Crocodiles in Salt Water

The long shape is a crocodile. Lago Enriquillo holds the only wild crocodiles left in the Dominican Republic and the largest gathering of American crocodiles anywhere in the Caribbean, somewhere around four hundred of them, living in water saltier than the sea.

They manage it in two ways. Their tongues carry glands that push salt back out again, and they know exactly where the fresh water is. Springs seep in along the shore, rivers come down off the mountains, and the crocodiles collect at those places to drink and to nest. They are unusually sociable about nesting. In one study most nests sat within about ten metres of their neighbours, all crowded into the same few workable metres of sand.

Out in the middle of the lake there is a low desert island called Isla Cabritos, and it is the only place on Earth where two kinds of rock iguana live side by side. One is the rhinoceros iguana, heavy and grey with horns on its snout. The other is Ricord's iguana, which lives nowhere but this one island of Hispaniola and is among the rarest lizards there is.

There used to be three islands. From about two thousand and four the lake began to rise, and it kept rising for nearly a decade. It more than doubled in area. It drowned close to nineteen thousand hectares of farms and pasture, swallowed the road to the border more than once, filled a customs building to its second floor, and forced the building of a whole new town for the families it pushed out. Two of the three islands went under and have not come back. Scientists still do not agree why. Polly watches the crocodile turn and go down.