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Swan sex study ruffles feathers |
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Next please: Albert Park swans 'queue' while Raoul measures their bills
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The research team prepares to measure a swan and attach a leg tag and microchip
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Flick through any gossip magazine and our obsession with extra-marital scandal is revealed - think Nick and Jessica, or Shane and Simone. But pop stars and sporting celebs aren't the only ones with wandering eyes. Research by a young Melbourne scientist is set to ruffle a few feathers as Dr Raoul Mulder exposes the infidelity of black swans.
"Swans have long been renowned as symbols of lifelong fidelity and devotion," said Raoul. "But our recent work has shown that infidelity is rife among black swans."
Raoul and his colleagues tagged and monitored more than 800 swans at Lake Wendouree in Ballarat, Victoria back in 1999. They discovered that one out of six young cygnets raised by a pair of swans was illegitimate; a high rate for a species honoured for their apparent monogamy.
So in May this year, Raoul set out to find out more about the black swan's raunchy relationships, working at a new site in Melbourne's inner east, Albert Park Lake.
"We want to understand why the birds are sometimes unfaithful to their partners and what tactics are used by males and females to influence the outcome of paternity," said Raoul.
With the mating habits of swans as secretive as the dancing doona antics on Big Brother, Raoul had to design some high-tech gadgets to complete his research.
"Each of the males at Albert Park has had a tiny microchip attached to one of its tail feathers," he explained. "The microchips are identical to those implanted in domestic pets for their identification, but their purpose in this study was to record the mating behaviour of the birds."
Selected female swans have been fitted with a miniature decoder unit that looks like a small backpack and is usually undetectable beneath the swan's folded wings. When a male and female swan mate, the female's decoder unit detects the microchip implanted in the male's feathers. The male's identity is registered, along with the time of copulation.
"A complete record of her mating behaviour over several weeks can be downloaded onto a computer when the swan is later recaptured," explained Raoul. "This information can then be related to the outcome of paternity of the cygnets, which we determine using DNA markers."
Early results from the study are intriguing. One decoder pack retrieved from a female confirmed that she mated not only with her own mate, but also an 'extra-marital' male. The copulation took place just before midnight. If this turns out to be a general pattern, it may explain why researchers haven't previously been able to catch the birds in the act - the matings take place under cover of darkness.
Such findings indicate the potential of the system to cast new light on swans' mating behaviour. But deploying the units hasn't all been plain sailing. Of the 250 swans on Albert Lake during the peak season, only half eventually bred. This severely limited Raoul's selection of swans.
"We were hesitant to attach decoders to birds we knew nothing about, so we focused on the individual birds we already knew to be in well established pairs. These swans began breeding in June - much earlier than usual - so we were also limited in by the number of birds who had not started breeding."
As the end of breeding season approaches, Raoul and his team are beginning to retrieve the decoder units from the female swans. But the task is not as easy as you might think! Some units have fallen into the lake as the birds begin to lose their feathers in spring. Others have been lost as birds disappear from the lake altogether. The units contain radiotracking devices, but with a range of just a few kilometres, there seems little hope of finding them.
Paternity testing of the cygnets will begin early next year, but Raoul is already speculating that the birds' adultery may have to do more with genetic compatibility between males and females, rather than being a case of certain males being attractive to all females.
"Our previous DNA analyses have shown that there is no one male that is sought out by all of the females," he said. "So there is not necessarily one attribute that is attractive to all of the female swans. We might find that the females copulate with males that have the desired attributes that their social partner is missing."
With all the affairs that Raoul's research uncovers, Albert Park Lake is set to become as scandalous as any day-time soapie. Like sands through the hour glass, these are the swans of our lake.
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Male and female black swans pair for life and take turns at protecting their eggs during mating season. Other birds who share parental duties include kookaburras, penguins and owls |
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Scientists believe that 90 per cent of bird species are socially monogamous. This means that couples share parental duties even when the male bird is not the biological father |
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Birds such as lyrebirds and bowerbirds are considered to be the most promiscuous, dedicating all their time to looking flashy and mating with as many females as possible |
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This isn't the first time swan's squeaky clean reputation has been questioned. In Greek mythology, Leda bore four children, but only two were to her husband Tyndareus, King of Sparta. Her other two children were fathered by the powerful God, Zeus, who seduced Leda by taking the form of a swan. |
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