Results of a recent survey of Uganda's national parks reveal that the numbers of African lions in the parks has decreased by more than 30 percent in the past decade.
Livestock owners have been implicated in the lion deaths, either poisoning the big cats to protect their herds or killing them in acts of retaliation, according to the Wildlife Conservation Society (WCS), which conducted the study alongside researchers from the University of St. Andrews.
"African lions are a vital component of these ecosystems," said WCS conservationist Edward Okot Omoya, the lead author of research published alongside the study in the journal Oryx. "They play an important role in disease control of antelopes and buffalo by killing the sick animals."
To count the lions in the parks, researchers surveyed three major conservation areas around Uganda. By broadcasting the call of a distressed calf over a loudspeaker mounted to a truck, lions, hyena and other large cats were lured to the source of the sound. Researchers were able to count 66 lions, 176 spotted hyenas, and seven leopards, along with scores of other small predators. Then, using the data gathered during the observations, the researchers generated an estimate of the total lions in the three conservation areas targeted in the survey.
The researchers estimate there are 408 lions in the three strongholds in Uganda, about 200 fewer than estimates made a decade ago.
The Queen Elizabeth Conservation Area saw an estimated 30 percent drop in lions from 206 to 144. In Murchison Falls Conservation Area, the team estimates there are 132 lions, almost 60 percent fewer than the 324 reported a decade ago. In Kidepo Valley National Park researchers detected an increase in estimated lion numbers, jumping from 58 a decade ago to 132 today.
"Lions are the species tourists most want to see in Uganda's savannas according to research by WCS. Surveys of tourists have shown that they would be 50 percent less likely to visit the parks in Uganda if they couldn't see lions, and if they did visit they would want to pay less for the experience. As an industry that generates more foreign currency in the country than any other business this could have significant consequences for Uganda," said Andrew Plumptre, WCS's Director for the Albertine Rift.
Based on their observations, the researchers suspect hyena numbers have also decreased, but they said there is not currently enough evidence to prove it.
"Conservation areas such as Queen Elizabeth and Murchison Falls, which formerly contained the highest biomass of mammals on Earth, depend on the delicate balance between predators and prey," said James Deutsch, Executive Director of WCS's Africa Program. "Their loss would permanently alter two of Africa's great ecosystems."