UPDATE: Project OzScav in the Blue Mountains (Jan ’18)

Over the past two years I’ve spent nearly 8 months in the field, monitoring rotting animal carcasses through the heat of the Simpson Desert, the cold of Kosciuszko and, in the Blue Mountains, through some of the most amazing thunder storms I’ve ever had the privilege to experience. I’ve managed to bog (and free) my vehicle in every study system, I’ve navigated swarms of wasps and angry feral pigs, howled with dingos and shared time with some incredible, hard-working volunteers. Now, with the fieldwork side of things slowly coming to a close, I feel as though I finally have a bit of time to sit down and write-up a few of those experiences, as well as some of the observations that I made whilst out in the field.

For this first post, I’ll go back to where it begun, to the Wolgan Valley in the Blue Mountains, and the summer of last year.

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Summer in the Wolgan Valley, in the Blue Mountains

Wolgan Valley, Blue Mountains – the second field trip (January, 2018)

 

I completed my first field season in the Wolgan Valley in August of 2017. Visiting the decaying carcasses each week, I was amazed by how long it took for them to disappear. In these cooler months, where frosts regularly coat the valley floor in white, animal remains were lasting for up to 12 weeks if not visited regularly by wild dogs, foxes or wedge-tailed eagles. Insect activity was also low and many of the carcasses drying out in the sun smelled almost pleasant, like spiced beef jerky.

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A wild dog examining the remains of an animal carcass

This second field trip would take place at around the hottest time of the year, and I was very interested to see how the carcasses and the visiting scavengers would differ from the winter season. I imagined that the insects would be far more active, but didn’t know how the wild dogs and eagles would respond to the heat.

I did quickly realise, however, that us humans wouldn’t fare so well. The process of lifting heavy animal carcasses over and under logs (getting them into position so that they could be monitored by our remote cameras) was hard work in the summer heat. I had 3 volunteers to help, but some of the carcasses weighed more than 40 kg and although fresh, gases were already starting to build, carrying with them the rancid smell of rotting flesh.

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Yellow grasses, Wolgan Valley in a summer drought

Most of my volunteers were less than pleased by the smell but the flies seemed to enjoy it, buzzing happily around us, tiny engines wurring in our ears. I noticed that they were already laying eggs in amongst the fur of the dead animals and it wouldn’t be long before a million tiny maggot mouths would start to work their magic.

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Maggots, working their magic on an animal carcass

When we were about halfway through the carcasses we took a sharp rock to the side of our front right tire and ended up with a flat. Not usually a huge problem, as long as you have a spare, right? Well, with the flies buzzing like crazy and the full heat of the day blaring down upon us, we soon discovered that although we had not one, but two spares, both of them were flat.

Bad luck, but also very poor planning on my behalf. It was the first of many important (and perhaps obvious) lessons that I was to learn in the field – always check your spares, especially if the vehicle isn’t yours.

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Changing a flat tire with another flat tire

Thankfully, although a good hour from town, we were lucky enough to have the support of a local mechanic. We managed to not only source a spare vehicle, but the mechanic was also able to provide a temporary fix for one of our tires.

While our vehicle situation was now much improved, we found ourselves restarting work late in the afternoon. We were all tired, but the carcasses couldn’t wait for a good night’s sleep. By the time we were done it was nearly midnight, and we were all in need of a shower.

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Setting up a remote cameras on a monitoring site

Once the carcasses were all positioned, we could take a breath (and have a shower). From this point on, it was all about monitoring the progress of decay, and taking note of the scavengers visiting each carcass site.

As anticipated, the insects went to town on the carcasses, the maggot mass peaked at 2-4 days after the carcasses were positioned and most of the meat was completely consumed in under a week. Various beetles and ants were also common, with some carcasses entirely covered by purple and black meat ants (Iridomyrmex purpureus). Most of these ants visited the carcasses to consume the many hundreds of maggots within. Although once the maggots had “migrated” away to begin the transformation from larvae to flies, the ants did switch to meat. You could hear them from quite a distance, chewing away at the drying flesh.

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Meat ants “attacking” the meat of an animal carcass

Aside from the insects, lace monitors (Varanus varius) could also be observed munching at the animal remains. Even when they weren’t present, I learnt to distinguish traces of their feeding. They would “bury” into the stomach area of dead animals, leaving behind a slight burrow and disturbing leaf litter and vegetation surrounding.

