Between the cities of Guayaquil and Duran, in the Guayas River, you will find Santay Island and Gallo Island. Originally formed by sediment build-up, these islands are now surrounded by mangrove trees. Within the island’s ring of mangrove trees, and as evidence of the island’s continuous interaction with the river, there is a large plain that overflows in winter. This wetland is important to waterfowl for whom it is an important nesting site.