Spiza americana - (Gmelin, 1789)
Dickcissel
Other English Common Names: dickcissel
Other Common Names: Papa-Capim-Americano
Taxonomic Status: Accepted
Related ITIS Name(s): Spiza americana (Gmelin, 1789) (TSN 179165)
French Common Names: dickcissel d'Amérique
Spanish Common Names: Arrocero Americano
Unique Identifier: ELEMENT_GLOBAL.2.106001
Element Code: ABPBX65010
Informal Taxonomy: Animals, Vertebrates - Birds - Perching Birds
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Aves Passeriformes Cardinalidae Spiza
Genus Size: A - Monotypic genus
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Concept Reference
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Concept Reference: American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Concept Reference Code: B98AOU01NAUS
Name Used in Concept Reference: Spiza americana
Taxonomic Comments: See Tamplin et al. (1993) for information on relationships of this species and among the Cardinalidae.
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 09Apr2016
Global Status Last Changed: 04Dec1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: Widespread and common. Population decline appears to have leveled off.
Nation: United States
National Status: N5B (19Mar1997)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alabama (S2N,S4B), Arizona (S2M), Arkansas (S5B), Colorado (S3B), Connecticut (S1B), District of Columbia (SHB), Florida (SNA), Georgia (S3S4), Illinois (S4), Indiana (S4B), Iowa (S4B,S4N), Kansas (S5B), Kentucky (S4S5B), Louisiana (S4B), Maryland (S3B), Massachusetts (SXB,S1N), Michigan (S3), Minnesota (SNRB), Mississippi (S4B), Missouri (SNRB), Montana (S4B), Nebraska (S5), New Jersey (S4B,S4N), New Mexico (S1B,S4N), North Carolina (S2B), North Dakota (SNRB), Ohio (S3), Oklahoma (S4B), Pennsylvania (S2B), South Carolina (SNRB), South Dakota (S4B), Tennessee (S4), Texas (S4B), Virginia (S2S3B), West Virginia (S1B), Wisconsin (S3B), Wyoming (S1)

Other Statuses

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: >2,500,000 square km (greater than 1,000,000 square miles)
Range Extent Comments: BREEDING: eastern Montana and southern Saskatchewan east across Great Lakes region to southern Ontario and central New York, south to northeastern Wyoming, eastern Colorado, southern Texas, central Alabama, and South Carolina; formerly in Atlantic lowlands from Massachusetts to North Carolina (AOU 1998). NON-BREEDING: from Nayarit south through Central America to South America; mostly from Panama to Guianas and northern Brazil; Colombia and Venezuela and in much smaller numbers in Guianas and extreme northern Brazil, sometimes Trinidad (Ridgely and Tudor 1989), locally in Atlantic and Gulf lowlands of U.S. (AOU 1998). Predominant wintering area is the llanos of Venezuela in the states of Portuguesa, Cojedes, and Guarico (Basili and Temple 1999).

Number of Occurrences: 6 - 20
Number of Occurrences Comments: Number of breeding season occurrences not determined but has a widespread range. Non-breeding season populations concentrated into relatively few roosts in Venezuela, with up to 2,950,000 birds counted in a single roost and 40% of 16 roosts containing over 1 million individuals. Individual roosts may contain up to 30% of the entire global population (Basili and Temple 1999).

Population Size: 10,000 to >1,000,000 individuals
Population Size Comments: BREEDING: In southeast Nebraska, 1989-1990, dickcissel and grasshopper sparrow (AMMODRAMUS SAVANNARUM) were most abundant species encountered in grassland (King and Savidge 1995). Relative abundance reported from survey-wide North American Breeding Bird Survey (BBS), 1966-1996, was 16.29 birds per survey. Highest relative abundance reported in Kansas (63.49 birds per survey). Next highest relative abundances in Missouri and Oklahoma (43.27 and 42.28 birds per survey route respectively; Sauer et al. 1997). Some individuals winter in North America. Christmas Bird Count (CBC) 1959-1988 survey-wide relative abundance was 0.04 birds per 100 survey hours. Highest relative abundance on CBC reported in Massachusetts (0.05 birds per 100 survey hours) for same period (Sauer et al. 1996). NON-BREEDING: Total population estimated at over 6 million, based on roost counts in Venezuela in January and February, 1993 (Basili and Temple 1999).