These creatures didn’t seem too perturbed by my presence and so I would often sit quietly and watch them eat.

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Lace monitor visiting a carcass site

In Australia, lace monitors are well known scavengers, but across the rest of the planet reptiles are rarely sighted at animal remains. Consequently, there seems to be an underappreciation of the role that some animals, particularly reptiles, might have in contributing to important ecosystem processes like carcass removal.

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Four lace monitors compete over an animal carcass

Mammals and birds were still major players in the process of carcasses decay during this season, although much less so than in the winter time when insect activity was low. My remote cameras tracked a huge number of dogs visiting some carcasses and while the insects might have contributed to most of the meat-removal, these larger animals aided in the spread of bones, and therefore nutrients, across the landscape.

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A large pack of wild dogs in the Wolgan Valley

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All that remains of a carcass set in summer, not a bone in sight

Many thanks to my volunteers Juri, Greg, Gill, Tash, Sierra and my wonderful supervisor Tom for helping out during this field season.

Next time…  a March field trip to Kosciuszko National Park.

 

 

Introducing Project OZScav

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Background

Carrion is a nutrient- and energy-rich resource that is used by a variety of organisms, particularly carnivorous vertebrates, arthropods and microbes. It can influence the movements and spatial distribution of scavenging species and, as many scavengers are also predators, the presence of carrion may have cascading effects on live prey.

The degradation of a carcass further influences soil properties, as well as the growth of certain plant species in the vicinity of the resource. Thus, carrion has the potential to affect many aspects of community ecology, and to play key roles in nutrient cycling and in shaping food-web dynamics through both direct and indirect pathways.

But despite the potential community-wide impacts of this resource, carrion ecology remains understudied, and research on the topic is primarily northern hemisphere based.

A new project to fill the knowledge gaps

Project OzScav’s main directive is to investigate the role of carrion in ecological communities in Australia.

Specifically, this project:

(1) explores how carrion is used by Australian vertebrates, arthropods and microbes,

(2) determines whether the presence of carrion has cascading impacts on surrounding live prey, and

(3) examines the effects of carrion on soil nutrients and subsequent plant growth surrounding the resource.

The project currently spans three study systems across Australia, representing temperate, subalpine and desert biomes.

Our main funding and project partners include , , , , , NSW National Parks, and Australia and Pacific Science Foundation.

Data are providing insight into the role of carrion in Australian food-webs, and, as study locations are situated on National parkland and conservation reserves, data are also contributing directly to local land management (e.g. by informing land managers of the potential impacts of carcasses left to lie in the environment following culling events).

Project updates as well as student and volunteer opportunities will be posted on this website, via my own twitter account (@EE_Spencer) and via the twitter account of Dr Thomas Newsome who is the lead researcher on the project (@NewsomeTM).

Feel free to get in contact if you have any questions!

Project OZscav hits the Big Red: a successful first field season at Ethabuka, in the Simpson Desert

This field trip served as the debut to major carrion ecology research in the Simpson Desert. It also began the first field season of the NESP (TSR Hub) funded project investigating the potential impacts of carrion on ground nesting birds such as the night parrot (Pezoporus occidentalis), in Australian arid environments. Built as a collaboration between the University of Sydney, the University of Queensland and Bush Herritage Australia (BHA), this study is broader than just carrion, predators and prey; it also explores the use of carrion by insects, and will develop understanding on the flow-on impacts of this resource to surrounding soil and plant communities.

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Volunteer Gill and his photoshoot with a potential carrion scavenger, the brown falcon (Falco berigora; Photo credit: Emma Spencer)

Overall, the first field season went very well, with 20 carcass sites established. At each of these sites, plant surveys were conducted and soil samples collected to provide baseline “before carrion” data. Motion sensor cameras were positioned to monitor vertebrate scavenger and predator use of carcasses and insect pitfall traps were also dug into the ground to enable detection of ants, flies and beetles using the resource. In addition to the animal, soil and plant monitoring, artificial “fake” nests were constructed in the sand at various distances surrounding each carcass to determine whether proximity to carrion influences nest predation.

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Emma setting up a motion-sensor camera to monitor a carcass positioned on a sand dune crest (Photo credit: Thomas Newsome)

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Tom setting up a motion-sensor camera to monitor predation on an artificial “fake” nest (Photo credit: Emma Spencer)

While results are still incoming, and images, soil samples and insect traps are yet to be sorted, identified and analysed, the camera images have shown a great deal of activity on the carcasses thus far. Wedge-tailed eagles, ravens and red foxes are dominant on many carcasses and dingoes and feral cats are also making an appearance. Ravens and foxes have dominated nest predation and there appears to be a clear negative impact of the presence of carrion on nest predation.

