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Photo by Judd Patterson
Photo Copyright Judd Patterson
Spotted Towhee
Pipilo maculatus
NatureServe conservation status
Global (G-rank): G5
State (S-rank): S4S5B,S4N
External links
General information
The spotted towhee, Pipilo maculatus, is a long-tailed sparrow that breeds in thickets, brush, and other areas of dense shrubby growth in temperate and subtropical western North America, the highlands of Mexico, and in parts of Guatemala. It winters in the American West, the Midwest, and in parts of Mexico and Guatemala. In Utah, the spotted towhee is common throughout the state on the lower slopes of mountains. It is especially common along the Wasatch Front, where individuals remain year-round. Breeding occurs along stream sides, primarily in the northern valleys of the state.
The diet of the spotted towhee varies by season. During the breeding season, it prefers animal matter (eg. insects, spiders, millipedes), but during other periods of the year, it consumes mostly plant material (eg. acorns, seeds, fruits). It forages for food along the ground in areas with adequate cover. Individuals scratch the ground to displace leaves and loose soil, or less commonly, they will forage above ground, plucking insects and fruits off of trees. Pairs form on breeding grounds, and then a nest is built either on, or just above, the ground. The female incubates her clutch of three to five eggs for about two weeks. The young are born blind and nearly naked, and both parents feed the young. Hatchlings leave the nest after ten days, but they are unable to fly for about another week. The parents continue to feed the young for about a month after they young have left the nest.
Species range
BREEDING: southern British Columbia, southern Alberta, and southern Saskatchewan south to southern California, northwestern Baja California, southern Nevada, Arizona, and through the Mexican highlands to Chiapas and central Guatemala, and east to the central Dakotas, north-central and western Nebraska, central Colorado, eastern New Mexico, and extreme western Texas; disjunctly in southern Baja California (AOU 1983, Greenlaw 1996). See Sauer et al. (2000) for large-scale mapped density estimates (range-wide) based on North American Breeding Bird Survey (BBS) data. NON-BREEDING: south coastal British Columbia, Nevada, Utah, and Colorado (casually farther north) south to Baja California, northern Sonora, through the Mexican breeding range to central Guatemala, and to south-central Texas (AOU 1983).
Migration
Migration patterns variable among different populations. Northern interior breeding populations are migratory or partly migratory; increasingly sedentary southward and near coastal areas. Migratory populations arrive in northern breeding areas in March-April (Terres 1980, Greenlaw 1996). Pacific Coastal birds mostly resident, although some in interior coast are short-distance migrants. In some areas summer residents migrate and are replaced by more northern birds that overwinter (Greenlaw 1996). Spring arrival in northern parts of range between late March and mid-May; fall departure between early September and early October (Greenlaw 1996). Northern Great Plains populations winter in southwest New Mexico to southeast Texas and Mexico. South-central Rocky Mountain populations winter from Arizona to east-central Texas and Mexico. North Central Rocky Mountain birds winter from southern California to southeast Arizona (Greenlaw 1996).
Habitat
BREEDING: Uses a wide variety of shrubby habitats characterized by deep litter and humus on ground, and sheltering vegetation overhead (Greenlaw 1996). Undergrowth of open woodland, forest edge, second growth, brushy areas, chaparral, riparian thickets, woodland (AOU 1998). In northern Great Plains, found in shrubby riparian thickets along streams, rivers and coulees, also in woodland undergrowth. In interior mountains and plateaus, uses riparian thickets, open south-facing slopes of ridges, and canyon bottoms. In southern Rocky Mountains, common in pine-oak and pinyon-juniper forests, uncommon in mixed coniferous forests, and rare in ponderosa pine and aspen forests (Hejl et al. 1995). In Colorado pinyon-juniper woodlands, associated with moderately open areas on steep slopes with high shrub cover (Sedgwick 1987). In Pacific Northwest sometimes occurs in shrubby forest successional stages. In California Coast Range, found in chaparral and rose-blackberry thickets (ROSA-RUBRUS; Greenlaw 1996). In Mexico, uses typical brushy woodland and scrub, understory of pine forests and pine-oak woodlands, chaparral, semi-open areas with scattered bushes and brush (Howell and Webb 1995). Associated with an extensive list of shrubby and thicket-forming plants, including: scrub oaks (QUERCUS spp.), Pinyon Pine (PINUS EDULIS), juniper (JUNIPERUS), yucca (YUCCA spp.), baccharis (BACCHARIS spp.), willow (SALIX spp.), senecio (SENECIO spp.), madrone (ARBUTUS spp.), rose (ROSA spp.), blackberry (RUBUS spp.), saltbush (ATRIPLEX spp.), mountain mahogany (CERCOCARPUS sp.), toyon (HETEROMELES ARBUTIFOLIA), elder (SAMBUCUS spp.), buckthorn (RHAMNUS spp.), sagebrush (ARTEMISIA spp.), snowberry (SYMPHORICARPOS spp.), chamise (ADENOSTOMA spp.), manzanita (ARCTOSTAPHYLOS spp.), sumac (RHUS spp.), Pacific poison-oak (RHUS DIVERSILOBA), ceanothus (CEANOTHUS spp.), and grape (VITIS sp.; Greenlaw 1996). In Mexico, also found in bushy composites (Greenlaw 1996). Constructs a well-built cup nest in litter on ground, under bush or brush pile, clump of grass, or elevated in vines, trees, bushes, usually between 0.6 and 3.6 m from the ground. Often in relatively exposed conditions, though concealed by nearby plants (Greenlaw 1996; Baicich and Harrison 1997). Elevation of nests may be influenced by rainfall or predation (Greenlaw 1996). NONBREEDING: Uses similar shrubby habitats and thickets in wintering areas. Nonbreeding birds may occur in areas where towhees do not breed (Greenlaw 1996). In Arizona, winters in Upper Sonoran foothills, in brushy canyons and river valleys of southeastern Arizona, and uncommonly in riparian woodland, willows and marshes along the lower Colorado River (Phillips et al. 1964, Rosenberg et al. 1991).
