Julia Ryeland is determined to unlock the breeding habits of the emu, a species that is poorly-studied for several good reasons.
Ethograms is a monthly column published in collaboration with the Australasian Society for the Study of Animal Behaviour (ASSAB), showcasing the work of early-career researchers. Andrew Katsis is a PhD candidate at Deakin University, and an outreach officer for ASSAB.
When ornithologist John Latham first described the emu in 1790, he named it Dromaius novaehollandiae: the ‘fast-footed New Hollander.’ This was an apt description; when escaping predators, emus can run as fast as 48km/hr over short distances. This, among other things, makes them rather difficult to research. In the 1960s, when CSIRO scientist Stephen Davies conducted one of the few detailed studies of wild emus, he reportedly captured birds by lassoing them from a fast-moving Land Rover.
Since then, most of our knowledge has come from captive emus — particularly during the emu farming boom of the 1990s, when the species was widely farmed for oil, meat and leather. Not surprisingly, most of this research focussed on productivity and breeding success in the farm environment.
“In terms of what they do in the wild, we don’t really know,” says Julia Ryeland, a PhD candidate at Western Sydney University’s Hawkesbury Institute for the Environment. “There’s not much that has been done at all: a couple of observational behavioural studies, but not much considering they’re on our coat of arms".
To fill the gaps in our emu knowledge, Ryeland has begun to explore the species' unorthodox mating system. Emus are socially monogamous — they form tight breeding pairs for most of the year — but, unusually among birds, all parental care falls to the male. Once the female lays her eggs, her partner will dutifully incubate them, eschewing all food and water for 56 days. "When he’s on the nest, he’s almost in a state of torpor,” says Ryeland. "His metabolic rate drops massively, because he’s not eating or moving”.
Shortly after laying her eggs, females will strike off in search of additional males. “We know that when he starts incubating, she’ll start vocalising for another mate quite loudly,” says Ryeland. “And so she’ll gain a second, and a third, and a fourth male, laying eggs in each of his nests".
For males, parental care is a massive commitment — not only is the incubation period physically taxing, but juveniles will accompany their fathers for up to 18 months, taking up two successive breeding seasons. It’s surprising, then, that males will often unknowingly raise offspring that are not their own: both female infidelity and brood parasitism are common.
To help understand how extra-pair mating affects population viability, Ryeland aims to collect paternity data in both captive and wild settings. But studying breeding in the wild is notoriously tricky. Ryeland has already struck out several times in search of wild emus, with limited success. Although considered quite abundant across the mainland, with an estimated population of around 700,000 birds, emus can be surprisingly cryptic.
Even once you have located an emu, capturing such a large animal takes some careful deliberation. In a farm environment, several people are required. “You essentially just walk up behind them and have three or four people press down on them and get them into the sitting position,” says Ryeland.
In the wild, this becomes even more problematic. The gung-ho 1960s approach with a Land Rover has fallen out of favour, as the stress of capture is potentially fatal to the birds. Instead, Ryeland plans to tranquilise and then anaesthetise her emus, before attaching VHF trackers that will allow her to track their movements over time. This year, she will practise this technique on a free-ranging captive population, before progressing to fully wild emus in 2018.
Ryeland hasn't always been a bird enthusiast: Her previous research project studied defence mechanisms in a colourful alpine insect, the mountain katydid. Even so, she quickly grew fond of the emu and its peculiarities. “They’re incredibly curious – I think that’s what I like the most," she says. "They have some really bizarre behaviours that I have no idea what they’re about — they do this strange dance where they flick their legs out and they look like they’re having a little bit of a seizure”.
Ryeland hopes that her behavioural findings will be used to inform management and conservation of the species. Sadly, emus and humans already have a chequered history. Three distinct varieties of emu — on Tasmania, King Island and Kangaroo Island, respectively — were driven to extinction by early European settlers. Likewise, the mainland species was persecuted as an agricultural pest in the early- to mid-20th century, surviving decades of hunting bounties and even an ill-fated military campaign called the Great Emu War.
Today, despite their overall abundance, emus are very susceptible to urbanisation, and occur less in the developed regions along Australia’s east coast. In the Northern Territory, too, the emu is considerable Vulnerable. It is “one of those species we’ll have to look out for in the future to see what happens to their conservation status,” says Ryeland.
Emus, when they can be found, are one of Australia’s most distinctive species, and are certainly deserving of more scientific attention. Unlike their playmate on the coat of arms, the kangaroo, we know precious little about the private life of our largest bird. Piecing together their breeding habits will be hard work, but Ryeland’s curiosity is equal to that of the birds she studies.