Why I study roadkill
FLYBLOWN, MAGGOT infested, with limbs falling apart – you’d be forgiven for getting that retching feeling in your stomach at the sight of roadkill and carrion.
But for scientist Emma Spencer, death and decay aren’t such an aversion. Rather, it’s been her passion for many years.
“Ever since I can remember, I’ve been wandering around the bush investigating animal bones,” Emma says.
“Whenever I spotted a skull, femur or vertebrae, I’d pick it up and mull over endless questions such as: what animal did this bone belong to? How did it die? And how long has the bone been sitting there?
Now, as a PhD student at the Global Ecology Lab at the University of Sydney, Emma gets to ask these questions in a professional setting.
For the past three years, she’s been monitoring carrion across three different locations: the Blue Mountains, Kosciuszko National Park and the Simpson Desert in western Queensland.
Emma wants to know the role that carrion plays within Australian ecosystems, who it nourishes and what it attracts. But she’s also interested in the potential impacts that carrion may have on vulnerable animal species.
— Emma Spencer (@EE_Spencer) February 7, 2019
“Many animals that feed on carcasses also hunt for prey,” she says. “[And] animals may face an increased risk of being caught and eaten if they find themselves in close proximity to a carcass.
“On the other hand, carcasses could also provide a little bit of protection to these animals by redirecting potential predators to an alternative food source, by focusing predator attention away from certain areas, or by attracting certain predators that scare off or attack smaller predators that pose a greater environmental threat.”
Emma began by sourcing animal carcasses from the side of the road and from farmers who were conducting animal management culls.
The carcasses were then positioned across the three different studies sites and wildlife cameras were programmed to photograph anything and everything that approached.
At the Simpson Desert site, Emma also positioned artificial bird nests to test whether carcasses had a negative impact upon nesting success for ground-nesting birds, such as the critically endangered night parrot.
Conservationists working at Ethabuka, a conservation property managed by Bush Heritage Australia, are eager to find new ways to protect the elusive bird, and so Emma’s studies were greatly appealing.
“There’s a growing body of research suggesting that the reduction or increase of dingo populations is linked to the release of pressure on or suppression of cats and foxes.
“If dingoes kill or exclude these animals, then increasing their numbers via the provision of food such as carrion might offer some protection to the smaller animals that feral cats and foxes eat.”
While Emma is yet to prove that the carcasses could be used to protect vulnerable desert birds, her observations nonetheless revealed the various ways in which carcasses are harnessed by different animals.
Over the three years, more than 15 species were recorded feeding on the carcass meat or the insects living in the carcass meat.
But the carcasses weren’t just used as a source of food. Emma also observed that birds were collecting tufts of remaining hair from the remains to build their nests.
Here's an example of what a kangaroo tail can look like after a couple of birds have removed all the fur for nesting material. Without fail, every July/August I spot carcasses missing fur just like this and I know that breeding season is here! pic.twitter.com/NMaypsuMUO
— Emma Spencer (@EE_Spencer) July 30, 2019
The birds were also seen digging for maggots that had migrated away from a camel carcass after they’d finished feeding, ready to bury themselves in the ground to begin the transition from larvae into fly.
Despite the important information the study of carrion yields, the topic is the focus of very little research in Australia, according to Emma.
“The majority of work investigating carrion ecology occurs in Europe and North America, and much of this work has been centred on vultures.
“In many parts of the world vultures are declining – so it makes sense that so many people want to study them. Effectively, vultures feed solely on the remains of dead animals.”
Australia doesn’t have any animals such as vultures that feed exclusively on carrion, however, Emma feels that our lack of study in this area goes deeper.
“Worldwide, carrion research has been slow to develop. Probably because most people experience a general aversion to death.”
When Emma tells people about her research she gets mixed reactions.
“There are a few who turn green when I start talking about maggots and the process of putrefaction. But in general, most people react with genuine interest.
“While death is a subject that we consider every now and then, so few of us think about what happens to the physical body after life ends.
“Most are also unaware of how many creatures thrive upon animal remains and the important role that carcasses and death play in the movement of nutrients through systems, or, as The Lion King puts it, in the ‘circle of life’.”
Emma predicts that she’ll finish her PhD by 2020, but says her work on carrion at the Global Ecology Lab is just a taste of what’s to come.
There are currently projects focusing on mass mortality events that produce large amounts of carcasses, such as the fish die-offs in the Murray-Darling, as well as studies that look at using carcasses as methods to monitor ecosystem health.
“It is important that we learn more about how carcasses influence ecosystems in Australia,” Emma says.
“We produce so many carcasses on our roads, but also as part of our management practices.
“Because so many of our carnivorous animals are introduced and impact our systems in various ways, it is also important that we study the scavenging role that these animals have, especially in contrast to any native animals that feed from carcasses.”
~Tweet me your carcass pics (or any interesting carcass-related observations you have made)~ Whether you're on the road, walking to work or in the field and whether you're a scientist, farmer or hairdresser, I want to hear about all of the carrion you are seeing! #circleoflife pic.twitter.com/6Vasiy6y9i
— Emma Spencer (@EE_Spencer) March 11, 2019