SPOTTED TOWHEE

Pipilo maculatus arcticus, P. m. montanus

Status: Common regular breeder west and central, rare east. Uncommon spring and fall migrant statewide. Rare regular winter visitor southeast and south, rare casual elsewhere.

Breeding

Figure 1. Proportion of “dark-backed” towhees (see text) by “zone” based on a review of eBird reports (Silcock, unpublished data).

 

Distribution by zone (see Fig 1) of phenotypic Spotted Towhees (red), intergrades resembling phenotypic Spotted Towhees (red cross hatched), and intergrades of obvious mixed heritage with dark-backed birds resembling Eastern Towhees more predominant eastward (pink cross hatched).

Migration and winter

Documentation: Specimen: UNSM ZM7252, 24 May 1900 Monroe Canyon, Sioux Co. A phenotypic intergrade specimen was collected near Lisco, Garden Co 12 Jun 2018 and deposited in the Cornell University Museum of Vertebrates.

Taxonomy: There are 19-21 subspecies currently recognized (AOU 1957, Pyle 1997, Gill et al 2022), 10-12 in Mexico and Central America. The other nine occur north of Mexico and are often divided into two groups, Coastal, including four subspecies limited in distribution to the Pacific Coast from British Columbia southward, and Interior, including five subspecies: falcinellus, resident in southern Oregon to central California, curtatus, breeding Rocky Mountains from southwestern Canada and interior northwestern USA south to northern Nevada, wintering to southern California and southern Arizona, arcticus, breeding northern Great Plains from southern Alberta and Saskatchewan south, east of the Rocky Mountains, to northeastern Wyoming, extreme  northeastern Colorado, and western Nebraska, wintering to southwest New Mexico and south Texas, montanus, breeding in the Rocky Mountains, south of curtatus and arcticus, from southwestern Wyoming through western Colorado, Arizona and New Mexico, wintering to southwest Texas, and gaigei, resident in southeast New Mexico and west Texas.

Nebraska breeding birds are arcticus (AOU 1957) but montanus is increasingly reported in summer in the southern Panhandle (below). Banding data show that subspecies arcticus and montanus migrate southeastward to winter ranges extending north and east to Kansas and extreme southeastern Nebraska (Bartos Smith and Greenlaw 2020).

There is but a single specimen record of montanus that was taken 5 Oct 1915 at North Platte, Lincoln Co; the remains were “badly decomposed” but parts were submitted to H. C. Oberholser, who confirmed that the bird was indeed montanus (Swenk 1918, Tout 1947). Subspecies montanus has been recorded in Morton Co, Kansas (Johnston 1965, AOU 1957), is at least partly migratory, and, although its breeding range is mostly west and south of Nebraska (Bartos Smith and Greenlaw 2020), it includes the Front Range of Colorado, where it is “very common” (Steven Mlodinow, personal communication). In northeastern Colorado, along the South Platte River, both arcticus and montanus have been reported, along with a large number of hybrids/intergrades, notably at Tamarack WMA in Logan Co (Steven Mlodinow, personal communication). Approximately 80% of the Colorado Spotted Towhees in Logan and Sedgwick Cos are montanus (Steven Mlodinow, personal communication) and so its occurrence in Nebraska would not be unexpected.

As a note of caution, Mlodinow (personal communication) stated: “The NE breeding SPTO have more/larger spots above and more extensive white below the tail (on folded tail, white nearly reaching tip of under tail coverts) compared with CO SPTO. Being subspecies, it is unclear how much variation each taxon would entail, so I typically only [identify] those that seem distinctive and that I can photograph. I am impressed by how much the two populations differ as a whole.”

Recently, Mlodinow found that during migration a “goodly percentage” of the Spotted Towhees at Oliver Reservoir, Kimball Co, Nebraska were montanus, including one there 13 Apr 2019, but none were found in the North Platte River Valley, where only arcticus were found in Scotts Bluff Co and at Ash Hollow SHP, Garden Co. More recently, montanus has been found in the North Platte River Valley in Scotts Bluff Co, with records 30 Jul 2019 Wildcat Hills NC, and in 2022 three at Carter Canyon 23 Jun and a juvenile montanus was photographed 13 Sep. In 2023 five in Carter Canyon 13 Jul, where the observer noted “perhaps all SPTO here are maculatus”, 13-21 Jul along Turkey Drive, two on 17 Jun at Wildcat Hills SRA, 23 Jun at Buffalo Creek WMA, and 26 Sep Gering Cemetery.

