Boulders Beach is a sheltered cove of granite and white sand at Simon's Town, near Cape Town. A few thousand African penguins nest on it out in the open, a couple of metres from the rail. All of them descend from two pairs that came ashore here in 1982. A boardwalk drops you level with the sand, and they preen, doze and shuffle between the rocks without paying you the slightest attention. The noise is the first surprise. They were long called jackass penguins for a bray that sounds startlingly like a donkey, and it carries across the cove from dawn to dusk; a bird brays to call in a mate, to greet its partner and to warn off a rival. Pairs stay together for life and come back to the same scrape in the sand or under the same bush each season, so there is rarely a visit without grey downy chicks calling at a parent in from the sea. Late in the day the granite turns gold and long shadows rake the beach.
The cove next door is the one you can get into. The boulders take the swell off False Bay, so the water inside stays calm, and swimmers wade into the same shallows the colony fishes. Penguins porpoise past snorkellers without breaking stride, which happens in very few places on Earth. The rock doing all that sheltering cooled underground about 540 million years ago, before animals with backbones had spread across the planet. What it shelters now is a species in trouble: the African penguin is critically endangered, and this is one of only two colonies on the mainland you can walk beside at all. Once a year every adult sheds all its feathers at once, and until the new waterproof coat grows in it cannot go into the sea to feed. So it stands on land for about three weeks, fasting, living off fat it laid down in advance and losing nearly half its body weight. The scruffy bird standing well back from the water's edge is not sick. It is waiting to be waterproof.