The Formation of a Bachelor Group of Gorillas at Loro Parque

BY MIKE DOWNMAN 
Assistant Curator, Loro Parque, Punta Brava, 
Puerto de la Cruz, Tenerife, Canary Islands, Spain 

Loro Parque, Tenerife, has housed western lowland gorillas since 1992. (Initially we were to have two groups. One was to contain animals from an under-represented bloodline in Europe, which we were to house on a temporary basis. The other group was to contain selected males to form a bachelor group. What follows is a history of the gorillas at Loro Parque from 1992 to the present time.

Our first gorillas came from the former East Berlin Zoo, Tierpark Berlin-Friedrichsfelde, on 12 November 1992, and consisted of 1.1 animals. The male, Bondo, was born in Gabon in c. 1969, and the female, Bianka, in Cameroon in c. 1972. A third animal, a silverbacked male, joined us from Amsterdam, but had been born in Wassenaaron 21 November 1983. After a while it was felt that this new silverback, called Yaounde, was probably better suited as a potential mate for Bianka, and so permission was obtained to introduce the two animals. Bondo was placed in an adjoining area, but maintained contact by auditory and visual means. This new pairing seemed to work, and although Bianka was not completely at ease initially, she soon became accustomed to Yaounde.

On 14 November 1992 the founders of the bachelor group arrived from Munich. Ivo was born there on 29 January 1988, and was hand-reared when his mother died shortly after giving birth. Noel was born on 28 December 1986 at La Palmyre, France. During his first three years of life he was housed with two orang-utans and one chimpanzee, which somewhat affected his behaviour. Happily, since his introduction to other gorillas he has progressed well and learned much.

The following 14 months saw no growth in the group, but on 27 February 1994 we suffered a loss. Bondo suddenly died. He had had a slight cold, but had appeared fine up until 17:00 hrs, when his keeper failed to get a response from him. The veterinarian at Loro Parque attended to him and administered drugs, but sadly he died at about 19:00 hrs. The cause of death was bilateral bronchopneumonia and septic shock. It transpired that Bondo had been suffering from a long-term bacterial infection which had colonised the respiratory epithelium. When he then suffered a viral bronchitis infection, the virus caused lesions in the epithelium, which were then invaded by the bacteria of the previous infection. This led to an extremely rapid spread of bacteria through the bloodstream and resulted in septicaemia, with cardiovascular effects, causing a rapid state of endotoxics hock.

After recovering from the sudden loss, we started to prepare for the next arrival. On 14 October 1994 a new male, a 22-year-old silverback called Schorsch, arrived from Nürnberg. He had been hand-reared after being rejected by his mother following his birth on 3 March 1972. Initially Schorsch came to us on a temporary basis, as the ape house at Nürnberg was being renovated. However, it was felt that he might be suitable for the bachelor project, and we were asked to keep him.

Three new animals arrived in 1995. On 13 July a young male called Pole Pole arrived from Munich. He had been born in Zürich on 28 December 1989, and had been hand-reared. The following day the last two arrived from Stuttgart. The youngest of the three was Rafiki, who is Pole Pole's brother, and was born in Zürich on 25 May 1991. Like his brother, he was hand-reared. The third animal was Maayabu, who was born in Stuttgart on 28 July 1988, and was raised by his mother. Shortly after Rafiki's arrival he was introduced to Pole Pole under the supervision of their former keepers, who had traveled with them. Maayabu ( was introduced to Ivo and Noel just a few days later. There was an immediate rapport between all three, so much so that it proved difficult to separate Maayabu at night. He is a very sociable animal, and very confident as well, but he did not like being separated from his new companions. He showed signs of stress and refused to eat, so after a day or two we decided to leave all three together, including night-times. This resulted in a much more relaxed and stress-free situation.

After almost two months of limited contact, it was decided to start the group introduction process. This took place in an off-exhibit area that is open to the elements. The first introduction was between Maayabu, Pole Pole and Rafiki. While there were no immediate problems, once again Maayabu became stressed by his separation from his two companions, and after two hours he was back with Ivo and Noel. The following day Noel was introduced to the youngsters, and this time it seemed to work well. He was very relaxed and showed great interest in his new playmates. They, on the other hand, seemed overwhelmed at first, and tried to keep their distance. This arrangement lasted two days, and we then reintroduced Maayabu, this time with success. Three days later it was the turn of Ivo to come into the group. He is without doubt the most intelligent gorilla at Loro Parque, and is also quite energetic and boisterous. Despite these last two characteristics he behaved well, and we were able to keep all five together all day.

