Black swan Cygnus atratus

The behavioural ecology of black swans has been a long-term interest for the Mulder lab. Black swans are large, socially monogamous birds resident in wetlands across most of Australia. In 2006, we began tagging and monitoring the population at Albert Park, Melbourne. Individuals are marked with collars with unique identification codes allowing us to track individuals over time. This long-term monitoring program utilises a group of citizen scientists who regularly submit sightings of individual birds at various locations around Victoria, through a website (myswan.org.au) and a smartphone application (available from iTunes). Over time, many projects have been carried out on this population including research into mating systems, communication, and response to disturbance.

When we studied the breeding ecology of black swans, we discovered unexpectedly high levels of extra-pair paternity (EPP). EPP in swans does not appear to be related to ecological factors or genetic factors, nor does it appear to lead to greater variance in reproductive success of males. Another study was based around examining the function of the curled feathers that both sexes grown on their wings and display prominently in a range of social interactions. We found that individuals pair assortively with respect to curled feathers, suggesting the feathers may be involved in mutual sexual selection. Following on from this study, we found that brood sex ratio was not related to the degree of ornamentation (curly feathers) in either parent or to EPP. This suggests that parental attractiveness may be largely non-heritable.

In a study relating to other forms of communication, we examined the function of triumph ceremonies. Paired black swans regularly perform triumph ceremonies, most of which were initiated by the male. We found that the presence of dependent cygnets did not affect the frequency of ceremonies; however feeding experiments showed ceremonies increased when many swans were in close proximity. Pairs also performed triumph ceremonies in response to the playback of a triumph ceremony by another pair, but not in response to playback of an advertisement call by an unpaired black swan.

Our most recent study involved examining the response of black swans to the Australian Formula One Grand Prix. We measured population size, behaviour and stress hormone levels before, during and after this intense noise event. While we didn’t find any change in population size or behaviour, we did find evidence of a modest physiological response. Our results suggest that even intensely noisy and apparently disruptive events may have relatively low measurable short-term impact on population numbers, behaviour or physiology in urban populations with apparently high tolerance to anthropogenic disturbance. Nevertheless, the potential long-term impact of such disturbance on reproductive success, individual fitness and population health need to be carefully considered.

Information about our current black swan projects is available on the Research page.

Researcher profile:
Much of this research into the behavioural ecology of black swans was conducted by Dr. Ken Kraaijeveld as part of his PhD entitled “Mutual ornamentation and the behavioural ecology of black swans”. Ken is now a lecturer in Bioinformatics at the University of Applied Sciences, Leiden, Netherlands.

More information about this research can be found in these publications:

Payne, CJ, Jessop, TJ, Guay, P-J, Johnstone, M, Feore, M & Mulder, RA (2012). Population, behavioural and physiological responses of an urban population of black swans to an intense noise event. PLoS ONE 7: e45014. Full text

Mulder, RA, Guay, P-J, Wilson, M & Coulson, G (2010). Citizen science: recruiting residents for studies of tagged urban wildlife. Wildlife Research 37: 440-446. Full text

Patel, R, Mulder, RA & Cardoso, G (2010). What makes vocalization frequency an unreliable signal of body size in birds? A study on black swans. Ethology 116: 554-563. Full text

Guay, P-J & Mulder, RA (2009). Do neck collars affect the behaviour and condition of Black Swans (Cygnus atratus)? Emu 109: 248-251. Full text

Kraaijeveld, K, Ming, M, Komdeur, J & Mulder, RA (2007). Offspring sex ratios in relation to mutual ornamentation and extra-pair paternity in the black swan Cygnus atratus. Ibis 149: 79-85. Full text

Kraaijeveld, K, Carew, PJ, Billing, TM, Adcock, GJ & Mulder, RA (2004). Extra-pair paternity does not result in differential sexual selection in the mutually ornamented black swan (Cygnus atratus). Molecular Ecology 13: 1625-1633. Full text

Kraaijeveld, K, Gregurke, J, Hall, C, Komdeur, J & Mulder, RA (2004). Mutual ornamentation, sexual selection and social dominance in the Black Swan. Behavioral Ecology 15: 380-389. Full text

Carew, PJ, Adcock, GJ & Mulder RA (2003). Microsatellite loci for paternity assessment in the black swan (Cygnus atratus: Aves). Molecular Ecology Notes 3:1-3. Full text

Kraaijeveld, K & Mulder, RA (2003). Musk Duck brood parasitism on Black Swans. Wildfowl 53: 127-135.

Kraaijeveld, K & Mulder, RA (2002). The function of triumph ceremonies in the black swan. Behaviour 139: 45-54. Full text