Variability in the breeding season of Black Swans Cygnus atratus in southeast Queensland, Australia

Main Article Content

Lucy A. Coleman
Jonathan T. Coleman

Abstract

Variability in the duration of the breeding season and the mean number of annual breeding attempts recorded for Black Swans Cygnus atratus in southeast Queensland, Australia, were evaluated in relation to environmental variables. There was a significant correlation between the extent of the breeding season (measured as the number of months in which eggs were hatched) with both the number of breeding attempts made by paired birds in that year and also the number of territorial pairs recorded. This may reflect changes in the timing of breeding by individual pairs to reduce competition for favoured breeding and foraging locations. The number of breeding attempts per territorial pair in any one year was influenced primarily by summer rainfall and the Southern Oscillation Index (SOI), with higher values for both of these environmental variables being associated with more breeding attempts and increasing numbers of breeding pairs. We therefore suggest that the increasing numbers of breeding pairs, and also the increasing numbers of breeding attempts associated with more favourable weather conditions, may have led to the longer breeding seasons recorded for Black Swans in southeast Queensland in recent years.

Article Details

How to Cite
Coleman, L. A., & Coleman, J. T. (2024). Variability in the breeding season of Black Swans Cygnus atratus in southeast Queensland, Australia. Wildfowl, 252–265. Retrieved from https://tidsskrift.dk/Wildfowl/article/view/156350
Section
Standard Papers

References

Banks, A.N., Wright, L.J., Maclean, I.M.D., Hann, C. & Redfisch, M.M. 2008. Review of the Status of Introduced Non-native Waterbird Species in the Area of the African-Eurasian Waterbird Agreement: 2007 Update. BTO Research Report No. 489. British Trust for Ornithology, Thetford, UK.

Braithwaite, L.W. 1982. Ecological studies of the Black Swan. The timing and success of breeding on two nearby lakes on the Southern Tablelands of New South Wales. Australian Wildlife Research 9: 261–275.

Braithwaite L.W. & Frith H.J. 1969. Waterfowl in an inland swamp in New South Wales. 1. Habitat. CSIRO Wildlife Research 14: 1–16.

Briggs, S.V. 1992. Movement patterns and breeding characteristics of arid zone ducks. Corella 16: 15–22.

Bureau of Meteorology (BOM). 2024. Climate Statistics for Australian Locations. Brisbane Aero. Australian Government Bureau of Meteorology, Melbourne, Australia. Available at http://www. bom.gov.au/climate/averages/tables/cw_ 040842_All.shtml (last accessed 31/08/2024).

Cleveland, R.B., Cleveland, W.S., McRae, J.E. & Terpenning, I. 1990. STL: a seasonal-trend decomposition procedure based on loess. Journal of Official Statistics 6: 3–73.

Coleman, J.T. 2010. Observations on breeding in the Black Swan Cygnus atratus in south-eastern Queensland. Corella 34: 103–106.

Coleman J.T. 2014. Breeding biology of the Black Swan Cygnus atratus in south-east Queensland, Australia. Wildfowl 64: 217–230.

Coleman, J.T., Braithwaite, D.S. & Coleman L.A. 2021. Sexual size dimorphism in the black swan and an alternative to cloacal sexing. Corella 45: 1–6.

Dalby, L., McGill, B.J., Fox, A.D. & Svenning, J.C. 2014. Seasonality drives global-scale diversity patterns in Anatidae (Anseriformes) via temporal niche exploitation. Global Ecology and Biogeography 23: 550–562.

Duursma, D.E., Gallagher, R.V. & Griffith, S.C. 2018. Effects of El Niño Southern Oscillation on avian breeding phenology. Diversity & Distributions 24: 1061–1071.

Gibbs, H., Chambers, L.E. & Bennett, A.F. 2011. Temporal and spatial variability of breeding in Australian birds and the potential implications of climate change. Emu 111: 283–291.

Halse, S.A. & Jaensch, R.P. 1989. Breeding seasons of waterbirds in south-western Australia – the importance of rainfall. Emu 89: 232–249.

Grolemund, G. & Wickham, H. 2011. Dates and times made easy with lubridate. Journal of Statistical Software 40: 1–25.

Kingsford, R.T. & Norman, F.I. 2002. Australian waterbirds – products of the continent’s ecology. Emu 102: 47–69.

Kingsford, R.T., Curtin, A.L. & Porter, J. 1999. Water flows on Cooper Creek in arid Australia determine ‘boom’ and ‘bust’ periods for waterbirds. Biological Conservation 88: 231–248.

Kingsford, R.T., Jenkins, K.M. & Porter, J.L. 2004. Imposed hydrological stability on lakes in arid Australia and effects on waterbirds. Ecology 85: 2478–2492.

Marchant, S. & Higgins, P.J. (eds.). 1990. Handbook of Australian, New Zealand and Antarctic Birds, Vol. 1B. Oxford University Press, Melbourne, Australia.

Murton, R.K. & Kear, J. 1978. Photoperiodism in waterfowl: phasing of breeding cycles and zoogeography. Journal of Zoology 186: 243–283.

Norman F.I. & Nicholls N. 1991. The Southern Oscillation and variations in waterfowl abundance in southeastern Australia. Australian Journal of Ecology 16: 485–490.

R Core Team 2023. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria.

Serventy D.L. & Marshall A.J. 1957. Breeding periodicity in western Australian birds: with an account of unseasonal nestings in 1953 and 1955. Emu 57: 99–126.

Vilina, Y.A., Cofré, H.L., Silva-García, C., García, M.D. & Pérez-Friedenthal, C. 2002. Effects of El Niño on abundance and breeding of Black-necked Swans on El Yali Wetland in Chile. Waterbirds 25 (Special Publication 1): 123–127.

Wickham. H. 2016. ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag, New York, USA.

Williams M.J. 1981. The demography of New Zealand’s Cygnus atratus population. In G.V.T. Matthews & M. Smart (eds.), Proceedings of the Second International Swan Symposium, Sapporo, Japan, pp. 147–161. International Waterfowl Research Bureau, Slimbridge, UK.