Only a few weeks before I was to take up my position on November 1st, 1993 as director at Duisburg Zoo, my boss at that time, Dr. Hans Frädrich, director of the Zoological Garden Berlin, declined for a variety of reasons an offer from San Diego Zoo to acquire two koalas from their breeding colony. Almost as a congratulation on my new position, Dr. Frädrich provided me with the contract option with San Diego Zoo.

Soon thereafter, I was able to convince my colleagues of the Duisburg Zoo directorial board and the board of trustees to obtain two koalas from San Diego and to bring them to Duisburg for the summer period of 1994. This action was intended to focus on the need for worldwide nature and species conservation and an approximate 200,000 DM were invested in a facility for koala husbandry which would satisfy modern zoo standards.

Two independent situations -as so often in life, guided by pure chance- contributed to the establishment of successful koala husbandry and breeding in Duisburg.

Through Mr. Friedhelm Rosendahl, president of the society "Friends of Duisburg Zoo", I came into contact with the architect Mr. Peter Rasbach, a member of this society, who enthusiastically joined my ideas. He planned and later on contributed to the rebuilding of an old shed into a very modern koala-house, free of charge and with the help of several enterprises and the zoo craftsmen.

Searching for possibilities to ensure constant food supply, I came into contact with Dr. Thomas Immelmann of the airline LTU from Düsseldorf who turned out to be the son of the late Professor Dr. Klaus Immelmann, a well-known ethologist. Dr. Immelmann enthusiastically supported the Koala project and was capable of convincing the direction of LTU to provide significant sponsoring. Since then, LTU has transported free of charge 4 koalas -each taking two passenger seats- as well as keepers, scientists from the zoos of San Diego and Duisburg and architects between the United States and Düsseldorf.

Moreover, LTU made a commitment to deliver the necessary eucalyptus twice a week from Miami to Düsseldorf at no cost. On May 26, 1994 the male koalas KAMBARA (born July 20, 1992) and BLINKY BILL (born in 1983) arrived at the airport in Düsseldorf and were met by a large gathering of press representatives. Anticipating the high interest of the press, the airplane had been parked away from the usual airport building for the passengers. Surprised by this overwhelming attention, responsible keeper from San Diego Zoo agreed to the presentation of the VIP-travellers on the gangway against the usual procedure. The experienced zoo keeper Franz Schramke from Duisburg who had become responsible for koala husbandry remained calm. Franz Schramke had learned the details of husbandry and keeping of koalas in San Diego for 14 days and had travelled with the animals from San Diego to Duisburg. At this point I would like to thank Mr. Schramke for his high engagement and excellent work.

It was thanks to his performance, his innovative ideas for the design of the interior and exterior exhibits and his feeling for the individual animals that good result in keeping koalas at Duisburg Zoo were achieved quickly and the idea rose of a permanent keeping and -if possible- of breeding this species. After the critical evaluation, even the experts from San Diego Zoo could be convinced of the good development of the two koalas in Duisburg, and as a consequence on 17 March, 1995 the elderly koala BLINKY BILL was exchanged for a young female called YURI. Theoretically, this provided the basis for breeding.

Exhibit design

Koalas are semi-social animals. Male individuals live alone in their own territories except for short periods during sexual activity. Such territory often consists of only one large eucalyptus tree providing the necessary food resources. The female animals require separate food-territories. If such territory provides sufficient food, female, offspring will often be allowed to stay within the territory. In times of food scarcity the young progeny are usually driven out of the territory.

For keeping koalas in human care, these facts lead to the conclusion that male koalas need to be kept permanently separate from females. With sufficient exhibit size it is possible to establish individual small size territories for several -especially related- females to be kept in one exhibit.

