- Hippos break into smaller groups during droughts in the Kruger National Park, research shows.
- According to an ecologist, hippos move to places where they do not have to compete for grass and water pods.
- While some hippos have died because of droughts in 2015 and 2016, their numbers are on the increase again.
- For climate change news and analysis, go to News24 Climate Future.
Hippos that usually spend time in big, deep pools with many other animals tend to become less social during drought, research shows.
SANParks researchers initiated a long-term study on the hippo population in the Kruger National Park, which is the largest reserve in the country, to understand how hippos respond to drought and influence the environment and surrounding species. They monitored hippo populations before and after the 2015 and 2016 drought - which is considered the "most intense regional droughts" recorded, SANParks said in a report about the research.
They found that in times of drought, hippos move to places where they do not have to compete with other hippos for grass and water pods. Sometimes they have to walk far and die on the journey.
"Across all six rivers in Kruger National Park, the number of hippos decreased by about 2 500 individuals (38.6%) from just before the drought in 2015 to the same time in 2016," the report read.
"The number of hippos decreased by another 8% in 2017 when the drought ended."
"That drought [2015/2016] resulted in about half of the hippos we had in Kruger succumbing," said Dr Sam Ferreira, a large-mammal ecologist from SANParks.
Ferreira explained that hippos are active at night, leaving pools to feed off grass because their skin is sensitive to the sun.
"These unique features make hippos ecologically important and vulnerable to drought," SANParks said in its report.
Ferreira said SANParks flies a helicopter over the rivers every year and records the hippos they see and where they are.
During the drought, researchers found fewer hippos near the rivers, especially in areas where most hippos were found before the drought, the report indicated. The hippos also moved in smaller groups, as opposed to large clusters with other animals.
"While elephants, rhinos and other megaherbivores often move to areas with greener vegetation during droughts, hippos have a limited ability to migrate long distances due to their territoriality. Nonetheless, hippos moved to new areas on Kruger's rivers and altered their social behaviour in response to the severe drought," SANParks said.
Ferreira said hippos are an essential part of the Kruger National Park's natural system and can generate areas for other species to graze.
Hippos are also important in maintaining the quality of the water in rivers and keeping them open, by creating little pathways for water to flow where they walked.
Ferreira said:
What is important for us is to ensure that our river systems function and flow even in dry periods so that there are smaller pools for the hippos to use.
Since these droughts, the hippo population in the Kruger has risen.
"Now again, we are seeing our hippos increase again in Kruger after the drought. We are probably half-way back to about 7 000 hippos already since 2017, when the drought finished," Ferreira said.
