Tuesday, September 18, 2018

Double-Crested Cormorant - Nominate Subspecies

There are five subspecies of the double-crested cormorant (Phalacrocorax auritus) and I've now seen at least three of them, although I've never seen them when the crests are present (when they are breeding). 

First, the Farallon cormorant (P. a. albociliatus), which I've seen, is found from Vancouver Island down to the Gulf of California and inland in Washington, Oregon, California, Nevada and Arizona. It is a slightly paler grayish/bronze on the mantle and upperwing from the nominate subspecies. Its long crest, during breeding season, shows variable white. 

Second, the Florida cormorant (P. a. floridanus), which I've seen, is found from Texas - east and North Carolina - south, to Florida, down to Cuba and the Yucatan Peninsula. It is now common only in Florida and is the smallest subspecies. It has dark crests. 

The nominate subspecies (P. a. auritus), which I recently saw, does not have a common name I can find, other than perhaps "the" double-crested cormorant. It is moderately large and has black crests. It has the largest range, from Eastern Canada (the Gulf of St. Lawrence) down to Cape Cod, then west to the Great Basin, including Utah. My pictures below are of this nominate subspecies. 

The white-crested cormorant (P. a. cincinnatus) is found on the southern coast of Alaska and the Aleutian Islands. It is the largest of the subspecies and has straight white crests. I probably saw this subspecies in Alaska on the Kenai Peninsula but have no photos to document it.  

The last subspecies (P. a. heuretus), also apparently without a common name, another smaller subspecies, has straight white crests and is found in the Bahamas in the lakes of San Salvador. 

We recently visited some rock islands off the coast of Cape Breton, Nova Scotia, and they were literally over-run with the nominate subspecies, the double-crested cormorant. We found them in large groups, both standing and floating in the water, with an occasional great cormorant or great black-backed gull among them. 
From a distance you can see the cormorants grouped together on a patch of white (guano). 
Swimming together below the patch of white. 
Lined up along a rock strip.
The orange facial color is what really makes them stand out. 

1 comment:

  1. Love that last photo.You know, it's not too late to go back and get a zoology degree. Well, actually, maybe it is.