What took me so long, I know, I know.
They are the only animals in Africa big enough to keep elephants and giraffes in check. Who are very big eaters in their own right which depletes food avaliable to all the others. They also sort out the zebra's and wildebeest.
Their operation grounds are grasslands and forests. They live in prides (one adult lion, several lionesses and the offspring of said lion). Their population is declining as well (for obvious reasons again)
