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Consequences of captivity in a mammal
Research Project: Behavioural and fitness consequences of captivity in a mammal
The major aims of zoo breeding programs are to maintain healthy captive populations as insurance against extinction in the wild, and to preserve the option of species reintroduction.
Reintroduction programs are a high profile and potentially controversial method for species conservation which means many endangered species may spend several generations in captivity before being released into the wild.
Research shows that captive-bred animals have less success compared with translocated wild animals. This may be due to a reduction in the fitness of animals (ie. the ability of individuals to survive and reproduce in the wild) over successive generations in captivity.
Living in captivity will lead to some degree of adaptation to the captive environment and this effect is likely to become more pronounced over successive generations. It is therefore essential that conservation biologists gain a better understanding of not only how captivity alters fitness traits desirable in the wild, but also the time-frame in which these changes are likely to occur.
To establish a captive population of a mammal model (the House Mouse) to assess experimentally the fitness costs associated with habituation to short-term maintenance in captivity.
The specific aims were to (i) measure changes in behaviour of house mice over generations in captivity and (ii) quantify the consequences of captivity on the fitness of captive-born mice relative to wild-bred mice during re-introductions.
- Behavioural tests were conducted with the founder (wild born), first generation and second generation captive mice to examine variations in boldness and exploration
- First and then second generation mice from the captive population were released simultaneously into a large enclosures with wild-caught mice
- Released mice were regularly assessed for survival, weight, condition and reproduction
- Wild founder mice displayed different behaviours to first and second generation captive-born mice, with founder mice investigating more and captive-born mice hiding more
- Captive-born mice were heavier than wild mice after release and had more pregnancies
- Captive-born mice had lower survival than wild mice after release
- Results indicate that after only one generation of captivity there are differences in behaviour, reproduce output and survival compared to wild mice. This emphasises the need to maintain wild behavioural traits, even during short term periods of captivity.
Primary researcher: Tim Jessop (Department of Zoology, University of Melbourne)
Participating organisations: Zoos Victoria; University of Melbourne