ID: Little green bird: Kinglet or Vireo?

Ruby-crowned Kinglet, Hagg Lake, Washington Co., Oregon on 17 December, 2010 by Greg Gillson.

 

Last week I was up at Hagg Lake scouting for the Forest Grove Christmas Bird Count to be held the next day. A mixed feeding flock was here and I began photographing some of the more than one-dozen species present in this loose flock of chickadees, nuthatches, wrens, kinglets, and other birds.

As I was photographing the fidgety Ruby-crowned Kinglet above, I changed over to a Hermit Thrush that had popped into the open briefly. Then I came back. But the little green bird was slower and more deliberate. It had changed! A Hutton's Vireo was now in my viewfinder (below).

 

Hutton's Vireo, Hagg Lake, Washington Co., Oregon on 17 December 2010 by Greg Gillson.

 

Besides the differences from hyperactive kinglet to lethargic vireo, can you see the differences in the two birds? This is an intermediate identification challenge--not easy, but not very difficult--if you know where to look.

Both birds are greenish with broken eyerings and two white wingbars. And they are tiny--4 and 1/4 to 5 inches long from the tip of the bill to the end of the tail.

Compare the two photos above as you look for the following field marks...

1. On the Ruby-crowned Kinglet note the eyering is broken above and below. The Hutton's Vireo has the eyering missing only above the eye.
   
2. Notice that there is a blackish band on the base of the secondary feathers of the kinglet, below the lower wingbar. These feathers are edged green on the vireo.
   
3. The kinglet has a thin bill. The bill of the vireo is thicker and hooked at the tip.
   

These are all legitimate field marks. But there is a more obvious field mark to separate these similar-plumaged birds.

Compare the following two photographs...

 

Ruby-crowned Kinglet, Jackson Bottom Wetlands, Hillsboro, Oregon on 15 November 2010 by Greg Gillson.

 

Note the toothpick-thin black legs and yellow feet on the Ruby-crowned Kinglet above.

Compare that with the thick blue-gray legs and feet of the Hutton's Vireo below.

If you need to, go back and compare the legs and feet of the upper set of photos again.

Sometimes the yellow feet of the kinglet is more restricted to the pads on the bottom of the feet. Both Ruby-crowned and Golden-crowned Kinglets show this feature.

 

Hutton's Vireo, near Timber, Oregon on 22 November 2007 by Greg Gillson.

 

Finally, below is another photo of Ruby-crowned Kinglet--this time a male displaying his red crown feathers. But note the legs and feet, the black bar across the secondaries below the white wingbar, the bill, the eyering.

Now you are ready for this identification challenge!

 

Ruby-crowned Kinglet, Hagg Lake, Oregon on 29 December 2006 by Greg Gillson.