Dingo dinners: what’s on the menu for Australia’s top predator?

Tim Doherty, Deakin University; Chris Dickman, University of Sydney; Dale Nimmo, Charles Sturt University; Euan Ritchie, Deakin University, and Thomas Newsome, University of Sydney

The dingo is Australia’s largest land-based predator, occurring across most of the mainland and on many nearshore islands.

Our new research, published in the journal Mammal Review, reveals the breadth and diversity of dingo diets across the continent.

We compiled and analysed 73 sets of data, containing details of more than 32,000 dingo droppings or stomach contents, to document the range of different species that dingoes eat, and how their diets vary between different environments.

A wide-ranging diet

We found that dingoes eat at least 229 vertebrate species. This includes 62 small mammals (less than 500 grams in mass), 79 medium-sized and larger mammals, 10 species of hoofed mammals, 50 birds and 26 reptiles. Dingoes also eat insects, crustaceans, centipedes, fish and frogs.

The true number of species is likely to be much higher because dingo diets have been poorly studied in many parts of Australia, such as Cape York Peninsula.

---

Read more:
Dingoes do bark: why most dingo facts you think you know are wrong

---

Large (at least 7kg) and medium-sized (0.5-6.9kg) mammals were the most common components of dingo diets, followed by small mammals, rabbits, arthropods, reptiles, birds and hoofed animals.

Average occurrence of eight food types in the diet of dingoes. Values represent the percentage of droppings/stomachs that contained each food type.

A range of introduced pest species also feature in dingo diets, including deer, goats, rabbits, hares, black rats, house mice, foxes and cats. In recent decades, the occurrence of sambar deer in dingo diets has increased as this invasive species has expanded its range.

Dingoes also eat sheep and cattle, although dietary samples are unable to distinguish between predation and scavenging, and hence tell us little about dingo impacts on livestock production. Dietary samples also do not reveal instances of dingoes killing livestock without eating them.

Regional variation

We found that what dingoes eat depends on where they live. For instance, in arid central Australia, birds, reptiles, rabbits, small mammals and insects form major parts of dingo diets. In contrast, these food groups are less important in temperate and subtropical eastern Australia, where medium-sized and large mammals such as kangaroos, bandicoots and possums are more important.

Frequency of different food groups in dingoes’ diet. Each circle represents a study and is scaled proportionally with dietary occurrence; larger circles represent a higher frequency of that food type. Top row: arthropods and small mammals (less than 500g); middle row: reptiles and medium-sized mammals (0.5-6.9kg); bottom row: rabbits and large mammals (at least 7kg).

The higher occurrence of medium-sized mammals in dingo diets in eastern Australia may be due to the lower extinction rates of native mammals there. In contrast, central Australia is a global mammal extinction hotspot, which probably accounts for the low occurrence of medium-sized mammals in dingo diets in arid and semi-arid areas.

Nonetheless, one medium-sized mammal was a major food item for dingoes in arid areas: the European rabbit. In some areas, more than 50% of dingo droppings or stomachs contained the remains of this invasive species. It is possible that native medium-sized mammals previously constituted a major part of dingo diets in arid Australia, but have since been replaced by rabbits.

Local prey availability plays a major role in determining what dingoes eat. For instance, in the Tanami Desert, reptiles were most common in dingo diets during warmer months when they are most active. However, very few studies have collected data on prey availability, partly because of the sheer number of different animals that dingoes eat.

Threatened species

Dingoes kill or eat at least 39 native species that are classed as threatened or near-threatened on the IUCN Red List. These include the northern quoll, golden bandicoot and bridled nailtail wallaby.

This tally is higher than the number of threatened species in feral cat diets (based on a previous study that used similar methods), even though cats eat almost twice as many different species overall as dingoes (400 and 229, respectively).

---

Read more:
Why the WA government is wrong to play identity politics with dingoes

---

Today’s threatened native species co-existed with dingoes for a long time before European colonisation, which means they were able to withstand dingo predation without going extinct.

