivity may bring stress, stereotype behaviour and associated health problems which are rather frequent with orangutans bred in captivity.
According to the records in the pedigree books, the age of first reproduction and the interval between births were shorter in case of females kept in captivity. Even the keeping of males and females in one exhibit increases the probability of copulation and becoming pregnant. These changes also entail certain risks according to the studies. Breeding in captivity embodies higher mortality rate of young and adult animals. This is probably caused by young age of females at the birth and short intervals between births which are often shorter than 4 years. Females born in captivity also lack experience which they gain in the wild by learning and observing and are not able to take care of their young or refuse it later. Even females that got pregnant between the age of 11 and 14 have been described. However, such pregnancy poses a great risk for females and they die soon after birth or live much shorter. Young orangutans born in captivity were often taken away from their mothers. It is not very suitable on the one side, but on the other side, after having their young taken away from them, the females started a new, full-fledged cycle in a few weeks and could become pregnant again. However, as direct care of the young by humans has a negative effect, the young are often given back to their mothers which is successful in many cases.
Orangutans have been studied for more than 40 years and a lot of things concerning their breeding in captivity have changed during this time. Zoological gardens are trying to provide the orangutans as natural conditions as possible. It is necessary for the exhibits and the enrichment to provide enough physical and mental activities to the orangutans. Despite these efforts, the limited space and the related contacts between individuals may bring stressful situations. These are then manifested in the behaviour and health of the orangutans.
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