Over the course of recorded time, many species have been threatened with extinction. Once-powerful animal empires - like the dinosaurs - have been completely wiped from the planet. But others once on the verge of disappearance have survived, bounced back, and even reclaimed their kingdoms. The British monarchy is also responsible for the survival of another once-rare species. In 19th century China, only one herd of an unusual deer known as "milu", remained. When a flood destroyed the walls of the Emperor's garden, the deer were wiped out. Luckily, a few had been smuggled out years before. The Duke of Bedford took them under his protection and now Pere David's deer survive not just in - but because¬ of - captivity.

pt. 1. Rebuilding an Empire: Pere David's Deer -- pt. 2. Rebuilding an Empire: The Mute Swan -- pt. 3. Rebuilding an Empire: Gopher Tortoise.