Our animals have been provided with two exhibits of 4 x 6 square meters, separated from each other by glass wall and an additional glass wall towards the visitors. The glass is designed in such way as to provide 100 % acoustic insulation. The visitors area is furnished with three step-like platforms, the highest being 1.5 m above exhibit hight. Additionally, the visitors area is limited by a moat containing plants and a fence. Disturbance of the animals by knocking on the glass is herewith excluded. On the walls of the entrance and visitors area there are detailed information panels on the history, life history and biology of these animals.

The dimmed light and general ambience of the visitors area has an atmosphere of calmness which even makes noisy school classes behave calmly. The exhibit and visitor area has video surveillance. The recordings are stored on video cassettes permanently. This allowed a detailed examination of any potentially abnormal behaviour of the animals as well as their feeding. The use of flashes for cameras is prohibited. TV screens and information panels provide insights on birth and breeding behaviour of koalas. The floor of the exhibits is of extremely smooth concrete and remains uncovered for hygienic reasons. Only during the nursing period, branches of eucalyptus are distributed around the sitting trees of the koalas to avoid injuries during a potential fall of the joey during his first leave from the mother's pouch. Every exhibit has four climbing trees which are connected by branches in several ways. The wood consists mainly of oak, because it has a durable and non-slippery bark. The walls of the exhibit are covered up to a hight of 1.5 m with an imitation rockery which cannot be climbed by the animals. Above that, the wall is covered by natural wood panels and a variety of plants. The roof of the exhibit is of transparent material. Additionally, both exhibits are equipped with an computer controlled HQI lamps which simulate a natural increase and decrease of light during dusk and dawn especially during the short and dark winter days (sponsored by the enterprise Le Grand). During night time a minimum illumination assures adequate video control. The exhibit and the visitors area have a separate air condition. The temperature in the exhibits is kept permanently on 22° C while the mean relative humility is kept between 60 and 70 %. The keeper/service area contains separation and quarantine facilities and a large cold storage to provide fresh eucalyptus at all times; it was extended in 1996 by adding a large store room. Mainly on his own initiative, Mr. Schramke designed an exterior exhibit of approximately 50 m2 in summer 1996. This exhibit combines a nice atmosphere for the visitors with suitable facilities for the animals: copious vegetation, several climbing trees of 3 m hight and with large and varied branching, additional shading and a moat of 1.5 m broad and 40 cm deep. A direct communication with the house does not exist and the animals have to be transported to the exterior exhibit by hand.

Husbandry

To provide a stress-free handling of the animals, the koalas have to be used to body contact with the keepers. This is necessary for pouch controls as well as regular weighing. As another consequence of regular body contact, the animals appreciate fur care. For most handling strong leather gloves are necessary because of their sharp claws and strong bite.

Feeding

As mentioned before, eucalyptus is brought over from a eucalyptus farm close to Miami twice a week. It is kept wet and is flown to Düsseldorf packed, to be collected by a driver or the keeper at the airport. Each delivery consists of several parcels with a wet weight ranging between 25 and 30 kilos in total. Depending on the availability the following eucalyptus species are delivered: tereticornis, grandis, punctata, citriodora, camaldulensis, robusta, botryoides, viminalis, rudis, saligna, creba. According to their respective stadium of growth, different species of eucalyptus are preferred by the animals. This follows a yearly cycle, e.g. in different times on the year different eucalyptus is generally preferred. Some small leaves species as citriodora are more delicate and do not have as good storing qualities as larger leaved, robust species. The branches of eucalyptus have to be kept fresh in the refrigerator inside a water-filled container at 8° C for three to four days. To allow photosynthesis the refrigerator is illuminated. Food is provided to the animals around 9.30 a.m. and in the afternoon. The food is placed in water-filled containers on different supports in those branches located next to good seating positions. Different species are provided in each container. The feeding behaviour of individuals differs strongly for unknown reason. Similarly the feeding times can vary significantly, as for example KANGULANDAI (the first born), daughter of YURI, is generally more active in feeding than her mother. The animals are provided with water in a stable container on the floor which can not be tilted. While drinking could not be observed in the animals during day time, the video night surveillance shows that they use the offered water. Still, the largest part of their need for fluids is covered by their food. The faecal balls of koalas are kidney-shaped and of the size of beans. For better control of the foods digestion (Eucalyptus contains only approximately 70 percent of the energy of comparable plants) the total of the faecal balls is collected and weighted by the keeper. Usually the faeces is hard and only exceptionally somewhat softer. The firmness of the faeces may depend on the amount of the young shoots -which contain more fluid- have been eaten. Only in very few species the branches themselves are eaten. While faeces is deposited with the animal sitting in the branches, the koalas leave their tree for urination on the floor. Only during her pregnancy with the joey in the pouch, the mother did not climb down to the floor, but only to lower branches to urinate. This behaviour of urination may indicate -at least in male individuals- an additional marking of their territory. While faeces are dropped approximately four times during daylight hours alone, the animals only leave their climbing trees two to three times in 24 hours to urinate.

