Wildlife populations in the world-famous Masai Mara reserve in Kenya have crashed in recent decades, according to new research.
The research, published in the Journal of Zoology, used monitoring data from the past 33 years to calculate trends in wildlife populations across the reserve and on adjoining ranches. Although previous studies had already shown declines in some large mammal populations, this latest research covered a longer period and looked at more species.
In total, 12 species of large mammal were investigated, as well as ostriches and domestic livestock. The researchers also looked at changes in the numbers of migratory wildebeest and zebras coming into the Mara each year.
Large mammals in decline
“We were very surprised by what we found,” said Dr Joseph Ogutu, one of the scientists who undertook the research. “The Mara has lost more than two thirds of its wildlife.”
Of the 13 large species studied, only ostriches and elephants have not shown large declines outside of the reserve. Inside the Masai Mara itself, only the eland, Grant’s gazelle and ostrich have shown any signs of population recoveries during the last decade.
The numbers of migrating wildebeest and zebra have also drastically declined, despite relatively few changes in their populations in the neighbouring Serengeti, where the migrating animals come from. The epic wildebeest migration now involves 64% fewer animals than in the early 1980s.
During the wet season, when there is no migration, resident wildebeest in the Masai Mara have almost completely disappeared, while resident zebra populations have crashed by about three quarters.
Threats to wildlife in the Mara
The declines in the Mara’s wildlife are particularly surprising given major conservation efforts and an increase in local policing in the last decade. The main causes of the declines are thought to be poaching, changing patterns of land use on ranches, and a dramatic increase in the numbers and distribution of domestic livestock.
The researchers found that the number of cattle grazing in the reserve has increased by over 1,100%, while the density of sheep and goats has increased more than seven-fold. Heavy grazing is believed to be displacing wildlife, as well as making larger species more vulnerable to starvation during the severe droughts that have hit the region in recent decades.
Protecting wildlife in the Mara
If the decline in wildlife populations in the Mara is to be halted, the researchers say that the expansion of human settlements, livestock numbers and fencing needs to be regulated, and poaching needs to be brought under control.
“Otherwise, the status of Masai Mara as a prime conservation area and premier tourist draw card in Kenya may soon be in jeopardy,” said Dr Ogutu.
Liz Shaw, ARKive Species Text Author