A surprisingly northerly Nebraska record was of two “maculatus group” birds on East Ash Creek, Dawes Co 14 May 2019 (Mlodinow, Remsen; numerous photos; eBird.org); likely the same two were there 15 Jun 2019.

In this account, and that of Eastern Towhee, we use the terms “spotted-backed” and “dark-backed” for the phenotypes occurring in Nebraska. As shown in Figure 1, there is considerable overlap of these two phenotypes in the state. A recent study (Silcock, unpublished data) based on reports to eBird of phenotypic Spotted and Eastern Towhees showed that >90% of towhees in the western two-thirds of the state were reported as Spotted, and >87% of the reports along the east edge of the state as Eastern, with an “overlap zone” where the two were reported in roughly equal numbers (see Figure 1). Because of the overlap of the two phenotypes, it has generally been assumed that “spotted-backed” towhees with reduced spotting that occur in the same general areas as “dark-backed” towhees with small amounts of spotting are introgressants. The studies by Sibley and West (1959) and Short (1961), which have been interpreted as showing that assortative mating retained some 56% of towhees in the overlap areas as phenotypic Spotted or Eastern Towhees, along with genetic data (Ball and Avise 1992) showing the absence of shared haplotypes in samples from western and eastern extremes of the North American range (Washington, South Carolina, Georgia), were the basis for separating the former Rufous-sided Towhee into Spotted and Eastern Towhees (Banks et al 1995, Bartos Smith and Greenlaw 2020, Greenlaw 2020). See Comments, below.

An unexpected finding was a white-eyed Spotted Towhee at Gilbert-Baker WMA, Sioux Co 21 and 28 May 2018 (Wright 2019b); Wright assumed that a pigment mutation in the stroma of the bird’s irides resulted in the lack of coloration and that such an aberration should be looked for in Spotted Towhee populations.

There are four records in eBird of hybrids between Spotted Towhee and Green-tailed Towhee, nearest one in Baca Co, Colorado (eBird.org, accessed Jul 2023).

Spring: winter <<<>>> May 22, 23, 23 (southeast); Mar 24, 25, 26 <<<>>> summer (central and northeast); Apr 9, 10, 11 <<<>>> summer (west)

Later dates in the southeast are 27 May 2023 Butler Co, 28 May 2016 Nemaha Co (heard only), 30 May 2019 Douglas Co, and 3 Jun 2024 Seward Co.

Earlier dates in the central and northeast are 3 Mar 2019 Rock Co, 15 Mar 2024 Frontier Co, 16 Mar 2020 Hitchcock Co, 17 Mar 2020 Merrick Co, 19 Mar 2024 Cherry Co, and 21 Mar 2021 Knox Co.

An earlier date in the west is 26 Mar 2020 Carter Canyon, Scotts Bluff Co.

Wintering birds in the south and east probably depart by early May, although last dates are difficult to determine due to the presence of intergrades that are often reported as this species.

• High counts: 85 at Lake Ogallala, Keith Co 30 Apr 2000, 45 at Lilley’s Sandpit, Hall Co, 9 May 1998, 42 in Hall Co 11 May 2002, and 38 at Oliver Reservoir, Kimball Co 4 May 2024.

Summer: BBS data 1966-2015 (Sauer et al 2017) show fairly even distribution within the virtually statewide range, with perhaps higher numbers in southwestern and northwestern Nebraska. BBS trend analysis (Sauer et al 2020) shows Spotted Towhees have increased 1.76% annually (95% C.I.; 0.08, 4.04) per year in Nebraska 1966-2019.

• Breeding phenology:
• Nestbuilding: 1 Jun
• Eggs: 8 May- 6 Jul (Mollhoff 2022)
  Nestlings: 8 Jun-22 Jul
  Fledglings: 7-22 Jul

• High counts: 52 at Gilbert-Baker WMA, Sioux Co 11 Jul 2022, 52 at Wildcat Hills SRA, Scotts Bluff Co 17 Jun 2023, 41 at Buffalo Creek WMA, Scotts Bluff Co 23 Jun 2023, 40 at NNF Bessey, Thomas Co 22 Jul 2023, and 37 there 6 Jun 2022.

