The effect of diet on growth and reproduction of western swamp tortoises (Pseudemydura umbrina) at Perth zoo

Date of Award


Document Type



Edith Cowan University

Degree Name

Master of Science (Biological Sciences)


School of Science

First Supervisor

Pierre Horwitz

Second Supervisor

Peter Mawson

Third Supervisor

Johnny Lo


The captive breeding for release program at Perth Zoo for the Western Swamp Tortoise (Pseudemydura umbrina) makes an essential contribution to the species’ long-term conservation prospects. In doing so, the program has generated a considerable database on the biology of the captive population. This study investigated retrospective data collected across a total of 9 breeding seasons (years) to determine the factors that influence the species’ growth and reproduction in captivity. Diet was the main factor focussed on since nutrition provision is a key husbandry area that is made difficult trying to replicate a species’ highly specialised wild diet in captivity to a large-scale breeding program. Minor nutritional differences were found between the predominantly red-meat and white-meat only captive diets; the white diet had slightly higher protein and protein to energy ratio, while the red diet had a higher fat content. Captive diets fed to offspring did not produce consistent differences for all juvenile growth or aestivation periods. Where differences did occur (however inconsistent), the red diet yielded a significantly higher specific growth rate than the white diet. Captive diet fed to breeding females was a more prevalent factor across the reproductive variables with an overall, but again not entirely congruent trend, of the white diet having significantly higher reproductive fitness than the red diet. Given the species’ abilities to reproduce and grow in captivity regardless of minimal nutritional differences, the white captive diet is recommended as more appropriate to the breeding program overall. Of all the factors examined, the variability between breeding seasons was the most consistently significant difference for growth and reproductive variables. The findings of the thesis on the multi-factorial relationship between nutrition, growth and reproduction, highlight the areas still needing further research, such as the environmental factors in captive breeding settings themselves.



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