Thick-billed Fox Sparrow
Encyclopedia
The Thick-billed Fox Sparrow (Passerella (iliaca) megarhyncha) group comprises the peculiarly large-billed Sierra Nevadan taxa in the genus
Passerella. It is currently classified as a "subspecies group"
within the Fox Sparrow
pending wider-spread acceptance of its species status.
These birds were long considered members of the Slate-colored Fox Sparrow
group due to morphological
characteristics (Swarth 1920), but according to mtDNA cytochrome b
sequence
and haplotype
data (Zink 1994), it forms a recognizable clade
. Research on suspected (Rising & Beadle 1996) hybridization and considering additional DNA sequence data led to confirmation of their distinctiveness (Zink & Kessen 1999); this group appears to be most closely related to the Sooty
and/or Slate-colored Fox Sparrow
s (Zink 1996, Zink & Weckstein 2003).
Thick-billed Fox Sparrows are almost identical in plumage to Slate-colored Fox Sparrow
s but have a more extensive blue-gray hood and a less rusty tail. The most striking feature of this bird is its enormous beak which can appear to be three times as large as that of the markedly small-billed Slate-colored Fox Sparrows
A Thick-billed Fox Sparrow's beak also differs in color from that of the Slate-colored. Although the culmens of both groups are grayish brown, Slate-coloreds have yellow lower mandibles instead of the steel blue of the Thick-billeds' (Rising & Beadle 1996).
to southern California
east to the Sierra Nevada and shows little geographic variation. It interbreeds with the Slate-colored complex along a narrow contact zone from southern Oregon to western Nevada
(Rising & Beadle 1996) but as noted above, gene flow
is quite limited. Sibley (2000) indicates that this group has the most diagnostic call note, "a high, flat squeak (sic) teep like California Towhee
".
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Passerella. It is currently classified as a "subspecies group"
within the Fox Sparrow
Fox Sparrow
The Fox Sparrow is a large American sparrow. It is the only member of the genus Passerella, although some authors split the genus into four species .-Taxonomy:...
pending wider-spread acceptance of its species status.
These birds were long considered members of the Slate-colored Fox Sparrow
Slate-colored Fox Sparrow
The Slate-colored Fox Sparrow group comprises the Rocky Mountain taxa in the genus Passerella. It is currently classified as a "subspecies group"...
group due to morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
characteristics (Swarth 1920), but according to mtDNA cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
and haplotype
Haplotype
A haplotype in genetics is a combination of alleles at adjacent locations on the chromosome that are transmitted together...
data (Zink 1994), it forms a recognizable clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
. Research on suspected (Rising & Beadle 1996) hybridization and considering additional DNA sequence data led to confirmation of their distinctiveness (Zink & Kessen 1999); this group appears to be most closely related to the Sooty
Sooty Fox Sparrow
The Sooty Fox Sparrow contains the darkest-colored taxa in the genus Passerella. It is currently classified as a "subspecies group"within the Fox Sparrow pending wider-spread acceptance of species status...
and/or Slate-colored Fox Sparrow
Slate-colored Fox Sparrow
The Slate-colored Fox Sparrow group comprises the Rocky Mountain taxa in the genus Passerella. It is currently classified as a "subspecies group"...
s (Zink 1996, Zink & Weckstein 2003).
Thick-billed Fox Sparrows are almost identical in plumage to Slate-colored Fox Sparrow
Slate-colored Fox Sparrow
The Slate-colored Fox Sparrow group comprises the Rocky Mountain taxa in the genus Passerella. It is currently classified as a "subspecies group"...
s but have a more extensive blue-gray hood and a less rusty tail. The most striking feature of this bird is its enormous beak which can appear to be three times as large as that of the markedly small-billed Slate-colored Fox Sparrows
A Thick-billed Fox Sparrow's beak also differs in color from that of the Slate-colored. Although the culmens of both groups are grayish brown, Slate-coloreds have yellow lower mandibles instead of the steel blue of the Thick-billeds' (Rising & Beadle 1996).
Subspecies
The megarhyncha complex breeds in mountains from southern OregonOregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
to southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
east to the Sierra Nevada and shows little geographic variation. It interbreeds with the Slate-colored complex along a narrow contact zone from southern Oregon to western Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
(Rising & Beadle 1996) but as noted above, gene flow
Gene flow
In population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...
is quite limited. Sibley (2000) indicates that this group has the most diagnostic call note, "a high, flat squeak (sic) teep like California Towhee
California Towhee
The California Towhee, Melozone crissalis, is a bird of the family Emberizidae, native to the coastal regions of western Oregon and California in the United States and Baja California Sur in Mexico....
".
- megarhyncha Baird, 1858:
- Breeds from Onion Mountains and Robinson's Butte (SW Oregon) south through inland N California to Kearsarge Pass (Inyo CountyInyo County, California-National protected areas:* Death Valley National Park * Inyo National Forest * Manzanar National Historic Site-Major highways:* U.S. Route 6* U.S. Route 395* State Route 127* State Route 136* State Route 168* State Route 178...
