Carcass feeding and euthanization

Carcass feeding at Copenhagen Zoo:

Finding and processing food is a very important part of the natural behaviour of any species and takes up quite a bit of time for the animals.
In Copenhagen Zoo enrichment and feeding behaviour is one of the major focus areas. The zookeepers spread the food in the enclosure, hang it from trees and branches, hide it in burrows and put it in feeders and automats that work on timers to accommodate a natural feeding time pattern.

One of the greatest enrichment efforts for the big carnivores is carcass feeding. By carcass feeding a lot of the animal’s natural feeding behaviour is supported: dragging, tearing with teeth and claws, using muscles in the jaws, neck and forelegs, grooming themselves thoroughly afterwards and so forth – this is enrichment that can last for days.

In Copenhagen Zoo we find carcass-feeding to be a good ethical choice when keeping great carnivores in captivity. Being fed with natural cuts of meat including skin and bones, the carnivores get to eat the way nature has evolved them to. This supports the animal’s natural behavior and it leaves the visitors with a scene that includes a much more natural, active and well-stimulated carnivore all together.

The visitors get to experience a piece of true carnivore behavior and what nature is also about.

Listed below are some facts and information about surplus animals and euthanizing:

  • Euthanizing does NOT conflict with high animal welfare. In cases where euthanizing is necessary it is carried out by professional veterinarians and the animals does not suffer any pain
  • Surplus animals are a natural phenomenon in the wild and are an unavoidable result of sound breeding management in captivity. If the animals are not allowed to mate we deprive the animal’s natural behaviour. Courting, sexual behaviour and parental care takes up a lot of time for most mammals, enriches them and the natural behaviour results in high animal welfare.
  • Animals only become surplus animals when they reach a certain age where they would have left the group anyway.
  • Surplus animals also occur in the wild where young animals often die of hunger or are killed by other predators. It can be difficult to understand why a Zoo chooses to breed the animals if there is a risk of getting surplus animals, but research shows that e.g. sexual behaviour and parental care is of most importance for the welfare of the animals. Copenhagen Zoo is a modern zoo and is – as any other research institution - run by facts and the latest behavioural research.


We take our responsibility for animal welfare very seriously. Our staffs are professionals and they continually working to improve the methods to increase the animals natural behaviour and to raise public awareness.

Enriching the animals - how?

A key point in the Zoo’s enrichment programme is that the animals must be able to spend a natural quantity of time on foraging and eating. Traditionally, feeding of animals in zoos was very little naturally stimulating; feed was served to the animals, processed and prepared in bowls, even though they spend most of their time finding feed in the wild.


Today the various species are fed in a way that satisfies their natural feeding bahaviour. As an example the animals are not fed at fixed times in which way the Zoo avoids that the animals adapt to the schedule and become restless when feeding time approaches.

The carnivores are fed with whole carcasses instead of traditional sliced meat. The time they need to eat the meat is naturally prolonged by fur, skin, bones and tendons. At the same time, it involves a wide variety of natural behavior in terms of using muscles and teeth and the grooming.

In the Zoo the leopards are fed carcasses of for instance rabbits and goats. The caracals, that are expert bird catchers are served dead hens hung in rubber bands and the lions are frequently served whole horses and cows. Through this method the lions are not only forced to spend time and skills on their feed – they also benefit in terms of having their internal rank confirmed or tested. Naturally, the keepers see to it that all lions get what they need.


The biology of most herbivores is adapted to spending most of their time foraging and eating. Some species grass all day while others eat leaves and twigs in dense forest. In the Zoo you often see lots of branches with and without leaves in the enclosures. The animals spend a lot of time eating both leaves and cortex. Furthermore, the herbivores have lots of lucerne and hay in feed racks and hay nets that make it possible for for instance giraffes and elephants to forage at a natural height.


Front edge enrichment
The mixture of species and groups is another key point in the Zoo’s enrichment programme. Copenhagen Zoo concentrates on keeping the animals within the right social environment. Some species are gregarious and prefer to live in groups. Within the group you see social behavior such as mutual grooming, establishing and maintaining of rank and common parental care. All behavioural elements that are vital to the wellbeing of the animals. Mantled baboon is a good example. They live together in small groups consisting of a dominating male, 5-8 females and their young. The group spends the day foraging, parenting and playing. At night several groups gather in trees or on rocks and the “night community” may count up to 200 individuals. Therefore, the Zoo always has a large group of mantled baboons.

Young as enrichment
Young, parenting and all the fuss it entails is another key point in fulfilling the animals’ need for natural behavior in the Zoo.

It is important that the animals can observe a natural breeding cycle; that they are able to breed at natural intervals, both in order to maintain a healthy population among the zoos and if the population is to serve as a reserve pool for possible reintroduction to the wild. The young also provide ample opportunity for natural behavior. The grown individuals need to spend time on mating and parenting and teaching the young how to behave in the group. The young are very curious and play with other members of the group.

The lions are a good example of enrichment provided by young. The females spend time and energy on letting the male know that they are ready for mating. Later on the females share the parenting which is an important part of almost all mammals’ behavioural patterns. Even though the lion is not an endangered species and not up for reintroduction to the wild, the Zoo always leaves the lions to breed at natural intervals. The lions in the Zoo are therefore supported in a life rich in natural challenges.


