Photos from the field: Australia is full of lizards so I went bush to find out why



A lace monitor (Varanus varius)
Kristian Bell, Author provided

Kristian Bell, Deakin University

Environmental scientists see flora, fauna and phenomena the rest of us rarely do. In this new series, we’ve invited them to share their unique photos from the field.


Though it may not be as famous a stereotype as shrimps on the barbie, deadly snakes or Vegemite, Australia is renowned in certain scientific circles for being the “land of the lizards”.

Australia has a higher diversity of lizards than anywhere else in the world. The number of different species within a single part of remote, central Australia well exceeds similar desert environments, such as the Kalahari in Africa, or the US.

Over the last 50 years, scientists have tried to understand the cause of this extraordinary and unique diversity.

Some suggest unpredictable resources in the arid outback, such as sporadic rain, favour low-energy animals like lizards over birds and mammals. Others claim a high diversity of termites allows lots of different termite-eating lizards to co-exist.




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Or perhaps the presence of shrubs, sparse trees and grass clumps provide a variety of niches (microhabitats) for tree and litter dwelling species. Despite these many hypotheses, no consensus has ever been reached.

My research explores the role of spinifex, a spiky clumping grass that’s typically found in the arid outback, often in conjunction with lizard diversity hotspots.

With many species found nowhere else on earth, some Australian lizards are threatened with extinction. Understanding how and why lizards use this iconic outback plant can help us conserve them, by predicting how they might respond to disturbances such as habitat loss and climate change.




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Following many trips to the outback, I was surprised to find locals who had never encountered some of the species I was studying. Taking photographs of these often small and overlooked animals helps me to better engage the community and raise the wider public profile of lizards, compared to other, more “charismatic” native animals.

A thriving desert ecosystem

All 60 species of spinifex grasses (members of the Triodia genus) are found only in Australia. Although spinifex habitats cover more than one-fifth of mainland Australia, the plant is little-known and little-loved by non-naturalists.

Spinifex clumps on red dirt
A typical mallee ecosystem where we conduct our research, with plenty of spinifex clumps interspersed with the many-stemmed trunks, characteristic of mallee eucalypts.
Kristian Bell, Author provided

Spinifex typically forms a spiky and impenetrable clump that provides useful, and in some cases essential, resources to lizards, birds, mammals and invertebrates.

But despite the close association of many lizard species to spinifex, we still don’t know exactly why reptiles like it so much.




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Three ideas dominate. First, spinifex may contain lots of food for lizards, such as termites or ants.

Alternatively, the spiky, needle-like leaves of spinifex may offer small lizards a great place to hide from predators. And finally, temperatures deep within a dense spinifex hummock can be very cool compared to the searing desert heat, where temperatures can reach a scorching 50℃.

My research aim is to work out which, if any, of these explanations is true. I do this by measuring variables such as temperature, invertebrate abundance and risk of becoming prey, in spinifex and other plants.

Alongside my supervisors, I have also conducted behaviour trials on a couple of spinifex-loving lizard species: the mallee ctenotus (Ctenotus atlas) and the mallee dragon (Ctenophorus spinodomus).

Setting up behavioural trial enclosures. After more than 100,000 recorded observations, we are only beginning to better understand why lizards like using spinifex.
Kristian Bell, Author provided

We have recorded 230,000 temperatures, caught 16,089 invertebrates, constructed 112 lizard models and classified 143,627 behavioural observations. But such is the complicated nature of the work, we’re only partially closer to understanding the lizard-spinifex relationship. So far, our data suggests temperature is a key component.




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The photos below are generally a result of good fortune and spending inordinate amounts of time in wild places. Pictures of some of the smaller, more skittish animals were taken upon release from pitfall traps.

A close-up of mallee ctenotus, a striped lizard
Mallee ctenotus (Ctenotus atlas)
Kristian Bell, Author provided
A profile of a mallee dragon
Mallee dragon (Ctenophorus spinodomus)
Kristian Bell, Author provided

The above two photos show my study species: the mallee dragon and the mallee ctenotus. Despite one lizard being a skink and the other a dragon, both species are strongly associated with spinifex. The skink tends to forage within spinifex, whereas the dragon emerges into open patches adjacent to spinifex to eat and “signal” to other dragons.

Spinifex with a rainbow in the background

Kristian Bell, Author provided

Spinifex grass, pictured above, with its spiky, needle-like leaves, creates valuable habitat for numerous species of birds, mammals and invertebrates — not just reptiles. Its abundance and influence on many species make it a “foundation species”.

Burton's legless lizard
Burton’s legless lizard (Lialis burtonis)
Kristian Bell, Author provided

This photo above shows a Burton’s legless lizard (Lialis burtonis) — a predator of my study species. These snake-like reptiles are specialist lizard hunters and often use the dense cover of spinifex to their advantage to ambush passing lizards.

Legless lizards might look a bit like snakes, but they have different ancestries and subtle distinguishing features, such as the lizard’s eyelids and external ears, which snakes don’t have.

