Uganda lions in danger

The study was partly funded by the National Geographic Society, the Scientific Exploration Society, a Rufford Small grant, the School of Earth and Environmental Sciences, and the Siemiatkowski Foundation.

Instead of using the aerial and radio-collaring surveys, the researchers drove more than 8 000 km in 93 days searching for lions in the Queen Elizabeth Conservation Area in Southwestern Uganda.

After obtaining 165 lion detections and using individual identifications from photos, they calculated that on average one could expect to find about 3 individual lions per 100 square kilometres, they concluded that there could be a total of 71 lions in the Queen Elizabeth Conservation Area.

They also used the same 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,” the researchers say.

They point out that 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 Convention on International Trade in Endangered Species (CITES) report suggested that only about 25,000 remain in the wild, across 102 populations in Africa.

According to the researchers, however, the numbers in the CITES report are not 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traditional survey approaches – like counts of lion footprints, audio lure surveys or expert opinion – and many were not peer-reviewed.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.

Counting lions better

The researchers used what they says are better ways of counting lions; the spatially explicit capture-recapture methods which have proved useful for conservation and have for over a decade been used to count tigers, leopards, jaguars and mountain lions. They are only now becoming popular for lions.

“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,” the researchers say in an article about their study published in `The Conversation’; a network of not-for-profit media outlets that publish news stories written by academics and researchers.

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.

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.

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.

The researchers recommend the use of this relatively novel survey methodology to assess other lion populations across Africa. They 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.

“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,” they say.

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