Friday, January 28, 2011

American Dipper

American Dipper

There are dippers along the Elbow River behind my home. The birds migrate south in the fall to feed along streams that are still open and that offer access to the aquatic invertebrates that are a principle source of nutrition. During spring they relocate north to nest and after breeding they will move even further north.  
These birds are the only truly aquatic passerines. They have their own Family (Cinclidae) and are related to thrushes. 
These birds are adapted to freezing-cold rushing water. With twice as many contour feathers as non-aquatic passerines and a thick coat of down, they are antithesis of the human snow birds; they seem to enjoy Canadian winters. Dippers preen a lot to maintain the waterproof and insulation properties of their feathers.  

Their eyelids are covered in white feathers and when they blink, the effect is startling.  
Their two most common feeding techniques are to either walk along the ice edge of the stream or paddle with their flippers in the turbulent water. Either way, they intermittently submerge their head and once they identify food, they dive and then walk along the bottom of the stream. Their stong legs and toes are adpated to walk on stream floors and their stubby wings are adapted to paddle on the surface.  

The ability to see both above and below water is fasciliated by iris muscles adapted to change the shape of the lens.

Their blood oxygen capacity is much higher than non-aquatic songbirds and allows them to remain sumerged for up to 30 seconds while foraging.


Sibley, David A. The Sibley Guide to Bird Life & Behavior. Alfred A Knopf, Inc. New York. 2001.

Tudge, Colin. The Bird. Crown Publishers. New York. 2008