Fall: Sep 16, 17, 19<<<>>> winter (southeast); summer <<<>>> Oct 26, 26, 26 (west)

Earlier dates in the southeast are 4 Sep 2023 Butler Co, 10 Sep 2017 Lancaster Co, 12 Sep 2014 Lancaster Co,

Most departing birds leave the summer range by mid-Oct.

Later dates in the west are 2 Nov 2021 Scotts Bluff Co, and 27 Nov 2022 Mitchell, Scotts Bluff Co.

A large total of 120 were banded in the period 24 Aug-7 Oct for the 2015 fall season at Wildcat Hills NC, Scotts Bluff Co, indicating peak fall movement occurs there in Sep. In 2023, as of 2 Sep, 48 new captures were banded (Alicia Bachman, personal communication).

Significant movement into the southeast begins in late Sep; it was “common” in Omaha in early Oct 1975 (Williams 1976). The first “spotted” birds appear in Missouri in early Oct (Robbins 2018)

• High counts: 60 near Gibbon, Buffalo Co 10 Oct 1998, 40 in northern Lancaster Co 17 Oct 1998, and 35 at Wildcat Hills NC 24 Aug 2015 (banded).

Winter: CBC data indicate that this species is still rather evenly distributed statewide in Dec, although numbers are lowest in the Panhandle and the north. By Jan, reports from the west and north are few; numbers are lowest in Feb, when most are in the southeast.

Overwintering away from the southeast is rare; two were at a Knox Co ranch through 10 Jan 2024, one surviving through 17 Feb 2024.

There are 21 winter reports Jan-Mar from the North Platte Valley, and these others from the north and west: 31 Dec 2005 Crawford CBC, 12 Jan 2014 Knox Co, 30 Jan 2022 Madison Co, 31 Jan-5 Feb 2024 Buffalo Creek WMA, Scotts Bluff Co, 12 Feb 2021 Kimball Co, 14 Feb 1993 Antelope Co, 17 Feb-15 Mar 2024 Gering Cemetery, Scotts Bluff Co, 18 Feb-3 Apr 2023 Scotts Bluff Co, and 3 Mar 2019 Rock Co.

One was in Dakota Co 6-17 Feb 2023.

A note regarding Pipilo towhees on the Seward-Branched Oak CBC is of interest, suggesting no overlap of Nebraska winter ranges: “I checked and we have had eastern towhees on the count only three times since 1993. In contrast, we have had spotted towhees 13 times (plus one count week bird). We have never had both species on the same count” (Joseph Gubanyi, personal communication). In winter 2023-2024 the DeSoto NWR CBC had a count high seven Spotted as well as two Eastern Towhees.

Comments In the absence of genetic studies, it is unknown what proportion, if any, of “spotted-backed” towhees reported to eBird as Spotted Towhees might be introgressants, a point noted by Scharf (2005), who focused on phenotypic Eastern Towhees in his study because birds with any degree of white spotting on their upperparts were likely to be of indeterminate genotype. If Spotted and Eastern Towhees are “good” species, genetically distinct, interbreeding would be expected to be minimal, and mitigated against by assortative mating in areas of overlap. Sibley and West (1959) suggested that one factor leading to assortative mating might be correlation of degree of back spotting pattern with climatic differences, in particular the amount of shade in towhee habitat (more in eastern forests than in western open brush). In this context, Walsh et al (2020), in a study of hybridization between Bullock’s and Baltimore Orioles in Nebraska, found that hybrid zone width estimates differed between genomic and plumage data, the latter more narrow, and suggested that one explanation might be that selection pressure could be stronger on phenotypic traits. Anecdotal information supporting this theory was provided by T. J. Walker (personal communication), who observed that in his southeastern Lincoln County, Nebraska survey area “I have noted for years that the [Spotted Towhee] songs vary quite a bit – in areas with more deciduous woodland and cedar coverage most of the songs, while still typical of Spotted, have a little hint of “Eastern” to them. In the areas of the canyons with very little woodland, where the landscape is mostly grassland with shrub thickets the songs are quite “dry” and clearly Spotted.” Similarly, in 2020 two southeasterly summer reports of Spotted Towhees were from a prairie and a golf course, both in Saunders Co. These considerations raise the possibility that towhees of apparent intermediate plumages and songs are not necessarily (genetic) introgressants, but might include individuals of sub-populations distributed regionally that have adapted over time to local environmental conditions. If this is true, and introgressants occur in relatively low numbers, the distribution across Nebraska of the degree of back and wing spotting and wing patch extent would be expected to be clinal in both species, reflecting local environmental conditions while maintaining genetic integrity of Spotted and Eastern Towhees. Since songs are learned in these species, mixed songs are to be expected in areas of overlap. Although Sibley and West (1959) pointed out that contact between Spotted and Eastern Towhees in Nebraska was not on a broad front but limited to riparian corridors and surmised that this resulted in “greatly restricted” gene flow, the latter is likely to be largely a consequence of assortative mating, as suggested by these same authors.