Overall Threat Impact Comments: Primary cause of mortality apparently poisoning of roosting birds in Venezuela by aerial or ground application of parathion and other pesticides during non-breeding season (Basili and Temple 1999). Local breeding populations are threatened by loss of nests and nestlings when fields are mowed. NON-BREEDING SEASON: Night roosts have been sprayed with organophosphates to kill dickcissels which are considered a pest species especially by rice and sorghum farmers (Basili and Temple 1995). Some roosts may contain up to 3 million birds and, if targeted, could significantly reduce numbers. HABITAT: Local populations are threatened by loss of nests and nestlings when fields are mowed. Not considered area sensitive, however (Herkert 1994, Swanson 1996). PARASITISM: Brood parasitism by the Brown-headed Cowbird (MOLOTHRUS ATER) occurs at variable rates (Taber 1947, Hergenrader 1962, Overmire 1962, Friedmann et al. 1977, Fleischer 1986, Klute 1994) but, if present, can lower productivity (Overmire 1963; Wiens 1963; Zimmerman 1982, 1983; Schartz 1969; Elliott 1976; Fretwell 1977; Winter 1998). When comparing brood parasitism rates in the central Great Plains, Basili (1997) found significantly higher brood parasitism rates in Kansas and Nebraska and significantly lower rates in Texas. Rates of brood parasitism varied from 2.8% of 143 nests in Texas (Steigman 1993) to 94.7% of 19 nests in northeastern Kansas (Elliott 1976). This variation in the rate of brood parasitism was related to the variation in cowbird density in different areas of the central Great Plains (Basili 1997). Brood parasitism by cowbirds can be nest density dependent; areas with low nesting densities of Dickcissels, such as tallgrass prairies, can experience higher intensities and frequencies of parasitism than areas with high nesting densities, such as oldfields (Fretwell 1977; Zimmerman 1982, 1983). However, Fleischer (1986) found that rates of brood parasitism in Kansas were not related to Dickcissel nest density, but were related to nest height. Parasitized nests were placed significantly higher (mean of 0.65 meters) above the ground than unparasitized nests (mean of 0.34 meters). Fretwell (1972) observed that higher rates of brood parasitism occurred when nests were placed near Red-winged Blackbird (AGELAIUS PHOENICEUS) nests. In Illinois, nests located within 50 meters of woody edges or other tall (more than 2 meters), woody vegetation were more than twice as likely to be parasitized as nests more than 50 meters from woody vegetation (J.R. Herkert and S.K. Robinson, unpubl. data). In southwestern Missouri, the frequency of parasitism increased significantly with proximity to shrubby edges; frequency of brood parasitism was highest less than 50 meters from a shrubby edge (Winter 1998). However, in Kansas, significantly higher brood parasitism rates were not found for nests less than 100 meters from wooded edges (Jensen, pers. comm.). In Missouri tallgrass prairie fragments, the rate of brood parasitism was not related to fragment size (Winter 1998). PREDATION: Known predators in winter in Venezuela include: Merlin (FALCO COLUMBARIUS), Aplomado Falcon (F. FEMORALIS), Peregrine Falcon (F. PEREGRINUS), Bat Falcon (F. RUFIGULARIS), American Kestrel (F. SPARVERIUS), Pearl Kite (GAMPSONYX SWANSONII), White-tailed Kite (ELANUS CAERULEUS), Roadside Hawk (BUTEO MAGNIROSTRIS), Short-tailed Hawk (B. BRACHYURUS), Gray Hawk (ASTURINA NITIDA), Harris's Hawk (PARABUTEO UNICINCTUS), Long-winged Harrier (CIRCUS BUFFONI), Barn Owl (TYTO ALBA), Short-eared Owl (ASIO FLAMMEUS), jaguarundi (FELIS YAGOUAROUNDI), huron (GALICTIS VITTATA), and tayra (EIRA BARBARA) (Basili and Temple 1999). PESTICIDES: In wheat fields treated with a mixture of toxaphene and methyl parathion in southeastern Missouri, Dickcissels showed high levels of cholinesterase inhibition activity in their brains. However, no dead or abnormally behaving birds were observed (Niethammer and Baskett 1983). HUNTING: Commonly hunted across winter range for food and pest control. Methods include slingshots, throwing sticks, clubbing, and shooting (Basili and Temple 1999).

