Wildlife in the Mara has reduced by over 70% in the last 30 years and the drop is continuing.
This is according to the latest research published in the Journal of Zoology.
However, the number of cattle grazing in the reserve has increased by more than 1100% per cent, although it is illegal for them to so do.
One of the researchers Joseph Ogutu, says that even after renewed conservation efforts began in 2001, the numbers are still falling.
The Masai Mara is one of the biggest tourist attractions in the country, bringing in billions of shillings in foreign exchange.