In recent years there have been several documented reports in Nebraska of towhees resembling phenotypic Spotted or Eastern Towhees far from their respective expected summer ranges.

In Scotts Bluff County there were six reports of up to six birds at four locations of phenotypic Eastern Towhees in summers 2013-2017, including males singing Eastern songs, and a male “unspotted, singing an Eastern song” (Kathy DeLara, eBird.org). In extensive surveys in the 2000s in Lincoln County, T.J. Walker found 22 Eastern Towhees among the 2307 towhees detected. Data (Silcock, cited above) show that in both counties, however, Spotted Towhees account for 98-99% of towhees. In Keith County, Eastern Towhee is a “rare summer resident”, although only two records are cited; one was seen in 2004 that looked like an Eastern Towhee but sang a Spotted Towhee song (Brown et al 2012). Scharf (2005), during a four-season netting study in the “nesting season”, found 20 Eastern Towhees of phenotype category “0” (“pure” Easterns, see Sibley and West 1959) along the Platte River in Dawson Co 2001-2004.

In the east, phenotypic male Spotted Towhees singing Spotted songs were carefully studied at Rose Creek WMA, Jefferson Co 27 Jul 2016, and another was near Steele City, Jefferson Co the same day. A male at Schramm SP, Sarpy Co 21-29 May 2005 that looked and sang like a Spotted Towhee possessed about half of the white primary patch typical of Eastern Towhee. Spotted Towhees were reported 18 Jun 2020 Saunders Co, and 26 Jul 2013 Seward Co.

Perhaps of interest in this context, Zink (1994, Table 3) found that in three plumage groups of Fox Sparrow, iliaca, unalaschcensis, and schistacea, nine of 139 samples had mtDNA that did not match the plumage type. Similarly, Wright (2019a) noted that “classic … Cassiar-like males [of Dark-eyed Junco] have been photographed as far east as Nova Scotia and New Jersey… but there can be no certainty that the birds are not hybrids….”.

It is clear from this discussion that more study of the distributions of Eastern and Spotted Towhees in the breeding season in Nebraska is needed. It has been assumed that introgression occurs statewide, but the relative contributions of genetics and adaptation (controlled presumably by assortative mating) to the distributions of phenotypic Eastern and Spotted Towhees and putative introgressants is unknown. There have been no genetic studies of this area of species overlap in Nebraska.

Abbreviations

BBS: Breeding Bird Survey
CBC: Christmas Bird Count
NC: Nature Center
NNF: Nebraska National Forest
SHP: State Historical Park
SP: State Park
SRA: State Recreation Area
UNSM: University of Nebraska State Museum
WMA: Wildlife Management Area (State)

Acknowledgement

Photograph (top) of a Spotted Towhee at Fontenelle Forest, Sarpy Co 30 Oct 2008 by Phil Swanson.

Literature Cited

American Ornithologists’ Union [AOU]. 1957. The AOU Check-list of North American birds, 5th ed. Port City Press, Baltimore, Maryland, USA.