), as well as the western flank of the Sierra Nevada in Mono CountyMono County, CaliforniaMono County is a county located in the east central portion of the U.S. state of California, to the east of the Sierra Nevada between Yosemite National Park and Nevada. As of the 2010 census, the population was 14,202, up from 12,853 at the 2000 census...
. Winters in C and S California and adjacent MexicoMexicoThe United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
.(Weckstein et al. 2002) - More large-billed, duller, and grayer than schistacea Slate-colored Fox Sparrows; intermediate between the very large long-tailed stephensi and the more schistacea-like monoensis of this group; intergrades with former.(Weckstein et al. 2002)
- stephensi Anthony, 1895:
- Breeds in areas of the S Sierra Nevada such as Fresno and Tulare Counties, Mount PinosMount PinosMount Pinos is a mountain located in the Los Padres National Forest on the boundary between Ventura and Kern counties in California. The summit is the highest point in Ventura County.- Geography :...
and San GabrielSan Gabriel MountainsThe San Gabriel Mountains Range is located in northern Los Angeles County and western San Bernardino County, California, United States. The mountain range lies between the Los Angeles Basin and the Mojave Desert, with Interstate 5 to the west and Interstate 15 to the east...
, San BernardinoSan Bernardino MountainsThe San Bernardino Mountains are a short transverse mountain range north and east of San Bernardino in Southern California in the United States. The mountains run for approximately 60 miles east-west on the southern edge of the Mojave Desert in southwestern San Bernardino County, north of the...
, and San Jacinto MountainsSan Jacinto MountainsThe San Jacinto Mountains are a mountain range east of Los Angeles in southern California in the United States. The mountains are named for Saint Hyacinth . The Pacific Crest Trail runs along the spine of the range.The range extends for approximately from the San Bernardino Mountains southeast to...
, California, to the Sierra San Mártir, N Baja CaliforniaBaja CaliforniaBaja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
. In winter, migrates to lower elevations but generally does not migrate long distances.(Weckstein et al. 2002) - The largest, most massive-billed and longest-tailed fox sparrow; also very grey in coloration (Swarth 1920). Intergrades with megarhyncha (Weckstein et al. 2002).
- monoensis GrinnellJoseph GrinnellJoseph Grinnell was a field biologist and zoologist. He made extensive studies of the fauna of California, and is credited with introducing a method of recording precise field observations known as the Grinnell System...
& Storer, 1917:
- Breeds on the eastern flank of the Sierra Nevada in Mono County, California, and in the Walker River Range in adjacent Mineral County, NevadaMineral County, NevadaMineral County is a county located in the U.S. state of Nevada. As of the 2000 census, the population was 5,071. In 2009, it was estimated to have dropped to 4,662. Its county seat is Hawthorne.-History:...
. Winters from inland central California coastwards and south into Mexico.(Weckstein et al. 2002) - Somewhat intermediate between megarhyncha and schistacea Slate-colored Fox Sparrows, with a paler, ashy grey back.(Weckstein et al. 2002)
- brevicauda Mailliard, 1918:
- Breeds in the Mendocino RangeMendocino RangeThe Mendocino Range is one of several coastal mountain ranges which compose the Pacific Coast Range. This massive range of coastal mountains was formed during a period of coastal orogeny, millions of years ago. The Mendocino Range is a component of the California Coast Ranges of California...
of California, from the Yolla Bolly Mountains south to Snow Mountain and Sanhedrin Mountains. Migrates coastwards and south in winter.(Weckstein et al. 2002) - Similar to stephensi, but recognizable by more rusty tinge to brownish areas and the conspicuously shorter tail (Weckstein et al. 2002).
- fulva Swarth, 1918:
- Mountaineous regions from C Oregon east of Cascades Range (Steens MountainSteens MountainSteens Mountain is a large fault-block mountain in the southeastern part of the U.S. state of Oregon. Located in Harney County, it stretches some and rises from an elevation of about above the Alvord Desert to its peak at...
, Sisters and Keeno Mountains) to Modoc and Lassen Counties, California. Winters in southwesternmost California and adjacent Mexico. - A browner version of monoensis; in winter range, distinguished from olivacea Slate-colored Fox Sparrows by decidedly ruddy brown and larger bill (Weckstein et al. 2002).
- mariposae Swarth, 1918:
- Breeding in a limited area in California between the headwaters of the Little Shasta River (Siskiyou County) to Yosemite National ParkYosemite National ParkYosemite National Park is a United States National Park spanning eastern portions of Tuolumne, Mariposa and Madera counties in east central California, United States. The park covers an area of and reaches across the western slopes of the Sierra Nevada mountain chain...
and Kearsarge Pass. Winter range undocumented (Weckstein et al. 2002) due to lack of distinctiveness but probably same as megarhyncha and monoensis. - Probably nothing more than intergrades between megarhyncha and monoensis; nowadays usually synonymSynonymSynonyms are different words with almost identical or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn and onoma . The words car and automobile are synonyms...
ized with the former (Rising & Beadle 1996).