The mangrove forest offers great advantages to many birds, especially those that feed on fish.
In a world surrounded by water, the mangroves provide vantage points where they can nest without fearing the land predators, and all around there are fish, invertebrates and small reptiles with which to feed their chicks, so when the breeding season comes round, the mangroves are adorned with an infinity variety of nests.
For the American jabirus, the mangrove boughs are impregnable fortresses in which to guard their chicks.
Here, there are no predators, and food can always be found, so of each clutch of eggs they lay, more chicks survive than in continental colonies.
In an apparent paradox, this ecosystem, which would appear at the very limit of the ecologically conceivable, is now being revealed as a rich, diverse world where animals and plants develop in their thousands free from the usual interference from man.
This is an intermediate world created by both between the waters of the sea and those of the rivers; a hybrid world which requires major osmotic adaptations, but in compensation offers almost inexhaustible food and shelter. The mixture of fresh water laden with new nutrients, and the salt water that gives rise to sedimentation favours the increase of invertebrates and fish, and this makes the austere wetlands and coves of the mangrove forest a meeting place for thousands of aquatic birds that come here each day to partake of the feast.
In the waters of the Cuban keys and islands where the mangrove grows, over a hundred different bird species can be found, the majority equipped with long legs for wading.
Each species has a beak specialised in catching a certain type of prey, so competition among them is reduced to the minimum.
This one, the brown pelican, the only strictly marine pelican, uses the technique of swooping down to catch fish from the air.
Others are much more sophisticated, and have prodigious beaks which are the result of millions of years of adaptations in order to filter the water.
No other beak in the mangrove swamp can compare with that of the flamingos.
Attracted by the microscopic crustaceans that proliferate in the brackish waters, thousands of them come to the mangrove swamps.
Their strange beaks are equipped with sieves that filter the water and retain the tiny crustaceans, and their stilt-like legs and webbed feet mean they can easily walk across the viscous slime.
Just a few decades ago, flamingos were very numerous in Cuba, but humans have destroyed the majority of their breeding colonies, and the last specimens today hide in the mangrove forests of the Main Island, where inaccessibility has become their greatest ally.
At twilight, great flocks of birds disturb the reigning peace at the edge of the mangrove forests.
The outer edge of this inhospitable ecosystem, where the aquatic birds gather to eat, is the best known and most tumultuous region of the mangrove forest. It is an open, exposed area, where the birds can be easily seen, and so at first it was believed that the majority of the wildlife was concentrated here.
But the impenetrable interior of the mangrove labyrinth hides shy, fascinating surprises.