But many other animals live in or near spinifex, and would happily make a meal of small lizards, including those shown in the following photos. The ability of numerous predators to access the centre of spiky spinifex clumps throws some doubt on the idea spinifex is used as protection from predators.

slender-tailed dunnart
Slender-tailed dunnart (Sminthopsis murina)
Kristian Bell, Author provided
A soaring black shouldered kite
Black shouldered kite (Elanus axillaris)
Kristian Bell, Author provided
Dwyers snake, with a researcher in the background
Dwyers snake.
Kristian Bell, Author provided
Sand monitor
Sand monitor.
Kristian Bell, Author provided

We can’t claim to have cracked the case yet. But we’re a step closer to unravelling the secrets behind one of Australia’s remarkable, and under-appreciated, biodiversity stories.




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The Conversation


Kristian Bell, PhD candidate, Deakin University

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

I walked 1,200km in the outback to track huge lizards. Here’s why



Sophie Cross, Author provided

Sophie Cross, Curtin University

In 2017 and 2018 I walked the equivalent of 28 marathons in the scorching Western Australian outback. Why, you ask? To assess how some of Australia’s largest lizard species interact with restored mines.

As part of my PhD research, I hiked in often extreme heat on a mine site in WA’s sparsely populated Mid West region. My fieldwork was both physically and mentally demanding, as I spent many hours each day walking through the bush looking for signs of monitor lizards.

Being in a remote location and mostly alone, I had plenty of time to ponder the wisdom of my career choice, particularly on days when temperatures exceeded 40℃ and not even the lizards ventured from their homes.

Pushing through these mental challenges was difficult at times, but my work has provided me with some of my most rewarding experiences. And what I discovered may be crucial for restoring habitats destroyed by mining.

Restoring abandoned mines

Habitat loss is a leading cause of biodiversity loss worldwide. Although mining typically has a smaller environmental footprint than other major industries such as agriculture or urbanisation, roughly 75% of active mines are on land with high conservation value.




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There are around 60,000 abandoned mines in Australia, but very few of them have been officially closed. How to restore them is a growing public policy problem.

Sophie Cross walked more than 1,200km and tracked a young-adult perentie to find out whether they were using a restored mining area.
Author provided

Recovering biodiversity can be an exceptionally challenging task. Animals are vital to healthy ecosystems, yet little is understood about how animals respond to restored landscapes.

In particular, reptiles are often overlooked in assessments of restoration progress, despite playing key roles in Australian ecosystems.




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Do animals return to restored habitats?

I wanted to know whether restored habitats properly support the return of animals, or whether animals are only using these areas opportunistically or, worse still, avoiding them completely.

To study how reptiles behave in restored mining areas, I hand-caught and tracked a young adult perentie. The perentie is Australia’s largest lizard species, growing to around 2.5m in length, and is an apex predator in arid parts of the country.

I tracked the lizard for three weeks to determine whether it was using the restored area, before the tracker fell off during mating.

The tracking device revealed how the perentie navigated a restored mine, before it fell off during mating.
Author provided

Previous methods of tracking assume the animal used all locations equally. But I used a new method that measures both the frequency with which animals visit particular places, and the amount of time they spend there. This provided a valuable opportunity to assess how effective restoration efforts have been in getting animals to return.

Restoration needs more work

My research, published this week in the Australian Journal of Zoology, shows that while the perentie did visit the restored mine, it was very selective about which areas it visited, and avoided some places entirely. The lizard went on short foraging trips in the restored mine area, but regularly returned to refuge areas such as hollow logs.

The method used GPS and a VHF tracking antenna to follow the perentie.
Author provided

This is because hot, open landscapes with minimal refuges present high risks for reptiles, which rely on an abundance of coverage to regulate their body temperature and to avoid predators. Such costs may make these areas unfavourable to reptiles and limit their return to restored landscapes.

In comparison, undisturbed vegetation supported longer foraging trips and slower movement, without the need to return to a refuge area. Unfortunately, areas undergoing restoration often require exceptionally long time-periods for vegetation to resemble the pre-disturbed landscape.




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How can we help reptiles move back into restored areas?

Restored landscapes often lack key resources necessary for the survival of reptiles. As vegetation can require a long time to reestablish, returning fauna refuges like hollow logs and fauna refuge piles (composed of mounds of sand, logs, and branches) could be crucial to aiding in the return of animal populations.

My research team and I have called for animals to be considered to a greater extent in assessments of restoration success. In the face of increasing rates of habitat destruction, we need to understand how animals respond to habitat change and restoration.

Failing to do so risks leaving a legacy of unsustainable ecosystems and a lack of biodiversity.The Conversation

Sophie Cross, PhD candidate, Curtin University

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

Lizards: Global Warming


The link below is to an article that reports on the impact of global warming on cold climate lizards.

For more visit:
http://science.nbcnews.com/_news/2013/03/08/17238399-warming-planet-killing-off-cold-climate-lizards-says-study