Sunday, June 6, 2010

Eastern vs. Western Meadowlark

I naively assumed that identifying Eastern and Western Meadowlarks is not impossible.  According to my first Peterson guide, although the two meadowlarks are nearly identical, the Western is paler on the back and has the "yellow of the throat edging a trifle farther onto the cheek; best recognized by...song." The Eastern sings "two clear slurred whistles, musical and pulled out: tee-yah, tee-yair (last note 'skewy' and descending."  The Western, on the other hand, sings "a variable song of seven to ten notes, flute-like, gurgling, and double-noted; very unlike clear slurred whistles of Eastern Meadowlark."  Listen to these calls by clicking on these names: Eastern Meadowlark; Western Meadowlark.
I spent the last 30 years in South Dakota surrounded by Western Meadowlarks.  The Eastern Meadowlarks I am now seeing in Minnesota to appear to have darker backs than those South Dakota birds.  Look at the Eastern Meadowlark in the photo above (taken Thursday near Northfield, Minnesota).  The yellow of the throat does not go into the cheeks or the malar region behind the lower mandible and above the throat.  In the photo below of a Western Meadowlark from Fort Pierre, South Dakota, you can see that the throat's yellow color does invade the malar region on the sides of the face. 
Seems simple, if somewhat difficult to observe, at least for us in the upper Midwest (other races of meadowlarks from elsewhere in the United Stated complicate the situation). Enough variation exists in the yellow-on-the-face field mark (for example, see http://www.birds.cornell.edu/crows/mlarkdiff.htmhttp://www.birds.cornell.edu/crows/mlarkdiff.htm) that some rare bird committees do not accept meadowlark identifications without accompanying tapes of the calls.

But the situation gets more complicated. Meadowlarks, where their ranges overlap (as they do in Minnesota), can learn and sing each other's (and other species') calls! (See Davis, Stephen K. and Wesley E. Lanyon. 2008. Western Meadowlark (Sturnella neglecta), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu.bnaproxy.birds.cornell.edu/bna/species/104).  Furthermore, these two species occasionally hybridize.

Peter Pyle in his Identification Guide to North American Birds, a book used as an ultimate guide for banders, writes "this is one of the most difficult in-hand species identification problems."  According to Pyle, the complete lack of yellow in the malar region identifies female Eastern Meadowlarks, and extensively yellow ones indicate male Weaterns. What is a birder to do?  The answer must be to proceed VERY carefully when identifying meadowlarks!

3 comments:

  1. Dan - I've been to Afton SP several times this year. Their eastern meadowlarks have some kind of "alternate" call that I didn't figure out for a while. Maybe other eastern meadowlarks do this too but I don't remember hearing it before. At least the ones at Afton do it a lot.
    I've been listening at other areas this year that have eastern meadowlarks (Randolph Industrial Park) and have not heard the call.
    Cheers
    Larry S

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  2. Hi Dan. Thank you for the great info. I believe I knew you at LSU. 1976-79? If so, I was in several grad courses with you. I am currently teaching high school science and developing a scientific area in southwestern Wisconsin.
    Get back to me,
    Roger B

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  3. Hi Roger. Please send me your e-mail. Dan

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