Ruby-crowned Kinglet vs. Hutton’s Vireo

Click here for part two of this post – “Bird Quiz #2: Ruby-crowned Kinglet vs. Hutton’s Vireo” – where you can put the pointers below to the test!

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Ahh, winter is here! The air is crisp, the day is short, and the rain is coming down. But rain isn’t the only thing dripping from the trees this season – Ruby-crowned Kinglets have invaded Sonoma County!
 
Breeding mostly in the far northern parts of North America, Ruby-crowned Kinglets move to the lower reaches of the United States during winter, including Northern California. This is great, as they are energetic and charming little birds, constantly flitting around in the trees like a child on Christmas morning opening present after present.
 
However, their invasion creates a bit of an ID challenge as, on first glance, they look darn near identical to Hutton’s Vireos who reside in Sonoma County year-round. Now that we’re in winter, you might be left scratching your head, wondering which of these two adorable birds you’re looking at.
 
Fear not! Upon closer inspection, there are several clues that can help us figure it out.

Vocalizations

 
The most obvious and often quickest giveaway is the difference in their calls.
 
The Ruby-crowned Kinglet vocalizes quite often, letting loose with a series of chits and chi-chits, sounding like someone churning out pages on a typewriter. During winter, this call is a common sound most everywhere – from suburban parks to deep wooded areas.

The Hutton’s Vireo gives a wheezy, whiny, fairly harsh scold call that usually ascends, sometimes ending with a stutter.

However, if you don’t hear any vocalizations, there are several other clues to look for to help with the ID.

Legs

 
Ruby-crowned Kinglets have skinny, dark brown or black legs with yellow feet  – the yellow often more visible on the soles.
 
Hutton’s Vireos have relatively thick legs that are bluish-gray all the way through the feet, resulting in a lack of contrast between leg and feet color.

Feet and leg coloring may seem like too small a feature to notice, but the two-tone effect created by the Ruby-crowned Kinglet’s yellow feet is often apparent, especially when viewing the bird from underneath as so often happens in the field.

Wing Pattern

 
Both birds typically show two white wing-bars, but noticing where the darkest part of the wing is in relation to the wing-bars is key.
 
Ruby-crowned Kinglets have a conspicuous black mark trailing the second, thicker wing-bar. The first wing-bar is thinner and shorter, and sometimes even completely obscured by the scapulars.
 
Hutton’s Vireos do not show a black mark after the second wing-bar. Instead, the darkest part of the wing is between the two wing-bars – often dark gray, and not quite black.

Bill

 
Ruby-crowned Kinglets have a tiny, sharp, black bill.
 
Hutton’s Vireos have a relatively thicker and heavier bill with a small hook at the end (which is a feature of most vireo bills). Comparatively, the bill is also more pale – typically grayish. Sometimes the lower mandible (bottom of bill) can show a pale pinkish color, as in the photo above. The photo below shows a more uniformly gray bill.

Face Pattern

 
Though both birds show a broken white eye-ring, there is a facial feature of the Hutton’s Vireo which is noticeable – its pale lores. The lore is the area between the eye and the base of the bill. A Hutton’s Vireo’s lores are paler than the rest of its face, creating a softer, more wide-eyed facial expression. The Ruby-crowned Kinglet’s lores are generally the same color as the rest of its face.

Overall Size

 
Size is very difficult to judge, especially when looking at a single bird. However, Hutton’s Vireos are substantially stockier and heavier than Ruby-crowned Kinglets. Though both species are nearly the same length, Hutton’s Vireos (ranging from 9-15 grams) can be up to three times the weight of a Ruby-crowned Kinglet (ranging from 5-10 grams). This weight difference is most apparent in the neck and head areas of a Hutton’s Vireo. With repeated exposure to both species, the heavier impression of a Hutton’s Vireo is something that can be picked up on in the field.

Behavior

 
These two birds have different foraging styles. Ruby-crowned Kinglets are constantly on the move, acrobatically maneuvering through leaves and branches. They incessantly flick their wings, and rarely sit still for more than a split-second.
 
Hutton’s Vireos are slower and more methodical when foraging, and will every so often stop on a branch to take a look around.
 
Though certainly not foolproof, we’ve found that we usually get an initial vibe from simply noticing the behavior, speed, and wing-flicking of a particular bird. We then try to home in on some of the above field marks (legs, wing pattern, bill, face pattern, overall size) to help figure out if our initial impression was correct or not.
 
And, if we’re lucky, sometimes the bird vocalizes and just gives itself away.
 
Click here for our follow-up post – “Bird Quiz #2: Ruby-crowned Kinglet vs. Hutton’s Vireo” – where you can put these pointers to the test!