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BNA subspecies and systematics re; BARS discussion

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  • Kim M Potter
    Systematics Geographic Variation For species as a whole, slight clinal differences in size (mainly wing length and tail length), coloration of underparts, and
    Message 1 of 1 , Oct 14 7:23 AM
      Systematics
      Geographic Variation


      For species as a whole, slight clinal differences in size (mainly wing
      length and tail length), coloration of underparts, and width and pattern of
      breast-band. Coloration of underparts (adults in fresh plumage) varies from
      whitish to deep red-brown or rufous-chestnut; individual variation in this
      character is great in some populations, however, even when differences due
      to age and wear are taken into account. Completeness of dark breast-collar
      varies from broad (not invaded by color of throat) and complete to narrow
      or broken in center of breast.


      Within North America, tail length increases clinally from south to north (
      Patterson 1981; see Measurements: linear, below); otherwise no geographic
      variation documented in linear measurements or plumage coloration for North
      America (but see discussion of H. r. erythrogaster under Subspecies,
      below). Variation among Eurasian populations is summarized by Vaurie (1959)
      and Cramp (1988), who noted cline of decreasing size from west to east both
      within Europe and between European and e. Asian populations; also generally
      decreasing in size from north to south. Geographic variation of tail length
      in European populations of H. r. rustica reported by Møller (1995).


      Subspecies


      At least 6 subspecies recognized (Vaurie 1959, Phillips 1986, Cramp 1988).
      Only 1 subspecies breeds in the Americas (H. r. erythrogaster), and 2
      others are rare visitors here (H. r. rustica and H. r. gutturalis). Am.
      Ornithol. Union (1998) divided subspecies into 2 groups, placing those
      breeding in the Old World under rustica group (5 subspecies: nominate
      rustica, transitiva, savignii, tytleri, and gutturalis) separate from North
      American erythrogaster group (1 subspecies: erythrogaster). Taxonomic
      status of several populations sometimes recognized as subspecies needs
      study—e.g., breeders on Gulf Coast islands (“ insularis ”) and in extreme
      ne. Asia (“ saturata ”); also, breeding birds in South America are presumed
      to be erythrogaster, although their taxonomic status should perhaps be
      critically evaluated. Relationships among Old World and New World taxa
      needs study. For example, the e. Asian races (gutturalis and tytleri) show
      similarities to North American erythrogaster in pattern of breast-band and
      to some degree in underparts coloration, whereas the 3 races to the west in
      Eurasia and n. Africa (nominate rustica, transitiva, and savignii) are more
      similar to each other in breast-band pattern; areas of intergradation are
      found between all Eurasian subspecies, however. Comparison of mitochondrial
      DNA (mtDNA) restriction fragment profiles between Barn Swallows from ne.
      Asia and North America found a level of genetic differentiation that
      suggests a close relationship but one possibly worthy of species-level
      distinction (Zink et al. 1995). No conclusions regarding relationship
      between birds of these regions or among other taxa of Barn Swallow are
      possible, however, until samples from other parts of the species’ range are
      analyzed.


      H. r. erythrogaster Boddaert, 1783: Breeds in North America and
      occasionally in South America; winters in the Americas as described in
      Distribution, above. Distinguished from nominate rustica of Eurasia by
      breast-band normally thin, often interrupted medially (bluish black
      restricted to sides of chest and usually limited there), and underparts
      usually dark chestnut or rufous (see Distinguishing characteristics,
      above). Birds breeding on islands off n. Gulf Coast were named H. r.
      insularis by Burleigh (1942), who described them as having upperparts of
      Juvenal plumage dark brown (with hue near olive-brown rather than black),
      rear of head lacking blue-black, and adults having paler underparts
      (similar in some respects to nominate rustica). This race was not
      recognized by Am. Ornithol. Union (1957) and was listed only provisionally
      by Phillips (1986). Because juveniles and worn adults are paler on the
      underparts, assessment of this character needs to be made with care (Samuel
      1971b, Patterson 1981); critical evaluation of upperparts coloration in
      juveniles needed. Also included under erythrogaster as a synonym is H. r.
      palmeri Grinnell, 1902, named from birds taken on Amaknak I., AK.


      H. r. rustica Linnaeus, 1758: Breeds from w. Eurasia east to Yenisey Basin
      south to nw. Africa and s.-central Asia; winters mainly in sub-Saharan
      Africa; accidental in Alaska and s. Greenland. Continuous, broad,
      bluish-black breast-band contrasts with maroon throat and (in adults) pale
      breast and belly varying from pale buff or whitish to dull pinkish.


      H. r. transitiva Hartert, 1910: Breeds in s. Syria, Lebanon, nw. Jordan,
      and n. and central Israel; partially migratory, some apparently wintering
      in ne. Africa (reports southward doubted by Clancey 1970). Similar to
      nominate rustica, but breast and belly of adults darker, more consistently
      reddish buff; averages slightly larger than nominate rustica in wing (male
      125 versus 123 mm) and tail (102 ver-sus 103 mm), but there is broad
      overlap in range of measurements (Shirihai 1996). Many intermediates
      between this and nominate rustica occur, and this race is intermediate to
      savignii (see below).


      H. r. savignii Stephens, 1817: Resident in ne. Africa in Egypt (e.g., Nile
      Delta). Underparts dark maroon or rufous-chestnut, except for blue-black
      breast-band; averages slightly smaller than nominate rustica and transitiva
      (male wing averages 120 mm, tail 93 mm; Shirihai 1996).


      H. r. tytleri Jerdon, 1864: Breeds from central Siberia south to n.
      Mongolia; winters in se. Asia. Underparts rufous to red-brown, with
      breast-band narrowed and sometimes broken by maroon color of throat.


      H. r. gutturalis Scopoli, 1786: Breeds east of nominate rustica and south
      of tytleri from central Mongolia, middle Amur Basin, Korea, Kuril Is.,
      Sakhalin, some of Japanese islands south to Philippine Is. and China,
      India, and Malaysia, wintering in se. Asia, islands of n. Australia, and
      parts of e. and s. Africa (Clancey 1970); accidental or casual in w.
      Alaska, Queen Charlotte Is. (British Columbia), and nw. Hawaiian Is. (Kure
      Atoll and Midway I.; Phillips 1986). Underparts pale as in nominate rustica
      , but breast-band broken or narrowly complete. Birds with highly variable
      underparts from ne. Asia sometimes given name H. r. saturata Ridgway, 1883,
      but these included under gutturalis by Cramp (1988). Some “ saturata ”
      closely resemble erythrogaster, and this was used by Dement’ev and Gladkov
      (1968) to merge “ saturata ” under erythrogaster, a decision not followed
      by Am. Ornithol. Union (1957) or Cramp (1988).


      Kim M. Potter
      Wildlife Technician
      White River National Forest
      (970) 625-6860
      kmpotter@...
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