Castaways 10

No sooner had he waded into Cumberland Bay than Selkirk was overcome with fear and regret. He begged to be allowed back, but Stradling took great pleasure in refusing. Selkirk read his Bible, resigned to waiting for what he thought would be a few days, until another ship sailed by. He was wrong by four years and four months.
He found a cave on the beach, from which he barely moved for the first eighteen months. Frequent tree-snapping gales brought him to ‘a state of terror and dejection.’ He regretted the decision to abandon his ship and crewmates, shackled himself to the hope for rescue, and became ever more
‘...dejected, languid, and melancholy, scarce able to refrain from doing
 himself violence, till by degrees, by the force of reason, and frequent
 reading of the Scriptures, and turning his thoughts upon the study of
 navigation, after the space of eighteen months, he grew thoroughly
 reconciled to his condition.’

He initially survived on fish, which ‘occasion’d a Looseness’ in his bowels, and then turtle meat, ‘till it grew disagreeable to his stomach, except in jellies.’ Despite the fact that he was surrounded by ocean, he craved the inaccessible salt it contained. But he also had shellfish, and learned to boil the giant crayfish with his pepper berries, and managed to kill an occasional seal with his hatchet.
When his beach was invaded by hundreds of mating southern elephant seals, nineteen feet long and weighing up to two tons, their nocturnal wailing, and the approaching winter cold rain and howling winds funneled through the canyons, drove him to his senses, and inland.
In a grove of shade trees beside a stream on high ground, Selkirk built himself two huts out of pimento trees, with roofs of thatched grass. He constructed a crude bed, and covered it, and the huts’ walls, with skins from the feral goats he shot.
When his gunpowder ran out, he learned how to run them down on foot.

‘When he was himself in full vigour, he could take at full speed the
 swiftest goat running up a promontory, and never failed of catching
 them but on a descent... It happened once to him, that running on the
 summit of a hill, he made a stretch to seize a goat, with which under
 him, he fell down a precipice, and lay helpless for the space of three
 days, the length of which time he measured by the moon's growth since
 his last observation.’

The goat he landed on had cushioned his fall, and likely saved him from a broken back. Alex hamstrung some of the captives, and domesticated their kids, to provide him with milk and meat, with which he prepared ‘a hearty goat broth with turnips, watercress and cabbage palm, seasoned with black pimento pepper.’ Goatskins were sewn into garments, with a Cinque Ports nail he had fashioned into a makeshift needle.  When his original ship’s knife finally wore out, he forged new ones from iron barrel staves he had found on the beach. He cut his name into the trees.
The big fierce ships rats that had overrun the island tore at Selkirk’s clothing and feet as he slept. His solution was to tame the feral cats that had arrived with them, into bed companion exterminators.