Wednesday, November 7, 2012

Beaks, Butts, and Bird Behavior

Lesser Goldfinch
Lately my yard has been full of little yellow birds. The Goldfinches I am familiar with, but what happens when your yard is suddenly infiltrated by other little yellow birds? This happened to me recently and suddenly I found myself with a fun birding challenge! The bird above is a Lesser Goldfinch and is a daily yard bird for me here in Tucson.
Tennessee Warbler in my Tucson yard 10-22-2012
Last month I had a new yellow bird show up in my yard. I knew it was a warbler because of the way it behaved and the shape of its beak. While a goldfinch has a stubby cone-shaped beak for eating seeds, a warbler has a thin pointy beak for eating insects. The warbler also has a totally different posture than the Goldfinch. While a goldfinch sits more upright on a branch, the warbler has a more horizontal posture as it looks for insects beneath the leaves. When I saw this yellow-greenish-gray warbler in my yard with a hint of an eye line and no wing bars, I thought at first that it was an orange-crowned warbler, which is a species commonly seen here in Arizona. However, as I did further research I discovered it was NOT and Orange-crowned warbler, but a far out of range Tennessee Warbler! How did I know this? Well, this is where the "butts" come into play. If you look at this photo you will see that the feathers underneath the bird's tail are white and not yellow. These Feathers are called "under tail coverts" and are a key field mark in identifying some species of birds. I learned that Tennessee Warblers look very similar to Orange-crowned Warblers except for their WHITE and not yellow under tail coverts. 
Orange-crowned warbler in my Tucson yard 10-23-2012
However, the next day an Orange-crowned Warbler DID show up in my yard! Here you can see its thin pointy bill and its yellow undertail coverts. Another distintion was the way the orange-crowned warbler behaved. it was much more active and flitted around the yard making a "tisk" sound like a yellow-rumped warbler does. I first heard this bird, then went outside expecting to see something different and I did!
Orange-crowned Warbler in wild Tobacco Bush
Here is the Orange-crowned warbler before it popped up in the open. While you see its yellow undertail coverts how do we know it is not a Lesser Goldfinch, which also has yellow undertail coverts? Because a Lesser Goldfinch also has a notched tail.
Orange-crowned Warbler
Compare the thin pointy beak of the Orange-crowned Warbler above with the thicker beak and the notched tail of the Lesser Goldfinch below.
Lesser Goldfinch in my Tucson Yard
Now, if you live in a part of the country that has both lesser Goldfinches and American Goldfinches, how do you tell them apart? Once again it is the color of the undertail coverts. When goldfinches are in full breeding plumage it is a bit easier to tell the males apart, but the females and the winter plumage can be a challenge. One thing that stays consistent, however, it the color of the undertail coverts. In the lesser they are yellow, while in the American they are white!
American Goldfinch, Andover, MA April 2012
Here is a female American Goldfinch with white undertail coverts!
American Goldfinch, Andover, MA  April 2012
This male American Goldfinch is molting into his breeding plumage. Notice his bright white undertail coverts!
Yellow-rumped Warbler (Audubon's) Tubac, AZ 2009
Then, on October 30 I had another bird in my yard that was different  I first noticed it because of its behavior. It was flitting around on my small piece of lawn acting like a flycatcher. I knew it was not a sparrow or a goldfinch because of its behavior. I suspected it might be a yellow-rumped warbler because of its behavior! A quick look through my binoculars proved that it was indeed a Yellow-rumped warbler! I was so excited because this now made three warblers for my new Tucson Yard Life List! Notice that this yellow-rumped warbler has streaky side, yellow flanks, a broken eye ring and a yellow spot right above its tail. This is where this species gets its name and it is one of only a few warblers that has a yellow rump.
Yellow-rumped Warbler, Tubac, AZ 2009
Yellow-rumps are also affectionately known as "butter-butts" due to this field mark. Yellow rumps are divided into two distinct sub-species. there is the Western "Audubon's" variety and the Eastern "Myrtle" population. To distinguish these two varieties you do not have to look under their tails however...
Yellow-rumped Warbler (Myrtle) Andover, MA October 2011
All you need to do is look at their throats! Myrtles have white throats while Audubon's Yellow-rumped warblers have yellow throats as well! Birding is Fun because we can learn how to identify species by the shape of the bird's beak, the color of its under tail coverts and the bird's behavior! Beaks, Butts and Behavior, they are all part of birding and Birding is Fun!
The End!
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  1. Great info! I have a lot to learn about birds and id'ing birds in the field. This is very helpful. Thanks!

  2. Very nice post and shots Kathie, some nice yard birds

    1. Dan, they were a surprise! I did not expect to get these warblers in my suburban yard in Tucson!

  3. Warbler city! They are fun to ID. Somehow they seem easier to me to ID than sparrows! You really have made a nice sunny spot and attractive area for birds:)

  4. HI Katie...I loved this ...there are times when it is not easy to ID a bird that is similar and only bits and pieces to go by!!
    I like how you compared these!!
    Nice you got the Yellow Rump...I have had one around for awhile, I do hope he knows when to leave for warmer parts!!
    Great shot's!

    1. Grammie, thanks! And I am sure the warbler will know when to leave! They are such cuties and beauties!

  5. more of the 'birds with yellow' I love them. Surely the American Goldfinch is some relative of the canary?

    1. Carole, I don't know! Good question! They certainly have the color!

  6. I like the term "butter butt"! I hadn't heard that before, but I'm sure I'll think of it next time I see a Yellow-rumped Warbler! Great info on the differences of these similar species.

    1. Tammy, I had the same reaction when I learned the term and now it is the first thing I think of when I see them!

  7. Terrific post filled with excellent bird identification information and beautiful photographs! How exciting for you to be able to add three new warblers to your Tuscon Yard List! All the birds are so very lovely.

  8. Congrats on your new yard birds! Great collection of birds and photos, Kathie!

  9. Just catching up, very informative post, Kathie, and fun too! I envy you your yard list, so much variety whereas here I have to be content with Chickadees mostly.