A lion rests in the grass of the Serengeti plains.

A close-up of a male lion at Duba Plains Camp in the Okavango Delta reveals scars of old wounds.

An adult male lion rests in the Serengeti. Loss of prey species, loss of habitat, and human encroachment have caused their numbers to precipitously decline. They are listed as vulnerable to extinction by the IUCN.

Social licking helps to reinforce bonds within the pride.

Vumbi females, stressed and fiercely protective of their young, get cross with C-Boy, an adult male, even though he's one of the resident fathers.

A lioness from the Barafu pride in Serengeti National Park wrangles her infant cubs.

An adult male lion, C-Boy, and a Vumbi female relax between matings.

Members of the Vumbi pride set out on an evening hunt.

A pair of lion cubs from the Barafu pride play with their mother's tail.

Lionesses and cubs from the Vumbi pride rest on a kopje, a rocky outcrop, near a favourite water hole.

Lions take advantage of dust to create confusion in the buffalo herd and make a successful kill.

When hunting finally stopped in what is now the Solenda game reserve, there were two lions left. Today there are nearly 100.

Two lionesses in Selinda survey the water for danger as they make the first crossing.

The lion cubs were reticent to cross at the river at first. Life is tough for these youngsters; most don't reach adulthood.

A lion roams in Chobe National Park, a wildlife conservation area near Kasane, Botswana.

Lions hunt buffalo in the wetlands of Duba Plains Camp in Botswana’s Okavango Delta, where National Geographic Explorers-in-Residence Beverly and Dereck Joubert researched their film and book Relentless Enemies: Lions and Buffalo.

Lions play in the Okavango Delta.

A lion drinks from a watering hole on Chief’s Island, in the Okavango Delta’s Moremi Game Reserve.

A lion relaxes on a tree branch at Lake Manyara National Park in northern Tanzania.

Lion cubs rest near a watering hole in Tanzania’s Serengeti National Park.

A lion sleeps in the plains of Serengeti National Park. The picture was taken by a camera-mounted robot car.

Lions search for prey in Serengeti National Park.

A lioness sits with her cub in Tanzania’s Ngorongoro Conservation Area.

A lion wanders the dry Nossob riverbed in the Kgalagadi Transfrontier Park, near the border of two protected areas: South Africa’s Kalahari Gemsbok National Park and Botswana’s Gemsbok National Park.

A lioness descends a tree at Masai Mara National Reserve, in the Narok County of Kenya. The reserve is contiguous with Tanzania’s Serengeti National Park.