Oxbow lakes can be found wherever there is a winding river, and the many rivers of the Amazon have led to a correspondingly high number of oxbow lakes, which create their own unique habitats for a variety of wetland jungle species.

So what is an oxbow lake?

Simply, it’s when a meander in a river gets cut off from the main river due to erosion, forming an independent, crescent-shaped body of water.

Important Definition! Meander: extreme U-bend in the course of a stream, usually occurring in a series (www.britannica.com)

How does an oxbow lake form?

Since this is a naturally occurring process, it takes many years for oxbow lakes to form, but the process itself is pretty straightforward:

1. Sediment is deposited on the slow-moving interior side of the river’s bend (the convex bank).
2. The faster-moving current on the outside erodes the opposite (concave) bank, widening the river.
3. The neck of the meander grows narrower and narrower with the deposition and erosion of sediment on the banks.
4. Eventually, the neck is completely cut off from the river when the river creates a shorter, more direct path to the other side of the meander, thus leaving a crescent-shaped lake independent of the river.

Since they are completely cut off from the river, these lakes are stillwater, meaning that there is no water flowing in or out of it. This creates a nutrient-rich bog. On a visit Sacha Lodge, you might see examples of these lakes forming as you explore the Amazon.

What animals live in an oxbow lake?

While this varies depending on where you are, even within the Amazon, the most common wildlife you will see in an Oxbow lake in the rainforest are giant river otters and the fish they feed on. Many birds can also be seen visiting the lakes.

Why is it called an “oxbow” lake?

This name comes from its resemblance to an oxbow, the U-shaped piece of metal which is fixed to a yoke around an ox’s neck, used for plowing.