Geography & Climate
Although pantano means ‘swamp’ in both Spanish and Portuguese, the Pantanal is not a swamp but a vast alluvial plain. In geological terms, it is a sedimentary basin of quaternary origin, but its vastness led the early settlers to mistake it for a sea, which they called the Xaraés. This began to dry out, along with the Amazon Sea, 65 million years ago.
The Pantanal – 2000km upstream from the Atlantic Ocean yet just 100m to 200m above sea level – is bounded by higher lands: the mountains of the Serra de Maracaju to the east, the Serra da Bodoquena to the south and the Serra dos Parecis and Serra do São Geronimo to the north. From these highlands the rains flow into the Pantanal, forming the Rio Paraguai and its tributaries (which flow south and then east, draining into the Atlantic Ocean).
During the wet season (November to March), the rivers flood their banks, inundating much of the low-lying Pantanal and creating cordilheiras (vegetation islands above the high-water level), where the animals cluster together. The waters reach their high mark – up to 3m – in January or February, then start to recede in March. This seasonal flooding has made systematic farming impossible and has severely limited human incursions into the area. However, it does provide an enormously rich feeding ground for wildlife.
The floodwaters replenish the soil’s nutrients, which would otherwise be very poor, due to the excessive drainage. The waters teem with fish, and the ponds provide protective niches for many animals and plants. Enormous flocks of wading birds gather in rookeries several square kilometers in area.
Later in the dry season, the water recedes, the lagoons and marshes dry out and fresh grasses emerge on the savanna (the Pantanal’s vegetation includes savanna and forest which blend together, often with no clear divisions). The hawks, storks and caiman (jacaré) compete for fish in the remaining ponds. As the ponds shrink and dry up, the caiman crawl around for water, sweating it out until the rains return.