Do metabolism and contour plumage insulation vary in response to seasonal energy bottlenecks in superb fairy-wrens?
Alan Lill A B C , Jeffrey Box A and John Baldwin AA Wildlife Ecology Research Group, School of Biological Sciences, Monash University, Clayton, Vic. 3800, Australia.
B School of Psychiatry, Psychology and Psychological Medicine, Monash University, Clayton, Vic. 3800, Australia.
C Corresponding author. Email: alan.lill@sci.monash.edu.au
Australian Journal of Zoology 54(1) 23-30 https://doi.org/10.1071/ZO05029
Submitted: 9 June 2005 Accepted: 5 January 2006 Published: 23 March 2006
Abstract
Many small birds living at mid-to-high latitudes in the North Temperate Zone display seasonal increases in general metabolism and plumage insulation. We examined whether superb fairy-wrens at low altitude in temperate Australia, where winter is milder and the winter–spring transition less pronounced, exhibited similar adjustments. Their oxygen-consumption rate at ambient temperatures in and below their thermoneutral range was measured overnight in winter, spring and summer. Contour plumage mass was also compared in individuals caught in all seasons of the year. Resting-phase metabolic rate in the thermoneutral zone did not vary seasonally. The relationship between ambient temperature and whole-body metabolic rate below lower critical temperature differed in summer and winter, but the regression for spring did not differ from those for summer or winter. Plumage mass was greater (4.04% v. 2.64% of body mass) and calculated whole-bird wet thermal conductance lower (1.55 v. 2.24 mL O2 bird–1 h–1 °C–1) in winter than in summer. Enhanced plumage insulation could have improved heat conservation in autumn and winter. No increase in standard metabolism occurred in winter, perhaps because this season is relatively mild at low altitude in temperate Australia. However, superb fairy-wrens at 37°S operated below their predicted lower critical temperature for most of winter and the early breeding season, so they have presumably evolved as yet unidentified mechanisms for coping with the energy bottlenecks encountered then.
Acknowledgments
Our research was approved by the Monash University School of Biological Sciences Animal Ethics Committee. We are grateful to Peter Fell for valuable field and laboratory assistance.
Ambrose, S. J. , and Bradshaw, S. D. (1988). Seasonal changes in standard metabolic rates in white-browed scrubwren (Sericornis frontalis) from arid, semi-arid and mesic environments. Comparative Biochemistry and Physiology 89, 79–83.
| PubMed |
Box, J. , Lill, A. , and Baldwin, J. (2002). Seasonal variation in body mass and blood oxygen carrying capacity of the superb fairy-wren (Malurus cyaneus). Australian Journal of Zoology 50, 313–323.
| Crossref | GoogleScholarGoogle Scholar |
Carey, C. , Dawson, W. R. , Maxwell, L. C. , and Faulkner, J. A. (1978). Seasonal acclimatization to temperature in cardueline finches. II. Changes in body composition and mass in relation to season and acute cold stress. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 125, 101–113.
| Crossref | GoogleScholarGoogle Scholar |
Chambers, L. E. , Hughes, L. , and Weston, M. A. (2005). Climate change and its impact on Australia’s avifauna. Emu 105, 1–20.
| Crossref | GoogleScholarGoogle Scholar |
Dawson, W. R. , Marsh, R. L. , Buttemer, W. A. , and Carey, C. (1983). Seasonal and geographic variation of cold resistance in house finches Carpodacus mexicanus. Physiological Zoology 56, 353–369.
Lill, A. (1991). Behavioural energetics of overwintering in the rifleman, Acanthisitta chloris. Australian Journal of Zoology 39, 643–654.
| Crossref | GoogleScholarGoogle Scholar |
McMillen, R. E. (1985). Energetic patterns and lifestyle in the Meliphagidae. New Zealand Journal of Zoology 12, 623–629.
Piersma, T. (2002). Energetic bottlenecks and other design constraints in avian annual cycles. Integrative and Comparative Biology 42, 51–67.
| Crossref | GoogleScholarGoogle Scholar |
Rezende, E. L. , Swanson, D. L. , Novoa, F. F. , and Bozinovic, F. (2002). Passerines versus nonpasserines: so far, no statistical differences in the scaling of avian energetics. Journal of Experimental Biology 205, 101–107.
| PubMed |
Schleucher, E. , and Withers, P. C. (2001). Re-evaluation of the allometry of wet thermal conductance for birds. Comparative Biochemistry and Physiology 129A, 821–827.
Swanson, D. L. (1991). Seasonal adjustments in metabolism and insulation in the dark-eyed junco. Condor 93, 538–556.
Vézina, F. , and Williams, T. D. (2002). Metabolic costs of egg production in the European starling (Sturnus vulgaris). Physiological and Biochemical Zoology 75, 377–385.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Woinarski, J. C. Z. (1985). Breeding biology and life history of small insectivorous birds in Australian forests: response to a stable environment? Proceedings of the Ecological Society of Australia 14, 159–168.
Woinarski, J. C. Z. , and Cullen, J. M. (1984). Distribution of invertebrates on foliage in forests of south-eastern Australia. Australian Journal of Ecology 9, 207–232.