The sixth member of the group, Schorsch, is a very solitary animal, and despite his size and silverback status is something of a 'gentle giant'. We were therefore fairly confident that he could be introduced safely, and this was achieved with no problems, save for Schorsch maintaining zero contact with everybody.

Understandably, any introduction programme is inevitably going to cause some disruption to an animal's daily routine, and with our gorillas it also made them nervous and excitable. When we were sure that they had calmed down they were allowed out into the exhibition terraces. The two terraces, with roughly a 60/40 split, form a multi-level exhibit with an area of 3,000 square meter. They contain free-access planted areas, protected areas (hot- wired), a large waterfall and stream (west terrace), large fallen tree trunks me of which bridges the stream, rock-work, climbing trees, small caves, and a grass/soil floor. The terraces were separated by a large rock wall. All the gorillas had previously been given access to the terraces on an individual basis. Schorsch was the only one to have problems with this.

He tried to avoid all contact with the grass at first, preferring to stayon the rocks or concrete at the bases of the walls. It was clear that he had not had experience of a natural floor surface before, and he did not like it. But with the aid of a little gentle coercion the keepers managed to get Schorsch to accept the grass, until it no longer bothered him.

When the six gorillas were first let out as a group, there were a few minor skirmishes in the first hour, but then they settled down. Rafiki was probably the most affected by this, and tried to maintain contact with the others, even if it meant having to chase after them.

At this point our two groups totalled eight animals (1.1 and 6.0), and they remained so until 17 April 1997 , when Bianka and Yaounde were sent to Nürnberg. Prior to this they had occupied the smaller east terrace. After their departure the dividing wall was knocked down, giving the bachelor group access to the full 2,000 square meter. They soon utilised this space; some individuals found their 'own' spot, and could be located simply by checking (these areas first. Bonds had also started to be formed, and it came as n, surprise to see the two younger ones, Pole Pole and Rafiki, become very close. All the others, with again the notable exception of Schorsch, became very sociable, and could often be seen playing together. Schorsch has always remained distant from the others, but has on occasions been 'persuaded' to play by Maayabu!

With all families, things are not always rosy, and so it was with our 'family'. Ivo has always had a reputation as a bit of a trouble-maker, and because of his boisterous nature he does like to throw his weight around This has caused some problems for us, but with keeper supervision nothing serious has occurred. Generally the group have settled well, and have adapted well to bachelorhood. We seem to have got a good combination of animals, and are very pleased with our first group.

Much has been said on the pros and cons of the formation of bachelor groups of gorillas, for example in International Zoo News (Gould, 1997; Greenwood, 1997; Moiser, 1997). Personally I believe that there is a place within a captive-breeding programme for such groups as ours. The reasoning behind this belief is based on the needs of the individual males, and the long-term requirements of the species. As males mature they are exposed to stress-inducing situations as they attempt to improve their positions within the group, mainly to gain breeding rights, and thus expose them- selves to acts of aggression from the dominant silverbacks. In captive situations this can be remedied by removing the younger male, and transferring him to another group or collection. If that male is then kept in a solitary state, this may lead to him becoming desocialised, which could be counter-productive should he later be brought back into a breeding situation (Johnstone-Scott, 1988). Also, it seems a retrograde step for such animals to be removed permanently from the gene pool. By creating a bachelor group, all these problems can be addressed. The animal can be with conspecifics of similar age, normal social skills can develop, and the individual will be available, if needed, to create new bloodlines. There is also the benefit of having well-adjusted males 'on standby' should another collection suffer the loss of one of its breeding animals. Bachelor groups are, I believe, a logical step to take in the captive management of gorillas.

When Loro Parque first decided to go into gorillas it seemed certain that we would be asked to form a bachelor group. This we have done, and it has been a success. A lot of credit must go to the gorilla staff for the way they have dealt with various problems. In a future article I shall give an update on our group, and report on their reaction to our attempts to naturalise the terraces.

References 
Gould, N. (1997): Editorial. International Zoo News 44 (6): 326. 
Greenwood, A.G. (1997): Letter to the editor. International Zoo News 44 (8): 480. 
Johnstone-Scott, R.A. (1988): The potential for establishing bachelor groups of western lowland gorillas Gorilla g. gorilla. Dodo, Journal of the Jersey Wildlife Preservation Trust 25: 61-66. 
Moiser, C.M. ( 1997): Letter to the editor. International Zoo News 44 (8): 480-481.



Reproduced with permission of International Zoo News.