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: Initial population decline recorded after North American Breeding Bird Survey (BBS) began in 1966 but decline appears to have leveled off. BBS data indicate a significant population decline in eastern (-4.2 percent annual change; P = 0.00; n = 283) and central (-1.0 percent annual change; P = 0.00; n = 499) North America, 1966-1996 (Sauer et al. 1997). Significant declines, 1966-1996, reported in Illinois, Iowa, Kentucky, Missouri, North Dakota, and Wisconsin. Only increase recorded in Oklahoma (1.5 percent annual change; P = 0.02; n = 58) for the same period. Trend increased after 1980. Significant population increase in central region (0.8 percent annual change; P = 0.02; n = 465) of North America, 1980-1996 (Sauer et al. 1996). For twelve states, significant decreases for period 1966-1979; for 1980-1996, however, significant increases in two of these states, non-significant increases in nine states. Only continuing significant decrease in Missouri for the same period (Sauer et al. 1997). Although most birds winter in the tropics, some stay in coastal and southern United States through winter. Christmas Bird Count shows non-significant (P larger than 0.10) surveywide decline 1959-1988 (-0.4 percent annual decline; n = 255; Sauer et al. 1996). Termination of the USDA Conservation Reserve Program and a return of enrolled land to cultivation are expected to cause a population decline of 17% in North Dakota (Johnson and Igl 1995).

Other NatureServe Conservation Status Information

Protection Needs: Protect areas (more than 10 hectares for Illinois grassland) of suitable habitat (Herkert 1991a,b). In Missouri, abundance (Swengel 1996) and productivity (Winter 1996, 1998) increased with increasing prairie size.

Distribution
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Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: eastern Montana and southern Saskatchewan east across Great Lakes region to southern Ontario and central New York, south to northeastern Wyoming, eastern Colorado, southern Texas, central Alabama, and South Carolina; formerly in Atlantic lowlands from Massachusetts to North Carolina (AOU 1998). NON-BREEDING: from Nayarit south through Central America to South America; mostly from Panama to Guianas and northern Brazil; Colombia and Venezuela and in much smaller numbers in Guianas and extreme northern Brazil, sometimes Trinidad (Ridgely and Tudor 1989), locally in Atlantic and Gulf lowlands of U.S. (AOU 1998). Predominant wintering area is the llanos of Venezuela in the states of Portuguesa, Cojedes, and Guarico (Basili and Temple 1999).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
NOTE: The maps for birds represent the breeding status by state and province. In some jurisdictions, the subnational statuses for common species have not been assessed and the status is shown as not-assessed (SNR). In some jurisdictions, the subnational status refers to the status as a non-breeder; these errors will be corrected in future versions of these maps. A species is not shown in a jurisdiction if it is not known to breed in the jurisdiction or if it occurs only accidentally or casually in the jurisdiction. Thus, the species may occur in a jurisdiction as a seasonal non-breeding resident or as a migratory transient but this will not be indicated on these maps. See other maps on this web site that depict the Western Hemisphere ranges of these species at all seasons of the year.
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AL, AR, AZ, CO, CT, DC, FL, GA, IA, IL, IN, KS, KY, LA, MAextirpated, MD, MI, MN, MO, MS, MT, NC, ND, NE, NJ, NM, OH, OK, PA, SC, SD, TN, TX, VA, WI, WV, WY

