Pacific Loon (Gavia pacifica), Tempe Town Lake, Maricopa County

This Pacific Loon was discovered on Tempe Town Lake by Pete Moulton and Cynthia Donald on 11 January 2009 and it was photographed by Michael Moore on 12 January 2009.  This is likely the same bird that was previously at McCormick Ranch in Scottsdale (see here). The face pattern looked subtly different in the field, but the lighting is so different it is hard to compare these images with the images of the Scottsdale bird.

Pacific Loon has been regular in the Lower Colorado River Valley in recent years but elsewhere in the state it is a casual transient and winter visitor.

Although superficially similar to Common Loon, nonbreeding plumaged Pacific Loon can be identified by the straight border on the neck between the dark and the light, the dark around eye, and the diagnostic chin strap (which is not always present nor easy to see).

There are no records of the very similar Arctic Loon in Arizona.  The field mark usually cited for Arctic Loon is a white patch at the water line.  Note that this bird is showing a white patch at the water line.  However, the patch on Arctic Loon is usually further back and more triangular or wedge shaped.  Pacific Loons can show white like this so application of this field mark must be done with care.  Arctic Loon lacks the chin strap. 

12 January 2009, digiscoped photos by Michael Moore

All photos are copyrighted© by photographer

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