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.  A thick-billed fox sparrow's beak also differs in color from that of the slate-colored. 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. Better known as a winter visitor in our region, recent evidence suggests that this species is rapidly expanding its breeding range mountaintop to mountaintop, moving southwest in New Hampshire and Vermont. Most of the Fox Sparrow breeding range covers areas of northern Canada and Alaska–areas that are remote and poorly surveyed by the North American Breeding Bird Survey. , They winter in temperate and subtropical North America; in the northern United States and southern Canada they often only stop over on their migration further south. The thick-billed fox sparrow (Passerella (iliaca) megarhyncha) group comprises the peculiarly large-billed Sierra Nevadan taxa in the genus Passerella. The nature of migration in Fox Sparrows is, like nearly every other element of their natural history, variable. Volume 19/Number 2–3 30 METHODS Identification To understand the identification of the various subspecies, I review the available literature, specimens at U Davis, and contemporary photographs from the breeding grounds and well-known wintering areas. , Weckstein, Jason D.; Kroodsma, D.E. https://en.wikipedia.org/w/index.php?title=Thick-billed_fox_sparrow&oldid=977816671, Native birds of the Western United States, Taxonbars with automatically added original combinations, Creative Commons Attribution-ShareAlike License, This page was last edited on 11 September 2020, at 04:50. Individuals from different parts of its broad range differ both in size and color from individuals in other parts of the range. Most of the Fox Sparrow breeding range covers areas of northern Canada and Alaska–areas that are remote and poorly surveyed by the North American Breeding Bird Survey. Fox Sparrow are an uncommon breeding species in far northern Maine. 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. Red fox sparrows breed in a wide band that stretches through mostly taiga habitat, from Newfoundland to northern Alaska.  The Yukon fox sparrow (Passerella iliaca zaboria) differs from the nominate subspecies, the eastern fox sparrow (Passerella iliaca iliaca) only in having a grayer head and a browner malar stripe on average. It has long been suspected to be a separate evolutionary lineage due to morphological distinctness, and this is confirmed by analysis of mtDNA sequence and haplotype data. The spring migration starts around February, and by early May almost all birds have returned to the breeding grounds. The recent expansion of Fox Sparrow (Passerella iliaca iliaca) breeding range into the northeastern United States. International Bicknell's Thrush Conservation Group, eBird data for this species during June and July.  Clutch consists of 3–5 pale blue to pale green eggs that are thickly spotted with brown. The slate-colored fox sparrow (Passerella (iliaca) schistacea) group comprises the Rocky Mountain taxa in the genus Passerella.It is currently classified as a "subspecies group" within the fox sparrows pending a more-thorough genetic assay of all forms.  The eggs are mostly incubated by the female though both sexes feed the young. John Lloyd (former Director of Science for the Vermont Center for Ecostudies) analyzed eBird data for this species during June and July from the 1980s onward. In winter, the Mississippi River and the US states of Alabama and Georgia mark the approximate boundary between the subspecies' ranges. P. i. iliaca occurs from S Wisconsin and Ontario east to Massachusetts and then along the coast north to southern Canada; it ranges south to the Gulf of Mexico and N Florida, whereas P. i. zaboria occurs from SE Minnesota to the Great Plains, south to Texas and east to the zone of overlap mentioned above. Washington is likely small and diffuse, and their nests can be exceedingly difficult to locate. Figure provided by the United States Geological Survey. This bird species is native to North America and the Caribbean. Occurs as a breeding species in the Cascade Mountains of Washington and Oregon and the Sierra Nevada range of California. Large-billed Fox Sparrow. Young birds are altricial and fledge in 9 to 11 days. Figure 2 from Lloyd (2018): Fox Sparrow occurrence records in June-July from eBird checklists from 1980 through 2017. Citation for the CWHR System is as follows: California Department of Fish and Wildlife California Interagency Wildlife Task Group. In fall, they start to move south around early October, and by mid-November, only the last stragglers still remain up North. The lower bill is yellow while the top transitions from yellow at the bottom to black at the top. The breast has reddish brown streaks with a messy central spot. Fox Sparrows winter (red) throughout most of the southern half of the United States. Solid black lines above and below indicate the uncertainty around estimates of relative abundance. All inquiries are welcomed. The recent southern range expansion of Fox Sparrows into our region may be more reflective of changing habitat use and logging patterns than indicative of a species adapting to rising temperatures; see Lloyd (2018) for an excellent and thorough discussion of these points.