Enclosure design
In the planning of new enclosures the biology of the animals determines the physical elements of the enclosure.

If we for instance build a new enclosure for a bear the aim will be to meet the needs of a carnivore that is an opportunist, i.e. that searches, roams and digs all over the place in order to find whatever may turn up. This means that the enclosure may contain soft floor material in which feed may be buried.

Everywhere in the Zoo we have natural trunks for climbing, balance training, ripping and biting of cortex and maybe finding larvae and insects.

Barren tile floors have been replaced by chipped bark and in some places weeds and plants are allowed to grow wild. In the brown bear enclosure piles of brushwood are left for building caves and the keepers hide apples and the like in the brushwood and in feeders for the bears to spend time on finding and eating.

Except from benefitting the wellbeing of the animals the life-like enclosures are also a vital part of the nature interpretation in a modern zoo as they contribute to our understanding of the way of life of the individual species.   

Q & A to scientific director Bengt Holst

Why does Copenhagen Zoo euthanize healthy animals?

Copenhagen Zoo’s animals are part of an international breeding programme which aims at ensuring a healthy animal population in European zoos. This is done by constantly ensuring that only unrelated animals breed so that inbreeding is avoided. If an animal’s genes are well represented in a population further breeding with that particular animal is unwanted. When an animal's genes are well represented in the breeding programme and there is no place for the animal in another zoo, the European Breeding Programme has agreed that the animal is to be euthanized. This is a situation that we know from other group animals that breed well. When breeding success increases it is sometimes necessary to euthanize.

We see this as a positive sign and as an insurance that we in the future will have a healthy animal population in European zoos. The same type of management is used in deer parks where red deer and fallow deer are culled to keep the populations healthy. The most important factor must be that the animals are healthy physically and behaviourally and that they have a good life whilst they are living whether this life is long or short. This is something Copenhagen Zoo believes strongly in. 


Why are the animals not given contraceptives?

In Copenhagen Zoo we let the animals breed naturally. With naturally we mean that they will get young within the same intervals as they would in the wild. That means that the animals get to carry out their natural behaviours. Parental care is a big part of an animal’s behaviour. It is a 24 hour job in longer periods of their lives and we believe that they should still be able to carry out this type of behaviour also in captivity. Contraceptives have a number of unwanted side effects on the internal organs and we would therefore apply a poorer animal welfare if we did not euthanize.


Why not transfer the animal to a zoo which is not part of the breeding programme or to a zoo that is interested in getting the animal?  

Only zoos that follow certain rules can be part of international breeding programmes. In Europe this is only the zoos that are members of the European Association of Zoos and Aquaria (EAZA). EAZA is an association that counts just over 300 members.

As a member of EAZA you agree to the following rules of not selling animals, working on a scientific basis and ensuring animal welfare. The international breeding programmes are fully controlled and open and are collaborations between institutions that follow from the same set of rules. This is important for the breeding programmes to work.


Why can't the animal be released in the wild?

It is not easy to reintroduce an animal to the wild. Many factors have to be considered and these are described in detail in IUCN's Reintroduction Guidelines (IUCN: International Union for Conservation of Nature). You can not just set animals ‘free’ if there is no possibility of them surviving.  First of all you have to consider what made the animal endangered in the first place and whether this is still the case.

Another important factor is local support as it is the local community that has to live with the animals. Unless it is part of an official release programme animals are not reintroduced. The natural habitats will be full of dangers and challenges so the animals that evidently are part of a reintroduction programme will be carefully selected to increase the chance of survival.


What does Copenhagen Zoo do with the dead animals?

After euthanasia the animal will be autopsied as we do with all our animals. That way we will collect important knowledge about the animal – knowledge that can benefit other animals of the same species. In case of euthanizing for example an antelope, horse or giraffe, the carcass will be used as food for the Zoo’s carnivores. When animals are euthanized with an overdose of aesthetic it is not possible to use the remains for food. However if the animal is first anaesthetized and then put down with a bolt pistol (same procedure as with horses and cows) it can be given to the carnivores.

Why does Copenhagen Zoo do public autopsies?

At Copenhagen Zoo we perform autopsies on all animals that die - from the smallest mouse to antelopes and elephants. We do this in order to gain new knowledge about the animals and to prevent diseases. Sometime, when we need to perform an autopsy, we invite our guests to observe our vets conducting the important work.

The vets are good communicators and during the autopsy they explain what we see, and how the whole organism works in an educational effort directed towards our guests. We are always careful to inform our guests beforehand that the process might be considered overwhelming for some and what they can expect if they chose to attend the autopsy.

By scientific director Bengt Holst


A lot has been said about the euthanasia of the above mentioned giraffe. People and organisations from all over the world have stated their criticque or support of the action, and as so often happens there have also been a lot of misunderstandings. Consequently there is a need for clarification.

In the article scientific director Bengt Holst has described what REALLY happened as well as the background for the decisions.

The three main points of criticism were:

  • Euthanasia/culling of a 2 year old male giraffe
  • Inviting the public to watch the autopsy
  • Feeding the carcass to the lions

Please find the answers in the full article here: