Double Crested Cormorant in Eastern Washington

Double-crested Cormorant (Phalacrocorax auritus)

I learned a bit about cormorants after spotting the cormorant shown above in an irrigation run off pond in eastern Washington. Cormorants are common site for anyone taking a Washington State Ferry. They often can be seen in the pose of the one pictured above with their wings outspread drying off. I was a bit surprised to see a cormorant in eastern Washington. I thought they were salt water only. But apparently Phalacrocorax auritus can be found in both fresh and salt water and has recently expanded its range up the Columbia River into the Mid Columbia River area.

The two other cormorant species, Brandt's and pelagic, can be seen in the salt water along with the double-crested. I'll have to sharpen my cormorant observation skills to distinguish between these species.

Why the range expansion by Phalacrocorax auritus? I can't answer that, but it is an interesting question. Were the birds in eastern Washington in the past and are just returning to their old range? I can say that habitat areas suitable for the birds has expanded with significantly more wetland areas as a result of irrigation water and water backed up by dams along the rivers. For example, the pond pictured above was scrub steppe land 20 years ago. 

There is also a climate consideration. Even with more habitat can these birds tolerate a periodic extremely cold winter. In this regard, it has been 30 years since the Columbia River last froze over in the Mid Colombia area. How well can Phalacrocorax auritus manage long protracted cold spells with loss of access to food sources? Or will they simply head down river to open water when conditions turn bad? Something to watch for the next time eastern Washington experiences an exceptionally long cold spell.