In general, Costa Rica is a land of high volcanic peaks and thick tropical forests, but in the far north, adjacent to the country’s border with Nicaragua, the Caño Negro wetlands spread out in a tangled expanse of marshes, reed islands and sinuous channels. The ecosystem is fed by the Frío River, which meanders its way across the international frontier into Lake Nicaragua, at 3,190 square miles the largest lake in Central America.
During the rainy season (May to October) the river overflows its banks to form the Caño Negro Lagoon, a huge cloud mirror that is located directly beneath the flyway for migrant North and South American birds. Vast flocks of waterfowl, along with storks, spoonbills, ibis, anhingas and cormorants, arrive to overwinter at the beginning of the dry season each December. For the next four months, the water level falls gradually until all that is left is the main channel of the Frío. Then, the migrants depart.
As well as more than 400 recorded species of birds, the Caño Negro National Wildlife Refuge is home to elusive mammals such as jaguars, pumas, ocelots, tapirs and peccaries. Even the dorsal fins of large bull sharks can sometimes be seen slicing through the surface of the lagoon (owing to the fact that Lake Nicaragua is joined to the Caribbean Sea by the 112-mile-long San Juan River).
After a bumpy two-hour drive along rutted dirt roads from ORIGINS lodge, we came to a small town called, somewhat unsurprisingly, Caño Negro. There, a number of flat-bottomed boats were tied up to a jetty. As we seemed to be the only visitors that day, we had one of the crafts to ourselves, apart from its captain and an English-speaking guide. Heading out into the lethargic flow of the Frío, we immediately spotted several caimans, the alligator species native to Central and South America, basking in the sunshine on a sandbar. The trees lining the riverbank sheltered noisy troops of howler monkeys, as well as huge orange iguanas that had, bizarrely, taken up residence in the branches 30 or 40 feet above the ground.
As we drifted slowly downstream, it was quickly apparent that the reserve is a bird watcher’s paradise. Virtually every log or tree stump appeared to host a large and spectacular species. Preoccupied with binoculars and an identification book — our guide also had a Central American bird app on his phone — time slid past imperceptibly. But after more than two hours, the captain turned the boat around and we began to forge upstream. Instead of returning directly to the jetty, however, we headed into a narrow channel that abruptly opened out into the lagoon. There, herons, egrets, ibis and spoonbills stalked the shallow water, while innumerable species of ducks and geese searched for food along the margins of grassy islands.
It was a scene that reminded me once again not only of Costa Rica’s astonishing biodiversity, but also of the extraordinary fecundity of nature. Even if you have never taken a bird-watching trip in your life, and have hitherto felt little desire to go on one, I strongly recommend that you spare a morning of any Costa Rica vacation to experience the stirring beauty of the Caño Negro wetlands.