Getting closer to a much better count of Africa’s lions



A young lion cub rests in the branches of a large euphorbia tree in Uganda’s Queen Elizabeth Conservation Area.
Alex Braczkowski, Author provided

Alexander Richard Braczkowski, Griffith University; Duan Biggs, Griffith University; James R. Allan, University of Amsterdam, and Martine Maron, The University of Queensland

African lions are one of the world’s favourite animals. But their numbers have been shrinking over the past century, especially over the past 30 years. Some scientists estimate that their numbers have halved since 1994.

Estimates of the total population of Africa’s king of beasts vary, but a recent CITES report suggested that only about 25,000 remain in the wild, across 102 populations in Africa. But the numbers in this report aren’t particularly reliable. Most used traditional survey approaches – like counts of lion footprints, audio lure surveys or expert opinion – and many were not peer-reviewed.

These traditional methods of counting lions produce highly uncertain estimates. A count of lions using their footprints may give you an estimate of, say, 50 lions in an area. But the uncertainty around this estimate could be between 15 and 100 individuals. This large uncertainty makes tracking how lion populations change from year to year nearly impossible. Our recent review shows that the majority of methods used to count African and Asiatic lions use these less robust methods.

Two young lions rest in the branches of a Euphorbia tree on the Kasenyi Plains of Queen Elizabeth National Park.
Alex Braczkowski

Making sure that lion numbers are accurate and reasonably precise is key for the species’ conservation. Estimates of lion numbers underpin their classification as ‘vulnerable’. They also form the backbone for controversial management practices like the setting of trophy hunting quotas.

The good news is that better ways of counting lions are being developed. So called spatially explicit capture-recapture methods are useful for conservation because they tell us not only how many animals live in an area, but how they move in a landscape, what their sex ratios are and even where their highest numbers are located. This method has been used to count tigers, leopards, jaguars and mountain lions for over a decade but it is only now becoming popular for lions.

A review of 169 peer-reviewed scientific articles (Web of Science and Google Scholar) showed many lion abundance and density estimates rely on traditional methods like audio lure or track surveys.

Spatially explicit capture-recapture methods use a mathematical model which incorporates the individual identity of animals (usually from photographs of natural body markings, spot patterns or even whisker spots) and their location in a landscape. By identifying and “marking” individuals over a period of time an estimate can be made of the total number of animals that live in an area.

Better methods from East Africa

This method was first used to count lions in a 2014 study in Kenya’s Maasai Mara. The lead authors capitalised on a historic way of identifying lions: their whiskers. Every lion in the wild has a unique whisker spot pattern, very much like a human fingerprint.

Recently, some of us applied this technique in a count of African lions in southwestern Uganda, in a region known as the Queen Elizabeth Conservation Area. These lions are interesting because they have a rare culture of tree-climbing. This means they have great local tourism value as each lion raises about USD$ 14 000 annually in park fees.

The status of lions in Uganda was not previously very well understood. After a wave of intense poaching during the unstable Idi Amin and Milton Obote regimes – 1971 to 1985 – during which time wildlife numbers plummeted.

But recent aerial surveys and radio-collaring studies suggested that lion prey numbers were recovering. A radio collaring study of lions from 2006 to 2010 also showed that lion home range sizes were small, and because range size is predicted by abundant prey, this suggested lions here were in good health.

Uganda’s lions in peril

From October 2017 to February 2018 we drove more than 8 000 km in 93 days searching for lions in the Queen Elizabeth Conservation Area. We obtained 165 lion detections. Using individual identifications from photos, we calculated that on average one could expect to find about 3 individual lions per 100 square kilometres, with a total of 71 lions in the entire area.

Scientists during a census of the lions in Uganda’s Queen Elizabeth Conservation Area.
Steve Winter

We used the spatially explicit capture-recapture method to assess how lion movements had changed from the home range study performed a decade earlier. Worryingly, our results showed that lions had increased their ranges significantly in just 10 years – above 400% for male lions and above 100% for females.

Also, there was only one female for every male in the wild. This is very different to other African lion populations which have a much higher proportion of females relative to males (about two females for every male).

Next steps

From the standpoint of lion conservation and recovery these results are concerning. But, on a positive note, this finding has provided a timely alert. And we recommend the use of this relatively novel survey methodology to assess other lion populations across Africa.

Four young lion cubs trigger a camera trap set on a waterbuck kill on Queen Elizabeth’s Kasenyi Plains.
Alex Braczkowski

More recently, in 2020, another rigorous study at Lake Nakuru National Park, Kenya, applied this approach and found that this method estimated lion population size to be about a sixth of what was previously thought. The Kenya Wildlife Service, in collaboration with local partners is now using spatially explicit capture-recapture in an ambitious nationwide survey of lions and other large carnivores at all potential strongholds across Kenya.

More broadly, these results further bolster the view that by relying on ad hoc, indirect methods to detect lion population trends, we may end up with misleading answers and fail to direct scarce conservation resources optimally.

We argue that all stakeholders involved in lion conservation across Africa and Asia should use rigorous survey methods to keep track of lion populations. These results should then form appropriate baselines for continent-wide reports on lion abundance, and help inform strategies aimed at their recovery.The Conversation

Alexander Richard Braczkowski, Research Associate, Griffith University; Duan Biggs, Senior Research Fellow Social-Ecological Systems & Resilience, Griffith University; James R. Allan, Postdoctoral research fellow, University of Amsterdam, and Martine Maron, ARC Future Fellow and Professor of Environmental Management, The University of Queensland

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

A rare discovery: we found the sugar glider is actually three species, but one is disappearing fast



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Teigan Cremona, Charles Darwin University; Alyson Stobo-Wilson, Charles Darwin University; Andrew Baker, Queensland University of Technology; Steve Cooper, South Australian Museum, and Sue Carthew, Charles Darwin University

Most Australians are familiar with the cute, nectar-loving sugar glider (Petaurus breviceps), a marsupial denizen of forests in eastern and northern Australia.

