Anhinga

The Anhinga swims lower in the water than many other birds due to its reduced buoyancy—a result of wetted plumage and dense bones. When at the surface, they tend to swim low in the water, often with only the neck and head above the water and sometimes with only the bill exposed. The Anhinga is also an adept soarer. While soaring, it holds its wings flat and straight, its neck outstretched or held with a slight kink; its long, straight tail is conspicuous. Anhingas often use thermals for soaring, and may achieve altitudes of several thousand feet.