But now a combination of small population sizes of some threatened species and exacerbating factors such as habitat loss, foxes and cats means some threatened species could be vulnerable to even low levels of dingo predation. Predation by dingoes should therefore be a key consideration when attempting to conserve or restore threatened species.

Dietary studies are one way we can understand how dingoes interact with other species. Our study also highlights that we still have much to learn about our native top predator. In many parts of Australia, the favourite foods of dingoes are still a mystery.

---

The authors acknowledge the contribution of Naomi Davis, Dave Forsyth, Mike Letnic, Russell Palmer, Joe Benshemesh, Glenn Edwards, Jenny Lawrence, Lindy Lumsden, Charlie Pascoe, Andy Sharp, Danielle Stokeld, Cecilia Myers, Georgeanna Story, Paul Story, Barbara Triggs, Mark Venosta and Mike Wysong to this research.

Tim Doherty, Research Fellow, Deakin University; Chris Dickman, Professor in Terrestrial Ecology, University of Sydney; Dale Nimmo, Associate professor/ARC DECRA fellow, Charles Sturt University; Euan Ritchie, Associate Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University, and Thomas Newsome, Lecturer, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisement

Caught on camera: The fossa, Madagascar’s elusive top predator

Fossa (Cryptoprocta ferox) at the Houston Zoo.
Josh Henderson, CC BY-SA

Asia Murphy, Pennsylvania State University

Mention wildlife on Madagascar and the first thing listeners probably picture is the island’s famed lemurs. As many people know, these unique primates are found nowhere else, and are the most endangered group of mammals in the world. But few people realize that lemurs’ fate is directly bound up with that of Madagascar’s largest predator, the fossa (Cryptoprocta ferox), which is threatened by some of the same pressures.

Fossa are terrier-sized, cat-like relatives of mongoose with tails as long as their bodies. Like other top predators such as lions and wolves, they play a critical ecological role regulating the populations of their prey.

Like much of Madagascar’s wildlife, fossa are found nowhere else in the world. But scientists know little else about them, including how many fossa there are. They are rare, difficult to see in the wild, and lack unique coat patterns that would make it easy to distinguish individual animals.

I worked on a team of researchers from the United States and Madagascar that spent seven years surveying Madagascar’s largest protected area – a zone the size of Connecticut – with trail cameras to see if we could determine how many fossa were there. We found that this area holds a significant portion of the global fossa population, and is likely the last stronghold for this unique species. Our research provides key information that can help correctly assess fossas’ threatened status and lay the basis for appropriate conservation action.

An alert fossa looks out over the rainforest.

Madagascar’s top carnivore

Fossa weigh about 20 pounds and can prey on most of Madagascar’s other species. They are capable hunters on land and in the trees, using their tails for balance and killing by biting through their prey’s skulls. One study found that fossa were largely responsible for two lemur family groups disappearing from forests over a two-year period. Fossa, like other top predators, help keep prey populations at a level that their habitat can support, and rid the population of diseased and weak individuals.

Fossa also exhibit some very interesting behaviors. They are one of nine mammalian species whose sexually immature females go through a period of transient masculinization. During this phase, their clitorises enlarge and grow spines to look like an adult male fossa’s penis. Researchers think this helps sexually immature females avoid the aggressive attentions of males looking for females with which to mate.

In the deciduous forests of western Madagascar, scientists have discovered that male and female fossa will gather together at the same spot year after year to mate. Otherwise, however, fossa were thought to be solitary until 2010, when researchers observed three male fossa working together to kill a lemur. Since then, some male fossa have been seen to team up with another male or two to hunt prey and protect a larger territory than solitary males. And in 2015, our study captured photos suggesting that male fossa in the eastern rainforests will also associate.

Two male fossa captured on camera in northeastern Madagascar.
Asia Murphy

Lack of funding and political instability has made it hard for Madagascar’s government and conservation organizations to study the fossa. Because of their elusive nature, it is particularly hard to figure out basic things, such as how many fossa there are in an area. And without good numbers, scientists can’t assess whether a species is threatened or develop plans for protecting it.