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A motion-sensor camera image showing five wedge-tailed eagles (Aquila audax) feeding on a kangaroo carcass at Ethabuka

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A motion-sensor camera image showing a feral cat feeding on a carcass, under the watchful eye of a corvid

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A red fox captured by a motion-sensor camera removing an egg from a “fake” nest

This work will be repeated in September/October of this year (2018), with a few additions to the method. For example, further work involving the remains of camels may be incorporated and a camel carcass is currently being monitored on site as a “pilot” to this work. Indeed, reducing feral camel numbers via culling is a key management concern for BHA, but they are also determined to assess potential impacts of such consistent (and potentially broader-scale) culls on the surrounding environment.

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“Culled” camel carcass monitored by a remote camera at Ethabuka (Photo credit: Thomas Newsome)

 

Research update: Project OZscav wraps up its first field season in the Wolgan Valley  

Mid-October marks the end of the first season of fieldwork for Project AusCarcasscam in the Wolgan Valley. In total, over 300,000 pictures have been downloaded from remote-sensor cameras, and approximately 100 plant samples, 40 soil samples and 80 insect traps have been collected for further analysis.

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The Wolgan Valley study site, set on the north-western end of the Blue Mountains National Park. Photo credit: Thomas Newsome

Project AusCarcasscam is a study supported in part by the Emirates One&Only Wolgan Valley Resort, which investigates Australia’s scavenging community and the wider effects of carrion on the landscape. Scavengers feed on dead animal material, commonly referred to as carrion, or animal carcasses, and in Australia may include animals such as the dingo and feral dogs, red foxes, ravens, lace goannas and wedge-tailed eagles. Despite potentially being supplied with large quantities of meat from road kill, carcasses left by hunters, livestock that die in paddocks and wildlife culls, there have been few studies that examine scavenger communities in Australia and the effects of carrion resources in these environments.

In order to capture the diverse array of wildlife that makes use of carrion resources, we set up remote-sensor cameras on 20 kangaroo carcasses distributed across the Wolgan Valley. These cameras were programmed to capture pictures of all animals visiting the carcass sites and will help to develop an understanding of the scavengers present in the Valley. As some of these scavengers are also considered pests (in particular, feral dogs and red foxes), the research will also contribute to pest management programs run in the Valley and across Australia. For example, if this study finds that pest animals make frequent use of carrion resources, this might suggest a need to develop carrion disposal programs whereby animal carcasses are removed from the road side after vehicle collisions, and from farmlands following wildlife culls and livestock death.

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Setting up remote sensor cameras to document scavenging activity at carcass sites. Photo credit: Thomas Newsome

Carrion also attracts a much smaller kind of scavenger – flies, beetles and ants may also feed on animal carcasses. In order to gain a greater appreciation of insect scavenging activity, we also set up small “pitfall traps”, which were designed to capture insects feeding on the carcasses. In addition, soil and plant samples were collect on and around carcass sites to determine whether nutrient-rich carcasses enhance soils and contributes to plant growth. Together, these collections will add to a greater understanding of carrion and the myriad of affects it can have on the surrounding environment.

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Making note of plant diversity around a carcass site. Photo credit: Thomas Newsome

As this is the first of four study periods that will be conducted in the Wolgan Valley between 2017 and 2019, expect future updates on the progress of this project. Also watch out for news on carrion and scavenger work in different parts of Australia, as this study will soon be extended into the Simpson Desert, western Queensland, and into Kosciuszko National Park, south western New South Wales, where it will address pest management concerns and maybe even contribute to the conservation of rare Night Parrot populations!

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Two wedge-tailed eagles fight over the remains of an eastern grey kangaroo. Picture taken using a Reconyx motion sensor camera.

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A lace goanna moves in to feed on the remains of a dead kangaroo. Picture taken using a Reconyx motion sensor camera.

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A cheeky raven pulls at the tail feather of an unsuspecting wedge-tailed eagle. Picture taken using a Reconyx motion sensor camera.

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Two wild dogs feed at the remains of an eastern grey kangaroo. Picture taken using a Reconyx motion sensor camera.