Weight

In comparison, the food of the koala only provides 70 % of the energy of a comparable sized mammal with different vegetarian food. Stress situations, reduced food quality as well as wilted food lead to a rather rapid loss of weight which can not be noted due to the thick fur -not even by an experienced keeper. As koalas hardly have any fat, muscle substance is broken down during weight loss. Therefore, regular weight control is important and performed every wednesday and sunday. For this purpose we use an electronic weighing scale, accurate to 1 gram, which was sponsored by the enterprise "Waagen-Service Lindemann". On this weighing scale a special device is placed. It consists of a non-slippery floor with a branch on top on which the animals can be placed by hand. A large display shows the weight to the keeper and the public. Such protocol necessary for husbandry has become a true attraction for the public. On October 11, 1996 the breeding male KAMBARA had a weight of 7105 g at the age of 4 years and 3 months, while the just arrived male BIRUBI (cross of the south) did weigh 5800 g at the same time. The female YURI arrived in Duisburg at an age of 23 months and her weight was 4450 g, on October 11, 1996 her weight was 5150 g. The first weighing of her offspring KANGULANDAI took place on January 10, 1996, and gave a weight of 700 g. On 11 October, 1996 she weighted 4760 g. The development of her weight is illustrated in figure 2.

Breeding

Unlike in the wild where the male itself approaches a female in heat after having first established vocal contact, we just placed the menstruating female into the exhibit of KAMBARA on the evening of May 4, 1995. This was Yuri's second menstruation at Duisburg Zoo. The first one we had ignored on purpose to allow an adequate adaption to her new home. The second heat took place 30 days later and was very obvious due to the behaviour of male KAMBARA. In the three days previous to the mating KAMBARA had been very active mainly during the night, walking along the glass-wall separation of the exhibits and bellowing. Furthermore, an increase in urination was noted. If we had taken the male to the female's exhibit for mating, it was feared that KAMBARA would have taken too much time to mark the new territory before the mating. To not distract him from his primary task, the female was placed into his exhibit. Our major concern was that during the mating one or both animals may not have a firm grip on the branches and fall to the floor. For a neutral observer it may have been a funny picture to see keeper, scientific staff and director in a praying position: with their hands reached out under the climbing tree of the koalas.

Only a few seconds after being placed together, KAMBARA climbed towards YURI and, after two unsuccessful attempts, managed to manoeuvre himself and the female into the proper position. The mating took place at 6.45 p.m.. The female had a strong hold with all four limps on the branch while the male held her with his front limbs; his hind feet were firmly attached to the branch. The position of both animals was very secure, also because the female tolerated the approach of the male without any resistance. The mating itself took only a few seconds after which the female started showing a strong antagonistic behaviour. At this point we were forced to remove the female back to her own exhibit.

