The key to understanding how cooperative captive breeding programmes work, is the studbook. If threatened species are to be successfully maintained in zoos and other collections, these relatively small populations must be carefully managed.
The History of Studbooks
Since animals were first domesticated, differences between individuals of the same species were noted and often used selectively to improve stock, e.g. for improved milk or egg yields. Records of individuals were kept verbally at first but as numbers grew, by writing, and these written records effectively became the first studbooks. The first official studbook was the “General Studbook for Thoroughbred Horses” set up in England in 1791.
The first studbook for a wild animal in captivity was for the European bison. Heinz Heck published this studbook in 1932, when it was realised that this species was destined to become extinct unless captive populations were managed by some co-operative means.
From these origins, the studbook has come to be recognised as the essential tool in the co-ordinated and scientific management of an endangered or vulnerable species.
Studbooks are primarily a compilation and source of genealogical data of individual animals which make up a particular population. The last ten years have seen a rapid increase in the number of studbooks managed. Advances in identification of animals, sex determination and the increased use of computer software to assist record keeping and analysis have aided their development.
Setting up a studbook
The purpose of a studbook is to facilitate a well-managed captive population as conservation breeding must go hand-in-hand with field conservation. Data on the species’ status in the wild and in captivity must be included in the proposal for a studbook.
Proposals for new international studbooks must be submitted to IUCN/SSC and the World Association of Zoos and Aquaria (WAZA) and only with their endorsement can a studbook be established and officially accepted.
Other important aspects of the proposals must include the credentials of the petitioner(s), including the professional experience, academic qualifications, and a statement of guarantee that the petitioner has institutional support and the necessary resources, both financial and practical, to maintain and publish the studbook.
The studbook keeper must then obtain information by asking every collection that has ever kept that species for their records. These records will include information on specific events, such as births, deaths, and movements between collections; the information will also include parental information. The result should be a full genealogical history for, at the very least, every animal alive today.
Maximum genetic diversity
The key difference between the original studbooks for domestic stock and the modern studbook used for captive breeding is that the latter aim to maintain maximum genetic diversity and the behavioural characteristics of a species. This is different to the selective breeding in domestic stock, which accentuates certain characteristics some of which may be detrimental to the species if it were to live in the wild again.
In order to present a comprehensive record of a species the studbook must contain details of every individual animal, both living and dead, starting, where possible, with the original wild-caught animals, the founders.
A complete historical listing of all the animals in a studbook should be published every three years and annually there should be an update of which animals have been born, died, moved and which animals resided in which collections at the end of the year. Copies of updates and the studbook are sent to all current holders, coordinating bodies and other interested parties.
The detailed breakdown of each animal’s genetic history and an analysis of the inbreeding coefficient of each animal and those resulting in hypothetical pairings enables the studbook keeper to determine which individuals would be most suitable for breeding and those which would not. The studbook keeper also needs to determine the level of representation (or relatedness) of some animals within the captive population. For example if a good breeding pair are allowed to continue breeding, the genetic diversity of the whole group could be threatened by over representation of too few animals.
The Zoological Society of London regularly publishes the updated list of current international studbooks in the International Zoo Yearbook. For further information on studbooks, please contact the studbook keeper. Further information on European regional studbooks, including a list of studbook holders, is available on the EAZA website.
To enable zoo personnel to manage populations of threatened species in captivity efficiently, a number of computer software programmes have been developed to assist in genetic and demographic management (read more about Animal Management Software).