Tracking fossa with cameras

Automatic cameras, known as camera traps, are a standard tool for collecting information on elusive wildlife in remote areas. The only thing “trapped” is the animal’s digital image.

Our images showed what type of habitat fossa used, when they were active, and how they co-existed with other carnivores such as dogs. Variations among individual animals, such as scars, tail width and kinkiness, and the presence and number of ear nicks, made it possible to start picking out certain fossa from the population and “follow” them from one camera to another.

One of our top goals was assessing how many fossa were present in the reserve and how close together they were. Determining density is key for conserving species. Once we knew know how many fossa there were, on average, in a unit of area such as square kilometer, we could estimate how many there were in the entire region and compare between different protected areas.

Flat Tail, seen in 2008 as a young pup (left) and 2013 as a mature male (right). We were able to follow this fossa as he grew up thanks to his strange and unique tail tip.
Asia Murphy & Zach Farris

The value of a number

Over a seven-year period we ran 15 surveys across seven study sites in the reserve. For months on end, we set up cameras, checked them, downloaded data and then moved cameras to survey as much area as possible. In all of this time, I never personally saw a fossa, but two local field assistants saw fossa in the trees once or twice.

Next came three years of analyzing photos, recording which animals had identifying marks and how far those marked fossa moved during their daily activities. Finally, nearly a decade after the very first survey in Masoala-Makira, we had a population estimate.

We calculated the fossa population in Masoala-Makira at 1,061, give or take around 500 animals. This worked out to about 20 fossa per 100 square kilometers. In other words, we had a small town of lemur-eating carnivores living in an area the size of Connecticut.

Why is this important? Because our colleague Brian Gerber did a similar study in southeastern Madagascar, with one important difference: He applied his estimate to the area of all of Madagascar’s protected forests. He estimated there to be 8,626 fossa in the entire world.

Only two protected areas were large enough to hold enough fossa that the population could stay stable, at the very least, despite individuals dying or being killed. We showed that Masoala-Makira is one of them. And as the largest protected area in Madagascar, it will be home to fossa long after they disappear elsewhere due to hunting and habitat loss.

The next priority is to survey Madagascar’s other protected area large enough to hold a self-sustaining population, the Zahamena-Mantadia-Vohidrazana complex, to better estimate the global fossa population. And local governments need to attempt to curb hunting within protected areas and control feral dogs and cats, which can kill native species and spread diseases.

Rare and charismatic species typically get the most conservation attention, especially through events like National Geographic’s Big Cat Week. In fact, however, there are four times more lions than fossa in the entire world. Maybe it’s time for Fossa Friday.

Asia Murphy, PhD candidate, Pennsylvania State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Another attack on the Bureau, but top politicians have stopped listening to climate change denial

Michael J. I. Brown, Monash University

Has the Australian climate change debate changed? You could be forgiven for thinking the answer is no.

Just this week The Australian has run a series of articles attacking the Bureau of Meteorology’s weather observations. Meanwhile, the federal and Queensland governments continue to promote Adani’s planned coal mine, despite considerable environmental and economic obstacles. And Australia’s carbon dioxide emissions are rising again.

So far, so familiar. But something has changed.

Those at the top of Australian politics are no longer debating the existence of climate change and its causes. Instead, four years after the Coalition was first elected, the big political issues are rising power prices and the electricity market. What’s happening?

---

Read more: No, the Bureau of Meteorology is not fiddling its weather data.

---

A few years ago, rejection of climate science was part of the Australian political mainstream. In 2013, the then prime minister Tony Abbott repeated a common but flawed climate change denial argument:

Australia has had fires and floods since the beginning of time. We’ve had much bigger floods and fires than the ones we’ve recently experienced. You can hardly say they were the result of anthropic [sic] global warming.

Abbott’s statement dodges a key issue. While fires and floods have always occurred, climate change can still alter their frequency and severity. In 2013, government politicians and advisers, such as Dennis Jensen and Maurice Newman, weren’t shy about rejecting climate science either.

