Species management
The breeding of insurance populations for species conservation is a complex process. This is because we need to keep populations genetically diverse and healthy.
In nature, there are three processes that regulate populations: reproduction, migration and death.
- Reproduction: allows the population to grow.
- Migration: introduces variety to the population. Where the social structure of the species allows, young animals migrate to other areas on reaching adulthood.
- Death: shrinks the population. Animals starve or die of thirst, or fall victim to diseases/epidemics or predators, which usually prey animals that are young, sick, weak or old animals.
These processes do not happen in zoos, so humans have to initiate and control them.
Reproduction
There are three reasons why it is important for animals to be able to reproduce without restriction.
- First, reproduction is a basic need of animals. In social animals, rearing young is an important group task that the animals have to learn. They can only do this if they actually have offspring to care for.
- Without sufficient offspring, populations become over-aged. Aged populations can no longer grow on their own in the long term and ensure their survival.
- Contraceptives can lead to permanent sterility and/or behavioural changes in female animals.
Unrestricted reproduction causes the animal group to grow, which is why we rely on two other processes: migration and death.
Migration
Zoos imitate migration by exchanging animals with each other. However, space in zoological institutions is limited. Not every animal will have a suitable release point,
which is why we need the third process: death.
Death
The zoo will put down an animal only after a comprehensive assessment.
The decision to put an animal down is made if …
- the animal can no longer be used for the continued existence of the zoo population within the coordinated conservation breeding programme
- and there is no suitable release point available that meets the animal’s needs.
Animals are put down without fear or pain in accordance with the requirements of the Swiss Animal Welfare Ordinance. Where possible, the animals we put down are given as feed within the zoo or offered to researchers if they are interested in that particular species.
For the population, deaths in the zoo corresponds to the natural mortality rate of animals in nature.
Animal population changes in the zoo
The following overviews provide information about population changes at Zoo Zurich – reproduction (birth/hatching), migration (arrival and release) and death.