However, our new study shows the sugar glider is actually three genetically and physically distinct species: Petaurus breviceps and two new species, Krefft’s glider (Petaurus notatus) and the savanna glider (Petaurus ariel).

This discovery has meant the distribution of the sugar glider has substantially reduced, and it’s now limited only to coastal regions in southeastern Australia. The devastating bushfires last summer hit this part of Australia hard.




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Summer bushfires: how are the plant and animal survivors 6 months on? We mapped their recovery


Our new species from northern Australia, the savanna glider, is particularly at risk, living in a region that’s suffering ongoing small mammal declines. We must urgently assess the conservation status of both the sugar glider and savanna glider before they’re lost.

These gliding abilities likely evolved to adapt to Australia’s open forests.
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Nature’s BASE-jumpers

Our discovery of new Australian mammal species is rare and exciting. That’s because while Australia is filled with hidden and undiscovered animal and plant diversity, our mammal fauna is considered relatively well known, with more than 99% of all species scientifically described.

Perhaps Australia’s most graceful mammals, species of the genus Petaurus (meaning “rope-dancer”) have the unique ability to expand the skin between wrist and ankle to glide from tree to tree – they are nature’s BASE-jumpers. It’s believed these gliding capabilities evolved as a way to adapt to the open forests of Australia.

The palm-sized sugar glider, named after its insatiable appetite for all things sweet, is the most widely known member of the genus and is commonly kept and bred in captivity around the world.

From the Aussie outback to London’s Natural History Museum

An investigation into sugar glider genetics a decade ago highlighted two divergent groups within the species, suggesting sugar gliders may represent more than one species.

In that study, scientists also unexpectedly found that one glider from Melville Island in the Northern Territory was genetically distinct from sugar gliders. Instead, this Melville Island glider showed a close relationship with two larger existing species, the squirrel glider (Petaurus norfolcensis) and mahogany glider (Petaurus gracilis).

Prompted by this unusual finding, we investigated the mysterious glider’s identity.

We studied more that 300 specimens from museums to the Aussie outback.
Teigan, Author provided

From some of the most remote areas of outback Australia to our vast national museum collections, and ultimately the hallowed halls of London’s Natural History Museum, we captured, measured and compared every glider we could find to evaluate their relationships.

Indigenous knowledge of the savanna glider Petaurus ariel and the contributions of local Aboriginal people were also invaluable to our investigation.

The savanna glider is culturally significant and valued across multiple language groups in northern Australia and we are grateful to the Traditional Owners for sharing their knowledge of the species and its habitat.

In the end, we assessed more than 300 live and preserved specimens and established three species where once there was one.

Meet the new gliders

The savanna glider lives in the woodland savannas of northern Australia and looks a bit like a squirrel glider with a more pointed nose, but much smaller. The remaining two species look similar to each other and may overlap in some areas of southeastern Australia.

Sugar gliders are restricted to forests East of the Great Dividing Range.
Michael J Barritt, Author provided

Krefft’s glider has a clearly defined dorsal stripe and fluffy tail. It is widespread in eastern Australia and has been introduced to Tasmania.

The sugar glider, with a less-defined dorsal stripe, is apparently restricted to forests east of the Great Dividing Range, extending from southeast Queensland to around the border of New South Wales and Victoria.

What does this mean for sugar gliders?

Despite ongoing debate about the role of taxonomy (the science of classifying species) in conservation, it is clear from our work that species definitions provide an essential foundation for effective conservation.

Sugar gliders use tree hollows, which makes them vulnerable to intense bushfires.
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When considered as one species, sugar gliders were widespread, abundant and officially classified as “least concern”.

The distinction of these three species has resulted in a substantially smaller distribution for the sugar glider, making the species vulnerable to large scale habitat destruction, such as the recent bushfires.

And sadly, the bushfires have incinerated a large proportion of the sugar glider’s updated range. Given they are tree hollow users and require a diverse habitat with a variety of foods, the bushfires have most likely had a devastating effect on this much-loved species.




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The savanna glider is disappearing

Our work has shown urgent intervention is needed to save this important plant pollinator and icon of the Australian bush.

The savanna glider in particular is facing its own conservation concerns in the ongoing northern Australian small mammal declines. Tree-dwelling mammals are among those worst affected there, and it appears the savanna glider is no exception.

This is a rare discovery as most Australia’s mammals are considered already known.
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An earlier study of ours showed the species has undergone a 35% range reduction over the last 30 years, and is slowly disappearing from the inland areas it once inhabited. It’s likely feral cats, changed fire regimes and feral herbivores have played a significant role in the savanna glider’s vanishing range.

It would be a tragedy if this species is lost to the world just as it was discovered, especially with Australia’s appalling track record of human-induced mammal extinctions.




Read more:
Scientists and national park managers are failing northern Australia’s vanishing mammals


More scientific work is urgently needed. We must define the distinct ecology of each species and determine their distribution in more detail.

This will enable us to effectively assess the conservation status of each species and determine what management efforts are required to ensure their protection as they face an uncertain future.The Conversation

Teigan Cremona, Research Associate, Charles Darwin University; Alyson Stobo-Wilson, Postdoctoral Research Associate, Charles Darwin University; Andrew Baker, Senior Lecturer, Queensland University of Technology; Steve Cooper, Principal Researcher , South Australian Museum, and Sue Carthew, Provost and Vice President, Charles Darwin University

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