The atmosphere is different in 2017, and I’m not just talking about CO₂ levels. Tony Abbott is no longer prime minister, Dennis Jensen lost preselection and his seat, and Maurice Newman is no longer the prime minister’s business advisor.

Which Australian politician most vocally rejects climate science now? It isn’t the prime minister or members of the Coalition, but One Nation’s Malcolm Roberts. In Australia, open rejection of human-induced climate change has moved to the political fringe.

Roberts has declared climate change to be a “fraud” and a “scam”, and talked about climate records being “manipulated by NASA”. He is very much a conspiracy theorist on climate, as he is on other topics including banks, John F. Kennedy, and citizenship. His approach to evidence is frequently at odds with mainstream thought.

//platform.twitter.com/widgets.js

This conspiratorial approach to climate change is turning up elsewhere too. I was startled by the author list of the Institute of Public Affairs’ new climate change book. Tony Heller (better known in climate circles by the pseudonym Steven Goddard) doesn’t just believe climate change is a “fraud” and a “scam”, but has also promoted conspiracy theories about the Sandy Hook school massacre. This is a country mile from sober science and policy analysis.

So where is the Australian political mainstream? It’s not denying recent climate change and its causes, but instead is now debating the policy responses. This is exemplified by political arguments about the electricity market, power prices, and the Finkel Review.

---

Read more: What I learned from debating science with trolls

---

While this is progress, it’s not without serious problems. The debate may have rightly moved on to policy rather than science, but arguments for “clean coal” power are at odds with coal’s high CO₂ emissions and the failure thus far of carbon capture. Even power companies show little interest in new coal-fired power plants to replace those that have closed.

The closure of the Hazelwood power station was politically controversial.
Jeremy Buckingham/flickr

History repeating?

Have those who rejected global warming and its causes changed their tune? In general, no. They still imagine that scientists are up to no good. The Australian’s latest attacks on the Bureau of Meteorology (BoM) illustrate this, especially as they are markedly similar to accusations made in the same newspaper three years ago.

This week, the newspaper’s environment editor Graham Lloyd wrote that the BoM was “caught tampering” with temperature logs, on the basis of measurements of cold temperatures on two July nights at Goulburn and Thredbo. For these nights, discrepant temperatures were in public BoM databases due to automated weather stations that stopped reporting data. The data points were flagged for BoM staff to verify, but in the meantime an amateur meteorologist contacted Lloyd and the Institute of Public Affairs’ Jennifer Marohasy.

In 2014, Lloyd cast doubt on the BoM’s climate record by attacking the process of “homogenisation,” with a particular emphasis on data from weather stations in Rutherglen, Amberley and Bourke. Homogenisation is used to produce a continuous temperature record from measurements that may suffer from artificial discontinuities, such as in the case of weather stations that have been upgraded or moved from, say, a post office to an airport.

The Tuggeranong Automatic Weather Station.
Bidgee/Wikimedia Commons

Lloyd’s articles from this week and 2014 are beat-ups, for similar reasons. The BoM’s ACORN-SAT long-term temperature record is compiled using daily measurements from 112 weather stations. Even Lloyd acknowledges that those 112 stations don’t include Goulburn and Thredbo. While Rutherglen, Amberley and Bourke do contribute to ACORN-SAT, homogenisation of their data (and that of other weather stations) does little to change the warming trend measured across Australia. Australia has warmed over the past century, and The Australian’s campaigns won’t change that.

In 2014, the government responded to The Australian’s campaign by commissioning the Technical Advisory Forum, which has since reviewed ACORN-SAT and found it to be a “well-maintained dataset”. Prime Minister Abbott also considered a taskforce to investigate BoM, but was dissuaded by the then environment minister Greg Hunt.

How will Malcolm Turnbull’s government respond to The Australian’s retread of basically the same campaign? Perhaps that will be the acid test for whether the climate debate really has changed.

Michael J. I. Brown, Associate professor, Monash University

This article was originally published on The Conversation. Read the original article.

