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Why is drag less important in air than in water?
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Locomotion
These birds largely reside in coastal areas of North America, although some populations live in the continent's interior along large rivers.
Drag is a force that resists movement through a fluid, such as air or water. While animals in both environments encounter drag, it is less significant in air than in water primarily because air has much lower viscosity and density than water.12
In aquatic environments, drag is a primary force retarding forward movement, resulting largely from the friction of water flowing over an animal's surface and the water's adherence to that surface. Because water is more viscous, its flow tends to be lamellar, and as speed increases, turbulence develops, which significantly increases drag. In contrast, the reduced density and viscosity of air mean that animals moving through it experience less of this resistive force.1