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Evolutionary, molecular and comparative zoology
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RESEARCH ARTICLE
Contents Vol 55(4)

Activity-related variation in blood parameters associated with oxygen transport and chronic stress in little penguins

Louise Mortimer A and Alan Lill A B C
+ Author Affiliations
- Author Affiliations

A Wildlife Ecology Research Group, School of Biological Sciences, Monash University, Clayton, Vic. 3800, Australia.

B School of Psychology, Psychiatry and Psychological Medicine, Monash University, Clayton, Vic. 3800, Australia.

C Corresponding author. Email: alan.lill@sci.monash.edu.au

Australian Journal of Zoology 55(4) 249-256 https://doi.org/10.1071/ZO07030
Submitted: 15 May 2007  Accepted: 14 August 2007   Published: 24 September 2007

Abstract

Some birds facing energy ‘bottlenecks’ display elevated oxidative metabolism and oxygen delivery to tissues and could be particularly susceptible to chronic stress. We examined whether there was evidence for such trends in little penguins (Eudyptula minor) over the period from breeding to the post-moulting stage and particularly during the onshore moult-fast. Penguin parents contribute equally to incubation, brooding and brood provisioning. A few weeks post-breeding, adults undergo a protracted, terrestrial moult-fast and then make brief visits to the colony during the post-moulting stage. Provisioning nestling(s) and moulting could theoretically be particularly energetically and nutritionally demanding. We determined for adults whether mass, a body condition index and blood parameters influencing vascular oxygen carrying capacity (hematocrit, Hct; whole blood haemoglobin, Hb) and indicating chronic stress (leukocyte count, WBC; heterophil/lymphocyte ratio, H/L) varied from August to May in a manner reflecting likely variation in energy and nutrient demand. Female mass and body condition index decreased significantly between the incubation and guard stages, before returning to incubation levels between the guard and post-guard nestling stages. Both parameters declined to their lowest levels between the post-guard and moult stages, before increasing to levels comparable with those during nestling care between the moult and post-moult stages. Blood parameters in both sexes exhibited temporal variation similar to that in female mass and body condition index, declining to their lowest levels during moult and increasing after the moult to levels comparable with those during breeding. Results indicated that the period of most intense provisioning of nestlings was associated with a decrease in blood oxygen carrying capacity, but no pronounced change in chronic stress indicators. However, the penguin’s moult-fast involved a loss of female body condition and, in both sexes, a reduction in body mass, vascular oxygen carrying capacity and possibly specific immune competence. Thus, regulation of human disturbance in accessible little penguin colonies may be particularly important during moult.


Acknowledgements

We are grateful to Phillip Island Nature Park and the Victorian Department of Sustainability and Environment for permitting this study, which was approved by the Monash University School of Biological Sciences Animal Ethics Committee. We thank the following field volunteers: Leanne Renwick, Amanda Schaar-Schmidt, Matthew Johnson, Pat Mortimer and Alister Jenkins. We also thank Peter Dann, Roz Jessop, Marg Healy and Megan Price for technical advice and Murray Logan for statistical advice.


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