Thinking big gives top predators the competitive edge

Dingoes can help manage devastating red fox and feral cat numbers, but only if we let enough of them live in key areas.
Bobby Tamayo, Author provided

Thomas Newsome, Deakin University

Dingoes could be the key to controlling red foxes and other invasive predators, but only if we encourage them in large enough numbers over a wide enough area, our research shows.

Interest in re-introducing or restoring top predators, like dingoes and wolves, has been fuelled by recent studies demonstrating their important roles in their ecosystems. They can especially be vital in suppressing the abundance of lower-order competitors or “mesopredators”, like red foxes and possibly feral cats (which can have devastating effects on native species).

But researchers have found top predators aren’t always successful in reducing mesopredator numbers. Until now, such variation has been linked to human presence, land-use changes and environmental factors such as landscape productivity.

However, our research, published yesterday in Nature Communications, found that a key factor for success is high numbers of dingoes and wolves across their natural range.

The density effect

If you look at how species are typically distributed across a landscape – their range – ecological theory predicts there’ll be lower numbers at the outer edges of their range.

If you do need large numbers of top predators to effectively suppress mesopredators, the core of their range is potentially the best place to look.

We tested this idea, looking at the dingo in Australia and the grey wolf in North America and Europe. The mesopredators included the red fox in Australia, the coyote in North America and the golden jackal in Europe.

We looked at three regions in our study. Predator distribution is shown for: a) coyotes (hashed) and grey wolves (orange) in Saskatchewan, North America (present day); b) golden jackals (hashed) and grey wolves (orange) in Bulgaria and Serbia (present day); and c) red foxes (hashed) and dingoes (orange) in Queensland, Australia (in the 1950s).
Predator images: Doug McLaughlin; Bobby Tamayo, Harley Kingston/flickr, Larry Lamsa/flickr

We used information from bounty hunting programs, as these provide data on predator numbers across a wide geographical area. In the case of Australia we used historic data from the 1950s, as this is the most recent reliable information about red fox and dingo distribution. The actual population numbers of red foxes and dingoes have changed substantially since then, but the nature of their interactions – which is what we were investigating – has not.

We determined that top predators exist in higher numbers at the core of their ranges in comparison to the edges. We then looked at mesopredator numbers across the range edges of their respective top predator.

Predator bounties and top predator range edges in each continent. The number of bounties (representing the number of animals killed) are given for each hunting unit in North America (collated from 1982 to 2011) and Europe (collated from 2000 to 2009), whereas each square in Australia represents the number of bounties in a 100-by-100km area (collated from 1951 to 1952). Top predators are in a–c. Mesopredators are in d–f. Darker colours within each hunting unit indicate greater bounty return numbers and, by inference, a higher abundance for the respective predator. Dashed black lines indicate top predator range edges. Australia was divided into two sections for the analysis (east and west) as shown.

The results, which were consistent across the three continents, suggest that top predators can suppress mesopredators effectively (even completely) but only in the core of their geographic range, where their numbers are highest.

In other words, abundant top predators can exert disproportionate mesopredator control once their numbers increase past a certain point.

Example of the results from Australia (western side of Queensland). The blue lines indicate the abundance of each predator (note that the values on the y-axis are scaled so do not reflect actual numbers). The black dashed line indicates where there is a sharp change in predator abundance (the breakpoint). The red dashed lines indicate 95% confidence intervals (a measure of uncertainty) either side of the breakpoint. Distance values less than zero relate to areas outside the dingoes’ range, while distance values greater than zero relate to areas within the range. In summary, abundances of the red fox decline sharply as you move further into the range of the dingo.

The ‘enemy constraint hypothesis’

The relationship we uncovered is now formalised as the “Enemy Constraint Hypothesis”. It could apply to other predator dyads, where two animals compete for similar resources – even relationships involving parasites and pathogens.

Our findings are important for understanding species interactions and niches, as well as the ecological role of top predators. It could explain why other studies have found top predators have little influence on mesopredators: they were looking at the edge, not the core, of the top predators’ range.

