Wednesday, October 14, 2015

Is it possible to distinguish the call notes of Audubon’s vs. Myrtle Yellow-rumped Warbler during the non-breeding season where they occur together?

Answer:


Seeing is believing when identifying (patiently!) an Audubon’s vs. Myrtle Yellow-Rumped Warbler.

But sometimes you only hear an obvious Yellow-rumped Warbler chip note.

At least I do.

Then, the Mind Game is to ask myself: Is that an Audubon’s or Myrtle subspecies within the species of Yellow-rumped?

Difficult decision (!)

And consider your antenna first-rate, premium, high-octane — if you can tell the difference between these two call notes and confidently exclaim: “That’s an Audubon’s” (Or “Eureka, trust me: that’s a Myrtle chip note.”



(Above: An Audubon's Yellow-rumped Warbler subspecies (in breeding plumage) appears in the top photo. A non-breeding view of a Myrtle Yellow-rumped Warbler subspecies is below the Audubons'.)

*

Why do you need to tell one chip note vs. the other to know if it’s an Audubon’s vs. a Myrtle?

Because, of course, most Yellow-rumpeds are NOT singing during the non-breeding season, but you do often hear their loud chip or call notes from October – April when they’re in my area (San Francisco Bay Area where I am a Birding Guide in Marin County).

In many cases you can hear how the Myrtle (one of the subspecies of the Yellow-rumped Warbler species) has a flatter and softer chip note than the Audubon’s.

The “ch” component of the call note is weaker for the Myrtle and it often gives many calls in rapid succession.

However, be careful. Intergrades (individuals that display visual characteristics specific to both Audubon’s and Myrtle) may announce call notes of the other subspecies. In other words, it’s possible to see a bird that looks like an Audubon’s, but it’s call note sounds like a Myrtle. This individual could likely be an intergrade.

Of course, once you hear a Yellow-rumped chip note, go find it.

Then you can truly tell the difference in the two subspecies by their appearance: In general, the Myrtle male is told by its white throat that wraps farther around toward the back of the head/nape....while the Audubon’s male has a yellow throat. Note the Myrtle often also displays a slight white supercilium or eyebrow at the front of the head, whereas the Audubon’s head is plain and gray throughout.

Questions? Let the Warbler Guy know, please: danieledelstein@att.net

My web site for warbler questions, warbler information, warbler quizzes: http://warblerwatch.blogspot.com

My bird guiding in California and birding tours in California information: warblerwatch.com via the Birding Tours button at the home page.


3 comments:

Anonymous said...

You have AOK ears, W man

Halli

Anonymous said...

Thaks for the info....though I still have trouble w/ ww ID.

Mary dobson

Anonymous said...

NICE WG, DEANNA