Exactly 34 days and 30 minutes after the mating on June 7, 1995 at 7.15 a young koala was born and left an obvious trace of mucus and blood on the belly of her mother while climbing its way from the birth opening to the opening of the pouch. Appropriate to the importance of the event, half an hour later a bottle of champaign was provided by the director to celebrate the happy event while the mother - unaware of the importance of the moment - had fall asleep. Secretly the direction and the koala-keeper were inspired by a euphoric hope but publicly a certain pessimism was shown. This was due to the fact that we were aware that more than a third of the joeys do not survive the first days in the pouch. Additionally, further mortality occurs during the first climbing attempts of the joey on the mothers body by falling down and when the food is changed from milk to the so called "pap feeding".

Our hope for a healthy, growing neonate in the pouch was confirmed on August 4, 1995, when at 7.30 a.m. some well visible moves in the pouch were observed. Only a few days after the birth the hope for the survival of a youngster in the pouch rose as the mother had taken an obviously different position of sitting. Normally YURI would place her belly very close to the wood during her sleep; after birth, an obvious distance of the pouch from the wood was kept. While individual extremities of the joey had been seen outside the pouch of the mother for short periods of time previously, it was first on the afternoon of October 23rd, around 4 p.m., -140 days after the birth- that the almost naked head became visible in the pouch opening. Although the joey only left the pouch partially, on day 175, Mr. Schramke was able to observe a pouch on it's belly. This observation confirmed we were lucky to have the first successful breeding of a koala in Europe: a female named KANGULANDAI.

On November 29, 1995, day 176, it was first noted that the anal region of YURI was covered with smear. From this time on we anxiously expected a negative reaction to the change of food from exclusively milk to "pap-feeding". "Pap feeding" means that the mother offers the joey semi-digested food in the form of soft faecal balls, which in contrast to normal faecal balls contain a large percentage of cellulose-cleaving microorganisms. During several weeks the joey is "vaccinated" through this food with the missing microorganisms for gut digestion. We observed that the joey -with his hind-quarters remaining in the pouch- squashed the soft faecal balls with his nose and absorbed the created paste from the anal pouch by licking. On day 184 the video recordings show the first complete exit from the pouch. It took only a few days until the young koala lady -completely covered with hair by then- made trips over the body of her mother with alarming acrobatics. The first attempts to climb on the back of the mother were very stressfull for the mother as the young -with its sharps claws on the mothers face and nose- tried to reach the neck by climbing on the face. On day 189 around 6 p.m. the joey was observed walking on a branch without the mother for the first time and taking a bite of eucalyptus which was spat out immediately. At first, such excursions took only a few minutes and with every disturbance it would jump back into the pouch immediately, despite not fitting inside with it's whole body any more. On day 194 the first longer walk was observed between 2:00 and 2:17 hours p.m. mainly on the body of the mother. From then on it developed further, steadily increasing its weight and undertaking independent walks and starting to feed on eucalyptus. During this process, the mother suffered a considerable weight loss and for her convalescence the youngster was separated on June 30, 1996 for several weeks.

On October 11, 1996, a young koala male BIRUBI, born on October 26, 1994, arrived from San Diego to Düsseldorf as VIP on the airplane of the airline LTU. According to his status as -Very Important Person/Koala- he was received in the koala house at Duisburg Zoo by an astonishingly large number of press representatives. BIRUBI stems from a different genetic line and will be the mating partner of KANGULANDAI in the future.

On November 28, 1996, YURI mated with KAMBARA once again. At this point, she had a weight of 4900 g. On January 1, 1997, a birth was recorded, but only a few weeks later it was discovered that the pouch of YURI was empty. The weight controls of these weeks show that there was no significant increase in weight, which fluctuated around 5000 g.

Eight weeks later YURI, now weighing 5400 g., was again taken to mate with KAMBARA. As previously, with the pregnancy of KANGULANDAI, a steady increase of weight was recorded in subsequent weeks and until now, this tendency continues and indicates a good development of the joey. The weight controls during the first weeks post partum therefore give a reliable indication of the successful development of koala young still invisible in the pouch.