USING A MODEL SPECIES TO IMPROVE THE OUTCOMES OF THREATENED SPECIES REINTRODUCTION

A litter of second-generation captive-bred mice.           Photo: M. Parrott 

Many populations of wild species are declining. One increasingly important management option is to maintain long-term captive populations and reintroduce animals into the wild.

Unfortunately, reintroduced animals often do not survive and reproduce as well as their wild counterparts, and so reintroductions are not always successful. Captive-bred animals are likely to be inbred and are often reared in captivity for multiple generations. For example, threatened native species are often bred in captivity for more than 10 generations.

For captive breeding programs to be more successful, experimental husbandry techniques must be developed that:

1. Identify the rate at which fitness is lost in captivity.
2. Maintain individual fitness above such thresholds sufficient to improve population recovery.

A collaborative research project between Zoos Victoria and the University of Melbourne is assessing the short- and long-term fitness costs of captive breeding programs.

AIMS

This project aims to establish experimental captive breeding populations of mice (Mus musculus) as a model to monitor fitness changes arising from captivity in threatened species.

This will allow us to understand how captivity changes the life-history processes of a population, and to independently quantify the consequences of inbreeding and captive selection related changes on the relative fitness of released animals.

METHODS

Wild mice from Werribee Open Range Zoo have been used to establish a long-term captive breeding colony.

The behaviour of each generation of captive-bred mice will be tested in new situations and against natural predator threats (tiger snake scent and the presence of owls).

Captive-bred mice will then be released into 12 new enclosures at Werribee Open Range Zoo and competed with wild-caught mice to measure their relative fitness. Factors measured will include survival, dispersal, social dominance and reproductive contributions (via genetic paternity assessment). Trials will be conducted and compared across multiple generations of captive-bred mice.

RESULTS

The captive breeding colony of mice has been successfully established; second-generation mice were born in January 2010. The behavioural analyses of wild-caught and first generation captive-bred animals have been completed.

The new enclosures are currently being constructed at Werribee Open Range Zoo and releases of mice will begin in the next few months.

OUTCOMES

Information gained from this project will help us make more informed decisions about the costs and benefits of captive breeding and reintroduction programs for threatened species. It will also lead to the development of husbandry protocols that improve the retention of wild attributes in captivity. This will hopefully improve the capacity of captive breeding programs to aid the recovery of threatened species.

FOR MORE INFORMATION

- on this research project - click here to email Dr Tim Jessop (Principal Investigator).

- on Zoos Victoria's threatened species breeding programs - click here.