BNA subspecies and systematics re; BARS discussion
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).
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
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
White River National Forest