This is a conceptual model of the Enemy Constraint Hypothesis. On the edge of a top predator’s range, mesopredator abundance should decline as top predator numbers increase. The breakpoint for the mesopredator indicates where their population nears zero. The breakpoint for the top predator indicates where their abundance starts to decline sharply on the edge of the range.

How many top predators do we need?

Dingoes can be vital for reducing red fox and possibly feral cat numbers. In our case studies the ranges of each top predator were limited primarily by human use of the land and intensive shooting, trapping and poisoning.

Killing pack animals like dingoes can fracture social groups, potentially altering their natural behaviour and interactions with other species. Future studies on predator interactions therefore need to consider the extent to which the animals are acting in response to human intervention.

If we want to benefit from the presence of top predators, we need to rethink our approach to management – especially where they are subjected to broad-scale control, as the dingo is in some parts of Australia.

Changing our relationship with top predators would not come without its challenges, but high extinction rates around the world (and especially in Australia) clearly indicate that we urgently need to change something. If this includes restoring top predators, then we need to think big.

Thomas Newsome, Fulbright Scholar and Postdoctoral Research Fellow, Deakin University

This article was originally published on The Conversation. Read the original article.

Check In: Day 2 of Holiday

I have had a most interesting couple of days on the road and in the bush. Currently I’m in a motel room at Woolgoolga, near Coffs Harbour on the mid-north coast of New South Wales, Australia. ‘Hardly the wild,’ I hear you say, and you’re quite right – it isn’t. The weather was beginning to change I noticed on the final leg of my day’s itinerary, so I decided to hide out in a motel room for the night – good decision, it’s pouring outside.

I won’t give all away – I’ll leave the main description of the holiday to the website – but just some of the ‘downlights’ of the first couple of days for this post.

I didn’t arrive at Cathedral Rock National Park until just on dark, but did get the tent up prior to darkness arriving – when it did, it was dark! The campfire took an eternity to get going as all of the timber was damp and by the time I got it started it was time for bed – all-be-it an early night (7.30pm). I had decided to not spend the money on replacing all of the gear I needed to replace for camping, following the loss of a lot of gear over the years due to storage, etc. I hadn’t done much in the way of bushwalking or camping for years due to injuries sustained in my car crash and a bad ankle injury, so I left it all a bit late. I figured that for this holiday I’d make do and replace the gear with quality gear before the next trip. In short, I’ll get by – but it would have been nice to have some good gear just the same. It was a very cold night let me tell you – and long.

When I reached the heights of my first walk today, standing on top of Cathedral Rock National Park, my digital camera decided to die on me. I knew there was something wrong with it during the ascent as it was really chugging away taking pictures. I did get a couple of reasonable panoramic shots on the top of Cathedral Rock before it died, so that was good. I took stills with the video camera I was using, so it wasn’t a complete loss. When I completed the Woolpack Rocks walk I made the trip to Coffs Harbour to seek a replacement and got one for a reasonable price. It’s just another compact and so I will also buy a digital SLR prior to my next trip I hope. My previous SLR was basically destroyed when the camera cap came off during a multiple day bushwalk and all manner of stuff got into it. It wasn’t digital so I didn’t bother repairing it.

So tomorrow – off to Dorrigo National Park I hope and several lengthy walks I haven’t done before. Hopefully the rain will clear.

 

Mount Everest to be Given a Clean Up

The world’s highest mountain, Mount Everest, is to be given a clean up. Everest, which was first climbed by Edmund Hillary in 1953, has become something of a garbage tip. Everything from climbers rubbish to dead bodies has been left on the mountain. Now a Nepalese expedition made up of twenty Sherpa mountaineers and eleven support crew is seeking to remove some of the garbage left behind since that first ascent.

The government of Nepal wants to clean up the popular tourist attraction, bringing down rubbish that includes old tents, climbing equipment and the odd body. Global warming has led to much of the rubbish (and several bodies) no longer being covered by snow and ice.

Over 300 people have been killed attempting the climb to the top of the world, the Mount Everest summit.

For more on this story, see the Reuters article at:

http://af.reuters.com/article/worldNews/idAFTRE63I0XE20100419