The buffel kerfuffle: how one species quietly destroys native wildlife and cultural sites in arid Australia

Buffel grass surrounding Hakea divaricata, a bushfood and medicine tree.
Ellen Ryan-Colton, Author provided

Christine Schlesinger, Charles Darwin University; Ellen Ryan-Colton, Charles Darwin University; Jennifer Firn, Queensland University of Technology, and John Read

Many of us are aware of the enormous destruction feral cats inflict on Australia’s native wildlife, but there’s another introduced species that will cause at least as much harm if left unmanaged — yet it receives far less attention.

We’re referring to buffel grass (Cenchrus ciliaris), a plant native to parts of Africa and Asia that has been widely introduced elsewhere for pasture and to stabilise soils.

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Buffel is fast growing, deep rooted and easy to establish, with each plant producing thousands of seeds. But these very characteristics for which it was prized have caused it to spread much further than ever planned.

We recently published two studies on buffel grass. One looked at just how serious the buffel invasion is to humans and wildlife by comparing it to other high-profile threats such as cats and foxes. The other study found that when buffel was removed, native wildlife quickly bounced back.

A catastrophic threat to wildlife

Buffel is now one of the worst invaders of dryland ecosystems worldwide. In Australia, this single species has replaced once diverse communities of native grasses and wildflowers across vast tracks of land. For example, most conservation reserves in the southern part of the NT have been invaded, including parts of Uluru-Kata Tjuta National Park.

Because it grows so thickly, the dense grassy fuel can feed bigger, hotter and sometimes unexpected fires. These new fires are a risk to wildlife, humans and large, old trees.

Buffel and fire affected shrubs starting to burn
Buffel grass promotes new fire risks.
Jennifer Firn, Author provided

Our study compared buffel to threats posed by changed fire regimes, feral predators (cats and foxes) and feral herbivores (rabbits and camels). We found buffel was equal to feral cats and foxes in terms of future risk to biodiversity.

Feral cats are currently listed as threatening some 139 species under national environment legislation, including the night parrot and the central rock rat. Each year across Australia, feral cats kill more than three billion animals.

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Buffel is formally listed as threatening 27 species under this legislation, such as the floodplain skink (buffel can choke its burrows). But because there has been much less research on the impacts of buffel, this number is likely a significant underestimate.

Unlike cats, buffel impacts whole plant communities and the animals they support. For example, when large old trees are burnt, birds that rely on tree hollows for nesting can no longer breed successfully.

Buffel grass surrounds bushfood wattleseed.
Buffel grass surrounding wattleseed, a bushfood.
Ellen Ryan-Colton, Author provided

What’s more, buffel has only spread widely in the last 20-30 years, which means its full impact on ecosystems has not yet been realised. In fact, 70% of the Australian continent has suitable conditions for buffel growth and could, in time, become invaded.

In contrast, cats have already roamed Australia for more than 200 years and, tragically, have caused many species, like the lesser stick-nest rat, to become extinct.

A social and cultural threat for Aboriginal people

Our study found buffel ranked higher than any other environmental threat in terms of its social and cultural impacts for Aboriginal people.

Because buffel is valued as a pasture grass in some regions, much debate has focused on its agro‐economic benefits versus environmental costs.

Meanwhile, the views and values of Aboriginal custodians of inland Australia have remained marginalised. It’s time this changes.

Nyanyu Watson showing how it’s harder to see animal tracks in areas occupied by buffel grass.
Ellen Ryan-Colton, Author provided

While feral cats and buffel both threaten culturally important wildlife, buffel is also causing the decline of valued plant foods and medicines.

For example, native desert raisin (Solanum centrale) — “katjirra” to Western Arrernte people and “kampuṟarpa” to Pitjantjatjara people — remains an important staple food across central Australia and is part of Australia’s living cultural heritage.

However, it is becoming harder for women to find and collect as buffel takes over country.

Buffel grass growing right under desert fig
Buffel grass growing right under desert fig, a bushfood that’s sensitive to fire.
Ellen Ryan-Colton, Author provided

Buffel also damages important cultural sites by bringing fire and choking water holes. Thick grass makes it difficult to walk through country and it’s now hard to see tracks or animals.

Together with the loss of species, this inhibits the transfer of cultural knowledge from one generation to another.

