{"id":2675,"date":"2011-01-22T11:45:41","date_gmt":"2011-01-22T17:45:41","guid":{"rendered":"http:\/\/earbirding.com\/blog\/?p=2675"},"modified":"2016-11-25T08:24:16","modified_gmt":"2016-11-25T14:24:16","slug":"splitting-mountain-chickadee","status":"publish","type":"post","link":"http:\/\/earbirding.com\/blog\/archives\/2675","title":{"rendered":"Splitting Mountain Chickadee"},"content":{"rendered":"

The AOU’s North American Checklist Committee has posted a set of proposals<\/a> currently under consideration.\u00a0 The biggest surprise is a proposed split of Mountain Chickadee into two new species:<\/p>\n

    \n
  1. Gambel\u2019s Chickadee<\/strong> (Poecile gambeli<\/em>) in the Rocky Mountains and the Great Basin, including populations in eastern Washington and Oregon;<\/li>\n
  2. Bailey\u2019s Chickadee<\/strong> (Poecile baileyae<\/em>) in the Sierra Nevada, the Cascades, and the California coastal mountains.<\/li>\n<\/ol>\n

    Until the AOU proposal appeared, a potential split of Mountain Chickadee was not even on my radar screen.\u00a0 However, two different molecular studies have found evidence that the two groups of chickadees are genetically quite distinct, and they apparently differ slightly in appearance, with “Gambel’s” Chickadees having a slightly longer tail, slightly more white above the eyes, and a faint buffy tinge to the underparts and back.<\/p>\n\n\n\n\t\n\t\t\n\t\t
    \"\"<\/a><\/td>\"\"<\/a><\/td>\n\t<\/tr>\n\t
    \"Gambel's\" Mountain Chickadee, Sandia Crest, NM, 3\/26\/2008. Note the buffy underparts and broad eyestripe. Photo by J.N. Stuart<\/a> (Creative Commons 2.0).<\/td>\"Bailey's\" Mountain Chickadee, Yosemite National Park, CA, 11\/24\/2007. Note the gray underparts and narrow eyestripe. Photo by Yathin<\/a> (Creative Commons 2.0).<\/td>\n\t<\/tr>\n<\/tbody>\n<\/table>\n\n

    In addition, the proposal mentions song differences.\u00a0 Sadly, it provides scant evidence for this claim.\u00a0 Here’s the entire discussion of vocalizations:<\/p>\n

    Miller (1934:163) reported on song differences that he detected between Mountain Chickadees from southern Utah (wasatchensis<\/em>) and from California (abbreviatus <\/em>or baileyae<\/em>): \u201cI note repeatedly that the songs of this chickadee [wasatchensis<\/em>] consists of two groups of notes separated by three or more half tones of pitch. In contrast to this type of song are those of the races P. g. baileyae<\/em> and abbreviatus <\/em>in which the greatest interval of pitch with rare exceptions is no larger than one whole tone.\u201d<\/p><\/blockquote>\n

    This is flimsy evidence indeed.\u00a0 The difference in pitch interval that Miller noted could potentially be significant, but it’s only one metric by which to measure the complex matrix of geographic variation in Mountain Chickadee vocalizations.\u00a0 Mountain Chickadee’s vast geographic range comprises a balkanized patchwork of dozens of different dialect regions, as one would expect in a bird that learns its song.\u00a0 Miller was a single naturalist noting a single difference between just two or three of these dialects, in an era before sound recording and spectrographic analysis.<\/p>\n

    Furthermore, the evidence I’ve found so far doesn’t even corroborate his original observation.\u00a0 Here’s the most common dialect variant of “Bailey’s” Chickadee, the version of Mountain Chickadee song most likely to be heard all throughout the Sierra Nevada:<\/p>\n

    \"\"<\/a>
    "Bailey's" Mountain Chickadee song, Lava Beds National Monument, California, 5\/29\/2002. Recording by Geoff Keller (LNS 120257).<\/figcaption><\/figure>\n

    (Click here<\/a> to listen to the recording at the Macaulay Library.)<\/p>\n

    Many observers in the region transliterate this (and similar songs) as “cheese-burger,” although there’s actually a short extra note in front of the “cheese” in most parts of the Sierra.\u00a0 The “cheese” and “burger” parts of the song are separated by about a full step on average, with slight variations from place to place [1<\/a> 2<\/a> 3<\/a> 4<\/a> 5<\/a>].\u00a0 So far, so good — these recordings are mostly in line with Miller’s observations.<\/p>\n

    But the wide pitch intervals that Miller reported from southern Utah are certainly not representative of most “Gambel’s” Chickadees.\u00a0 In this Borror Lab recording<\/a> from northern Utah, the notes are quite close to one another in pitch, each about a half step lower than the last.\u00a0 And most Mountain Chickadees in Colorado sing nearly monotone songs, like in this typical example:<\/p>\n

    \"\"<\/a>
    Mountain Chickadee song, Larimer County, CO, 5\/28\/2008.<\/figcaption><\/figure>\nhttp:\/\/earbirding.com\/blog\/wp-content\/uploads\/2011\/01\/MOCHs2str-NDP2008-23-30.mp3<\/a><\/audio>\n

    Here’s an example of a “Gambel’s” Chickadee from British Columbia that sings a songtype not unlike the Sierra Nevada “Bailey’s” song:<\/p>\n

    \n