Ball, R.M. Jr., and J.C. Avise. 1992. Mitochondrial DNA phylogeographic differentiation among avian populations and the evolutionary significance of subspecies. Auk 109: 626-636.

Banks, R.C., J.W. Fitzpatrick, T.R. Howell, N.K. Johnson, B.L. Monroe Jr., H. Ouellet, J.V. Remsen Jr., and R.W. Storer. 1995. Fortieth supplement to the American Ornithologists’ Union Check-list of North American Birds. Auk 112: 819-830.

Bartos Smith, S. and J.S. Greenlaw. 2020. Spotted Towhee (Pipilo maculatus), version 1.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.spotow.01.

Brown, M.B., S.J. Dinsmore, and C.R. Brown. 2012. Birds of Southwestern Nebraska. Institue of Agriculture and Natural Resources, University of Nebraska, Lincoln.

Gill, F., D. Donsker, and P. Rasmussen (Eds). 2022. IOC World Bird List (v 12.2). Doi 10.14344/IOC.ML.12.2.  http://www.worldbirdnames.org/.

Greenlaw, J.S. 2020. Eastern Towhee (Pipilo erythrophthalmus), version 1.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.eastow.01.

Johnston, R.F. 1965. A directory to the birds of Kansas. Miscellaneous Publication No. 41. University of Kansas Museum of Natural History, Lawrence, Kansas, USA.

Mollhoff, W.J. 2022. Nest records of Nebraska birds. Nebraska Ornithologists’ Union Occasional Paper Number 9.

Pyle, P. 1997. Identification Guide to North American Birds. Part I, Columbidae to Ploceidae. Slate Creek Press, Bolinas, California, USA.

Robbins, M.B. 2018. The Status and Distribution of Birds in Missouri. University of Kansas Biodiversity Institute, Lawrence, Kansas, USA.

Sauer, J.R., D.K. Niven, J.E. Hines, D.J. Ziolkowski, Jr, K.L. Pardieck, J.E. Fallon, and W.A. Link. 2017. The North American Breeding Bird Survey, Results and Analysis 1966 – 2015 (Nebraska). Version 2.07. USGS Patuxent Wildlife Research Center, Laurel, Maryland, USA.

Sauer, J.R., W.A. Link and J.E. Hines. 2020. The North American Breeding Bird Survey – Analysis Results 1966-2019. U.S. Geological Survey data release, https://doi.org/10.5066/P96A7675, accessed 27 Jul 2023.

Scharf, W.C. 2005. New westward breeding records for Eastern Towhees in Central Nebraska. NBR 73: 26-28.

Short, L.L., Jr. 1961. Notes on bird distribution in the central Plains. NBR 29: 2-22.

Sibley, C.G., and D.A. West. 1959. Hybridization in the Rufous-sided Towhees of the Great Plains. Auk 76: 326-328.

Swenk, M.H. 1918. Revisory notes on the birds of Nebraska. Wilson Bulletin 30: 112-117.

Tout, W. 1947. Lincoln County birds. Published by the author, North Platte, Nebraska, USA.

Walsh, J., S.M. Billerman, V.G. Rohwer, B.G. Butcher, and I.J. Lovette. 2020. Genomic and plumage variation across the controversial Baltimore and Bullock’s oriole hybrid zone. Auk 137: 1–15. DOI: 10.1093/auk/ukaa044.

Williams, F. 1976. Southern Great Plains Region. American Birds 30: 90-95.

Wright, R. 2019a. Sparrows of North America. Peterson Reference Guides, Houghton, Mifflin, Harcourt. Boston and New York.

Wright, R. 2019b. A White-eyed Spotted Towhee Observed in Northwestern Nebraska. Western Birds 50:42-43. DOI:10.21199/WB50.1.5.

Zink, R.M. 1994. The Geography of Mitochondrial DNA Variation, Population Structure, Hybridization, and Species Limits in the Fox Sparrow (Passerella iliaca). Evolution 48: 96-111.

Recommended Citation

Silcock, W.R., and J.G. Jorgensen. 2024. Spotted Towhee (Pipilo maculatus). In Birds of Nebraska — Online. www.BirdsofNebraska.org

Birds of Nebraska – Online

Updated 23 Aug 2024