The return of native wildlife

Buffel responds well to herbicide in smaller areas, and spread can be slowed or stopped by treating isolated infestations.

For six years, we tracked the response of native plants and animals (particularly lizards) after buffel was treated at six sites in the Tjoritja National Park near Alice Springs. And we found biodiversity soon bounced back.

A buffel grass removal experiment, near Alice Springs.
Christine Schlesinger, Author provided

Following good rains, native plants like billy buttons and golden everlastings that had just been hanging on quickly re-established in areas where buffel was treated. And as native plant communities were restored, a range of lizards and other wildlife returned, too.

Birds such as Australian ring-neck parrots and red-tailed black-cockatoos began to selectively use the treated areas, foraging on seeds on the more open ground.

Ants also became much more abundant and diverse where buffel was removed. Ants play an important role in ecosystems, for example, by dispersing seeds. This has likely been diminished in buffel-occupied areas.

Fire-tailed skink
A fire-tailed skink at one of the the buffel removal sites.
Christine Schlesinger, Author provided

Importantly, while research demonstrates the potential for ecosystem recovery following effective control, the negative effects of buffel on fauna increased in areas where we did nothing.

Where to from here?

The findings from both our studies underline the urgent need for management on a much larger scale than what is currently possible, and prevention of further spread.

It’s clear a nationally coordinated response is required, along with policies that support positive local initiatives.

Creating and maintaining large buffel-free sanctuaries in areas not yet invaded could help to protect biodiversity in the future. But we found the cost of maintaining these could be an estimated 40–50 times more than other pest-free sanctuaries, if restricted to current methods of control.

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This is why Australia needs new, cost-effective, culturally appropriate and safe control options, rolled out on a broad scale. We stress the need for Aboriginal people from regions affected by buffel and prone to invasion to be central to discussions and the development of solutions.

It’s also important to note controlling buffel doesn’t require its eradication from pastoral regions where it’s valued. It does, however, require a national commitment and dedicated research, with strategic, coordinated and committed action.The Conversation

Christine Schlesinger, Senior Lecturer in Environmental Science and Ecology, Charles Darwin University; Ellen Ryan-Colton, PhD candidate, Charles Darwin University; Jennifer Firn, Professor, Queensland University of Technology, and John Read, Associate Lecturer, Ecology and Environmental Sciences

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


It’s getting hotter, so spiders are emerging. Should I be alarmed?

Golden orbweaver spiders may appear in your gardens.
Samantha Nixon, Author provided

Lizzy Lowe, Macquarie University and Samantha Nixon, The University of Queensland

In spring and summer every year, stories about “hordes of spiders” and “flesh-eating venom” fill tabloids and social media.

This rhetoric greatly exaggerates the relative risk of Australian spiders, leading to excessive pesticide use and unnecessary phobias.

There are more than 49,000 species of spiders in the world and around 4,000 of these live in Australia, many with astounding behaviours, beautiful colours and natural, biological pest control potential. We should be celebrating the diversity of our spiders in Australia — and what better time than right now?

Many insects and spiders have been growing over the winter months to emerge once the weather gets warmer. This means you’re probably going to start noticing more spiders around your house and garden. So which ones should you worry about?

St Andrews cross spider on its unique web
St Andrews cross spiders build beautiful, unique webs, and the spider sits with its legs in pairs.

Don’t fear these common household spiders

Some spiders like to live in houses. It’s cool, dry and there are hundreds of tasty insects to eat that you may not have even noticed, such as silverfish, book lice and springtails.

One of the most common spiders people find at home across Australia is, true to its name, the black house spider. These spiders build messy webs on fences and in the corners of windows.

Because they’re black, people can mistake these spiders for funnel-webs, but black house spiders are smaller and harmless. Also, a funnel-web will never make a web in your window.

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In your garden you may spot webs with a white cross (from St Andrews cross spiders, Argiope keyserlingi), with leaf retreats (from leaf curling spiders, Phonognatha graeffei), or golden silk (from golden orb weaving spiders, Trichonephila sp.). While impressive, these spiders are shy and their venom is harmless.

Even larger are huntsman spiders (from the Sparassidae family). While they’re famously fast moving, their bites are rare and, at worst, cause mild to moderate pain.

The good news is the vast majority of Australian spiders are harmless. In fact, a global study found less than 0.5% of spiders are dangerous to humans.

