RESEARCH ARTICLE


Body Condition and Chronic stress in Urban and Rural Noisy Miners



Chela Powell, Alan Lill*, Christopher P. Johnstone
Wildlife Ecology, School of Biological Sciences, Monash University Clayton Campus, Victoria 3800, Australia


© 2012 Powell et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: (https://creativecommons.org/licenses/by/4.0/legalcode). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Wildlife Ecology, School of Biological Sciences, Monash University Clayton Campus, Victoria 3800, Australia; Tel: 61 03 99055664; Fax: 61 3 9905 5613; E-mail: Alan.Lill@monash.edu


Abstract

Cities are potentially stressful environments for birds for numerous reasons, including their high volumes of pedestrian and vehicular traffic. Native birds inhabiting cities tolerate such human disturbance, but may still potentially incur some cost that is reflected in body condition and the level of chronic stress experienced, unless they are inherently relatively insensitive to urban stressors. We compared body mass and condition, three erythrocyte variables and heterophil: lymphocyte ratios (HL) of adult Noisy miners (Manorina melanocephala) in urban Melbourne, Australia and its rural hinterland. Urban individuals had a significantly higher HL (mean 0.995) than rural con-specifics (0.719), suggesting that they may have been experiencing higher chronic stress levels. Body condition (mass-size residuals) and haematocrit were similar in urban and rural individuals, but urban individuals were a little heavier (~ 1%) and rural individuals had a 0.6 g dl higher whole blood haemoglobin concentration. There were no significant relationships between body condition indices and blood variables of the kind demonstrated in some bird species; their absence in Noisy miners may either reflect a lack of winter fattening or confirm that the occurrence of these relationships is species-specific.

Keywords: Noisy miner, heterophil, lymphocyte, chronic stress, body condition, erythrocyte variables, urban environment.