Wednesday, November 23, 2016

Double-crested Cormorants Visit CSU Stanislaus

Double-crested Cormorant (Phalacrocorax auritus)
Recently, there have been a few newcomers on campus at CSU Stanislaus.  In addition to augmented numbers of Canada Geese (Branta Canadensis) and American Coots (Fulica americana), the cooler fall weather seems to have brought a small flock of Double-crested Cormorants (Phalacrocorax auritus) to campus ponds.  I've counted seven at one time, mixed in with a much larger flock of Canada Geese. 
The cormorants, coots, and Canada geese at Stanislaus State lend a rather cosmopolitan feel to the ponds.
Double-crested Cormorants can be found across North America, commonly in fresh water.  They sit very low in the water, sometimes with only their rather snake-like heads and necks exposed above the surface.  They have obvious bright yellow skin on their faces, and vivid blue eyes.  If you happen to get a glimpse of the inside of a Double-crested Cormorant's mouth, it is also bright blue!  Cormorants are expert divers, chasing and catching fish underwater.  If you see a cormorant dive underwater and watch for a moment... it will often pop up many yards from where it vanished beneath the surface!
Double-crested Cormorant striking a common pose: wings outstretched to dry in the sun.
Most people will first notice these bird because of their common pose, perched on a rock or other object, large wings outstretched toward the sun.  Cormorants have less preen oil than other birds (the oil that allows water to literally roll off a duck's back) and therefore must spend time letting their wings dry.  Though it may seem that a bird that sits low in the water and dives frequently ought to have superior waterproofing, scientists believe that the opposite is true, and that having less waterproof oil on their feathers allows them to dive and swim underwater with greater efficiency.
Double-crested Cormorant, sitting low in the water

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