The Amazon River basin is a vast area covering about 40% of the South American continent, and it is responsible for about 20% of the world's fresh water. The hydrology is based on a wet-dry system that coupled with precipitation patterns can create very diverse microhabitats and account for highly variable water levels in the river tributaries. Depending on location, there can be river water level differences of up to 20 meters.

During the dry season, sand bars and beaches are exposed that provide habitat for nesting waterbirds like the Black Skimmer, Large-billed Terns, and Yellow-billed Terns. Terns and skimmers belong to the Order Charadriiformes that includes such groups as waders (sandpiper and plover-like waders), gulls and allies, and thick-knees and allies.

When the rains begin and the tributaries flood, waterbirds that use the exposed sand bars and sand beaches must find another location to spend the non-breeding season. Some may stay in the Amazon and go north of the equator where the tributaries are not flooded, some may go east to the coastal waters of Brazil and Argentina, while others may chose to leave the Amazon Basin entirely. These migration strategies are very under researched with only one waterbird project conducted on the Black Skimmer in Peru (Davenport et al. 2016).

In 2014, we tracked Black Skimmers nesting in Peru that appeared to have very diverse migration strategies heading east, south, and west from nesting locations in Manu National Park. To our amazement, not only did two individuals go west but they crossed the Andes Mountain range at altitudes of greater than 5,000 meters above sea level (Davenport et al. 2016). This was the FIRST ever documentation of a waterbird doing any such thing!

This year, we plan to go back to the Amazon and track more skimmers and start on life history research of the Large-billed Tern and Yellow-billed Tern and other waterbird species responses to changes in hydrology of the Amazon Basin.