Wednesday, December 18, 2013

Warbler Guy, can you give me a quick way to tell Myrtle from Audubon’s Yellow-rumped Warbler during the winter (non-breeding season)? I see both subspecies of Yellow-rumps where I live in the winter (SF Bay Area), so knowing how to tell Yellow-rumped Warbler subspecies apart would probably be a good idea.

Jay, in San Francisco, there’s two field marks that are excellent, diagnostic clues to help you identify both of these subspecies apart from one another (see drawings, below).

Let's sort out the "winter" plumages here only, given the obvious differences in appearance for breeding season individuals of both subspecies. 

Most (but NOT all) Audubon’s adults during the "winter" wear a faint to solid yellow throat and the Myrtle always possesses a white throat. In all age classes — from hatch year to definitive adults — a Myrtle never shows a white throat. That’s the easy, brief answer.

(Above drawing courtesy of National Geographic.)

But it’s not the full one. That’s because rare to occasional individuals of Audubon's ALSO may express a white throat. Which means it's possible to view a white-throated Yellow-rumped Warbler that could be EITHER the Myrtle or Audubon's subspecies.

So now what do you do for ID?

Use the absence of a faint supercilum (i.e., eyebrow) to identify Audubon’s (see drawing here) during the non-breeding "winter" season. Noticing the lack of this feature on a Yellow-rumped Warbler with a white throat should move you to say: “Bingo, it’s an Audubon’s" (i.e., Audubon's are said to wear a "plain face.)

However, if you see during the non-breeding season both a faint white supercilum mark and a white throat that reaches around toward the middle and mid-back region of the neck area on both sides of the head, then it’s a Myrtle.

In sum, Myrtle Yellow-rumped Warbler shows a faint white supercilum and a greater amount of white throat surface area than the Audubon’s subspecies that has a more plain face (lacking the white supercilium mark) and a smaller white to, more typically, faint to dark yellow throat.

The definitive source for my judgment in this matter consistently remains the Identification Guide to North American Bird, Part 1, by Peter Pyle (Slate Creek Press), which is the bird bander's guide to identification of birds "in the hand," and features field mark information corresponding to all age classes of songbirds.

Tuesday, December 10, 2013

Warbler Guy, I'm coming to California birding tour soon, so where do I check for "rare" bird alerts? Do you remember leading me as a birding guide when we went to Point Reyes National Seashore?

Hi Davey....and, "yes," I remember you from our birding tour in 2012.

Answer to your question, above: You can check:

....with this site a composite list featuring all the listserv sites in California.

Click on one or more as you please to see the latest bird sightings lists posted by


Glad to help:

Happy Holidays and, remember, only ~45 days until our first neotropical migrant
returns to the SF Bay Area for the nesting season:
Allen's Hummingbird

Darn, though: Orange-crowned Warbler returnees are still ~50 to 60 days from appearing after migrating here.

Sunday, December 1, 2013

Warbler Guy, which app for iPhone & my phone, an Android, works to see Ebird sightings? Can I see where to go for Ebird sightings by using a bird app?

Carly, in Portland:

I've pasted the best app I know as the solution to your questions, above.

Though I don't remember the price I paid for Birdseye, it's an app I utilize frequently.

Any time I wish to know where the latest-greatest bird sightings have been in my area (or to any area that I travel, near or far), I look at Birdseye on my iPhone 5.

Happy Holidays, Daniel

415-382-1827 (SF Bay Area)