However, Australia is home to a number of “medically significant” spiders whose bites can be severe.

Huntsman spider on a tree
Huntsmans are huge, but generally harmless.

Funnel-webs are emerging from their burrows

First and foremost are funnel-web spiders, which are in the Atracidae family. Sydneysiders are likely well aware of the infamous Sydney funnel-web spider (Atrax robustus), but there are actually around 40 species of funnel-web spiders spread up and down the east coast of Australia.

Most funnel-webs will spend their lives hidden in their burrow. But during spring and summer, male spiders will wander about the bush (and sometimes back gardens) looking for mates, increasing the risk of human contact.

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Recent studies into funnel-web venom evolution have shown male Sydney funnel-webs have a high concentration of a toxin called “delta-hexatoxin”, which disrupts neuronal signalling and can lead to respiratory and cardiac failure. This helps them catch insect prey and defend themselves by causing pain in predators.

But through a quirk of evolution, this toxin can be fatal to humans.

The hexatoxins are distributed throughout the funnel-web family. To date, serious bites have only been reported from funnel-webs in southern Queensland and NSW. This includes the Sydney, Blue Mountains, Toowoomba/Darling Downs and the Northern Tree-dwelling funnel-web spiders.

Sydney funnel-web raising its legs
Funnel-web spiders spend most their lives hidden in a burrow.

Mouse spiders and redbacks

Mouse spiders (Missulena sp.) also have a toxin similar to hexatoxin in their venom, so their bites have similar effects. Like the funnel-webs, there are species of mouse spiders all over Australia.

Fortunately, clinical studies suggest serious mouse spider bites are rare, but these spiders should still be treated with caution.

Mouse spider crawling on a rock
Mouse spiders are best avoided.

And then there’s the renowned Australian redback spider (Latrodectus hasselti), with its striking red stripe. These spiders are found across the continent.

Redback spiders are related to American black widows and have toxins called latrotoxins, which also disrupt neuronal signalling in their prey. (It’s the female redbacks you need to keep an eye out for.)

Redbacks have a painful bite and symptoms can persist for several days. Fortunately for both redbacks and funnel-webs, effective antivenom treatments are available. If bitten, it’s always best to seek medical attention.

It’s worth noting no one has died directly from a spider bite in Australia in more than 40 years since the introduction of antivenom. So while Australian spiders may have a fearsome reputation, it’s somewhat overblown.

The infamous redback spider (Latrodectus hasselti) is one of Australia’s few spiders capable of serious envenomation.
Sam Robinson, Author provided

What to do with spiders in your house and garden

The first thing you should ask yourself is, do I need to get rid of them at all?

Spiders play an important role in the control of pests such as cockroaches and mosquitoes, so much so that each year, spiders eat more insect biomass than the weight of the entire human population.

A black house spider against a wall
Black house spiders build messy webs.

If you come face to face with an unwanted spider in your house, we recommend using a container and piece of paper for a simple catch-and-release into the garden. If the webs are what bothers you — and we’ve all walked face-first through a web at some point — sweeping them away will usually be enough for the spider to move on.

Alternatively, you can leave the webs in the garden to catch other insects (think of them as functional, miniature artworks).

Redbacks have a habit of building their webs under, for example, the rims of pot plants and in outdoor furniture. This can be a problem, especially for small children.

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So keeping your house and garden tidy, regularly sweeping and avoiding leaving junk lying around makes your garden less attractive for web-building.

It’s also good to avoid leaving shoes outside (or shaking them out) and checking your swimming pools for lost wandering spiders. This will help prevent accidental contact with funnel-webs during spring and summer.

Using amazing close-up footage, Sir David Attenborough explores the world of the redback spider.

If you really have to kill a redback, a quick squish with the shoe is far better than using pesticides, which have negative impacts on human health and the environment. This includes polluting streams, harming birds and bees, and leading to insecticide resistance in pests such as cockroaches and mosquitoes.

Spiders are a key part of Australia’s native ecosystems, including in cities. The harm we do to our own health and the environment by using excessive pesticides far outweighs the risk spiders pose to us.

If we can learn to live alongside these not-so-creepy crawlies, our houses and gardens will be better for it.

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The Conversation

Lizzy Lowe, Postdoctoral researcher, Macquarie University and Samantha Nixon, PhD, The University of Queensland

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