Food habits
Forages on the ground beneath shrubs and undergrowth, using a two-footed scratching maneuver to find food among loose debris (Greenlaw 1996). Eats various invertebrates, seeds, small fruits, some small vertebrates (Terres 1980). Diet includes many types of beetles (Coleoptera); grasshoppers and crickets (Orthoptera); true bugs (Heteroptera); ants and wasps (Hymenoptera); flies (Diptera); butterflies and moths, including larvae (Lepidoptera); leafhoppers, aphids and allies (Homoptera); spiders (Araneae); millipedes (Diplopoda); and sowbugs (Isopoda; Greenlaw 1996). Commonly eats seeds and fruits, particularly in nonbreeding season, and sometimes blossoms and young leaves (Dahlsten et al. 1985, Greenlaw 1996). In California, stomach contents (N = 6) were 84.1% animal, 13.2% vegetable and 2.7% mineral (Dahlsten et al. 1985), but relative composition varies with season and locality (Greenlaw 1996). See Greenlaw (1996) for extensive list of plants found in diet. Less known about composition of diet in nonbreeding season, particularly types of invertebrate prey.
Ecology
In nonbreeding season, forms loose flocks and can be somewhat gregarious. Family groups remain together throughout summer (Ehrlich et al. 1988). See Greenlaw (1996) for density estimates and patterns.
Reproductive characteristics
Clutch size usually 3-5 (range 2-6). Will renest if first broods suffer mortality, and second broods are uncommon. Incubation, entirely by female, lasts 12-14 days. Only female broods but both parents feed young and remove fecal sacs. Young leave nest unable to fly at 9-11 days; parents continue to feed dependent young out of nest for another 30 days (Ehrlich et al. 1988, Greenlaw 1996, Baicich and Harrison 1997). A host to brood parasites (see Threats above).
Threats or limiting factors
Vulnerable to land management activities that reduce or remove brushy vegetation, particularly along streamsides, in forest understories, and in dry shrubland habitats. PARASITISM: A frequent host to cowbird brood parasitism; host to Brown-headed Cowbird (MOLOTHRUS ATER) in North America and Bronzed Cowbird (M. AENEUS) in Guatemala. Apparently does not cover or reject cowbird eggs (Ehrlich et al. 1988, Greenlaw 1996). Incidence of parasitism has apparently increased as Brown-headed Cowbird has expanded range and increased in abundance (Greenlaw 1996). Also an occasional host to brood parasitism and egg-dumping by California Quail (CALLIPEPLA CALIFORNICA), but no information is available on rate of occurrence (Greenlaw 1996). PREDATION: Predators include Cooper's (A. COOPERI) and Sharp-shinned Hawks (A. STRIATUS; Reynolds and Meslow 1984, Kennedy and Johnson 1986). Other suspected predators of nests and young include King Snake (LAMPROPELTIS GETULUS), Western Scrub-Jay (APHELOCOMA CALIFORNICA), Striped Skunk (MEPHITIS MEPHITIS), Long-tailed Weasel (MUSTELA FRENATA), California Ground Squirrel (SPERMOPHILUS BEECHEYI), and Western Gray Squirrel (SCIURUS GRISEUS, Greenlaw 1996).
References
- Behle, W. H., Sorensen, E. D. and C. M. White. 1985. Utah birds: a revised checklist. Utah Museum of Natural History, Occasional Publication No. 4. Salt Lake City, UT.
- Greenlaw, J. S. 1996. Spotted Towhee (Pipilo maculatus). Birds of North America 263.