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: NatureServe, 2002


U.S. Distribution by County Help
State County Name (FIPS Code)
CT Hartford (09003), New Haven (09009)
MD Frederick (24021)*, Howard (24027)*, Montgomery (24031)*
MI Alger (26003), Allegan (26005), Alpena (26007), Barry (26015), Berrien (26021), Branch (26023), Calhoun (26025), Eaton (26045), Huron (26063), Ingham (26065), Ionia (26067), Isabella (26073), Jackson (26075), Kalamazoo (26077), Lapeer (26087), Lenawee (26091), Livingston (26093), Mecosta (26107), Monroe (26115), Montcalm (26117), Muskegon (26121), Osceola (26133), Sanilac (26151), St. Joseph (26149), Tuscola (26157), Van Buren (26159), Washtenaw (26161), Wayne (26163)
NM Dona Ana (35013), Quay (35037)
PA Beaver (42007), Chester (42029), Clarion (42031), Clearfield (42033)*, Cumberland (42041), Erie (42049)*, Franklin (42055), Jefferson (42065)*, Lawrence (42073), Mercer (42085)*, Somerset (42111), Westmoreland (42129)
WY Campbell (56005)*, Crook (56011)*, Fremont (56013)*, Goshen (56015)*, Johnson (56019)*, Laramie (56021)*, Sheridan (56033), Sweetwater (56037), Weston (56045)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Farmington (01080207)+, Quinnipiac (01100004)+
02 Brandywine-Christina (02040205)+, Lower Susquehanna-Swatara (02050305)+, Patuxent (02060006)+*, Conococheague-Opequon (02070004)+, Middle Potomac-Catoctin (02070008)+*, Monocacy (02070009)+*
04 Tacoosh-Whitefish (04030111)+, Little Calumet-Galien (04040001)+, St. Joseph (04050001)+, Black-Macatawa (04050002)+, Kalamazoo (04050003)+, Upper Grand (04050004)+, Lower Grand (04050006)+, Thornapple (04050007)+, Pere Marquette-White (04060101)+, Muskegon (04060102)+, Thunder Bay (04070006)+, Birch-Willow (04080104)+, Pine (04080202)+, Flint (04080204)+, Cass (04080205)+, St. Clair (04090001)+, Detroit (04090004)+, Huron (04090005)+, Ottawa-Stony (04100001)+, Raisin (04100002)+, Chautauqua-Conneaut (04120101)+*
05 Clarion (05010005)+, Middle Allegheny-Redbank (05010006)+*, Conemaugh (05010007)+, Youghiogheny (05020006)+, Upper Ohio (05030101)+, Shenango (05030102)+*, Connoquenessing (05030105)+
10 Lower Wind (10080005)+*, Upper Tongue (10090101)+, Middle Fork Powder (10090201)+*, Upper Powder (10090202)+*, South Fork Powder (10090203)+*, Middle Powder (10090207)+*, Little Powder (10090208)+*, Upper Little Missouri (10110201)+*, Upper Cheyenne (10120103)+*, Angostura Reservoir (10120106)+*, Beaver (10120107)+*, Upper Belle Fourche (10120201)+*, Lower Belle Fourche (10120202)+*, Redwater (10120203)+*, Middle North Platte-Scotts Bluff (10180009)+*, Horse (10180012)+*, Upper Lodgepole (10190015)+*
11 Upper Canadian-Ute Reservoir (11080006)+
13 Jornada Draw (13030103)+
14 Upper Green-Slate (14040103)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A small bird.
Reproduction Comments: Clutch size is 3-5 (usually 4). Typically produces two broods per year. Incubation lasts 11-13 days, by female. Young are tended by female, leave nest at 7-10 days, unable to fly until 11-12 days.
Ecology Comments: Mean territory size on breeding ground in tallgrass prairie in Kansas ranged from 0.45 to 0.57 hectares, whereas the mean territory size in oldfields ranged from 0.15 to 0.95 hectares (Zimmerman 1966; Schartz 1969; Petersen 1978; Finck 1983, 1984). The mean territory size in an Illinois oldfield ranged from 0.38 to 0.54 hectares (Harmeson 1972, 1974). The mean territory sizes in ungrazed and grazed tallgrass prairie in Oklahoma were 0.25 hectares and 0.47 hectares, respectively (Overmire 1963). Larger territory sizes of 1.4 hectares and 1.5 hectares were reported for tallgrass prairie in Iowa and tallgrass pasture in Oklahoma, respectively (Wiens 1971, Laubach 1984). In Kansas, males commonly returned to the same breeding area in successive years (Zimmerman and Finck 1989).

In northern winter, occurs in small groups or concentrated in dense flocks of 100s or 1000s (Hilty and Brown 1986) or up to 3 million in agricultural areas of Venezuelan llanos (Basili and Temple 1999).

Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: Y
Mobility and Migration Comments: Arrives in breeding areas April-May (Terres 1980). Migration in Costa Rica occurs early September-late October and early April to mid-May (Stiles and Skutch 1989). Arrives in Colombia by mid-September, departs by early May (Hilty and Brown 1986); present in South America mostly October-April (Ridgely and Tudor 1989).
Terrestrial Habitat(s): Cropland/hedgerow, Grassland/herbaceous, Old field, Savanna
Habitat Comments: BREEDING: Grassland, meadows, savanna, cultivated lands, brushy fields (AOU 1998). Nests on ground in grass or rank herbage, or raised a little above ground, in grass tufts or tall weeds, or in low shrubs or trees, up to about 2 meters above ground but usually low (Harrison 1978). Prefer habitat with dense, moderate to tall vegetation (particularly with some forbs) and moderately deep litter (Gross 1921, 1968; Harmeson 1972, 1974; Wiens 1973; Harrison 1974; Petersen 1978; Rotenberry and Wiens 1980; Roth 1980; Finck 1983, 1984; Skinner et al. 1984; Kahl et al. 1985; Frawley 1989; Sample 1989; Delisle and Savidge 1997; Winter 1998). Suitable habitats are found in oldfields, hayfields, fencerows, hedgerows, road rights-of-way, planted cover (e.g., Conservation Reserve Program [CRP] fields and dense nesting cover), and moderately grazed and idle prairie (Gross 1921, 1968; Taber 1947; Sauer 1953; Ely 1957; Hergenrader 1962; Graber and Graber 1963; Meanley 1963; Emlen and Wiens 1965; Blankespoor 1970; Berry 1971; Harmeson 1972, 1974; Harrison 1974; Stewart 1975; Sealy 1976; Petersen 1978; Rotenberry and Wiens 1980; Roth 1980; Faanes 1981; Finck 1983, 1984; Renken 1983; Skinner et al. 1984; Kahl et al. 1985; Basore et al. 1986; Sample 1989; Camp and Best 1993; Johnson and Schwartz 1993; Steigman 1993; Faanes and Lingle 1995; Johnson and Igl 1995; King and Savidge 1995; Hull et al. 1996; Best et al. 1997; Delisle and Savidge 1997; Winter 1998; W. E. Jensen, Emporia State University, Emporia, Kansas, pers.comm.). A high abundance of forbs provides perches, nesting cover, nest support, and possibly increased invertebrate abundance (Blankespoor 1970; Zimmerman 1971; Harmeson 1972, 1974; Birkenholz 1973; Skinner et al. 1984; Frawley and Best 1991; Klute 1994; Patterson 1994; Patterson and Best 1996; Winter 1998).

In southwestern Missouri, Skinner et al. (1984) found Dickcissels in medium to tall grasslands with many tall forbs, conditions that were found in moderately grazed to idle cover. Skinner (1974, 1975) reported that densities in northwestern Missouri were highest with moderate amounts of forbs, and were lower when forbs were either very scarce or very abundant. In southwestern Missouri tallgrass prairie fragments, density increased with vegetation height (Winter 1998). In Kansas, densities were higher in oldfields compared with prairie (Petersen 1978; Finck 1983, 1984). Fence posts, small trees, and tall forbs are commonly used as song perches (Laubach 1984, Kahl et al. 1985).

Nests are elevated in grasses, forbs, shrubs, or trees, and less commonly on the ground in thick vegetation (Gross 1921; Overmire 1962, 1963; Meanley 1963; Zimmerman 1966; Blankespoor 1970; Fretwell 1977; Frawley 1989; Winter 1998). Nest heights range from 0 to 2 meters (Taber 1947, Ely 1957, Meanley 1963, Von Steen 1965, Gross 1968, Berry 1971, Roth 1980, Laubach 1984, Winter 1998). In Kansas, the majority of nests were in forbs (Zimmerman 1966, Blankespoor 1970), followed by isolated American elm (ULMUS AMERICANA) saplings, thistle (CIRSIUM SP.), and grass (Blankespoor 1970). In tallgrass pasture in Kansas, most nests were adjacent to patches of dogwood (CORNUS) (Fleischer 1986). In Oklahoma, nested on the ground and in greenbrier (SMILAX BONA-NOX) thickets within oldfields; nest heights in an oldfield ranged from 3 to 60 centimeters (Ely 1957, Berry 1971). Ground nests were more successful than elevated nests in Oklahoma; as the season progressed, however, nests were built higher above the ground (Overmire 1963). In Nebraska, nests averaged 34 centimeters high in alfalfa (MEDICAGO SATIVA) and wild rose (ROSA SP.) (Von Steen 1965). In an Illinois oldfield, nested in live forbs and dead vegetation; most nests were in wild aster (ASTER PILOSUS), but nests in dead vegetation were more productive (Harmeson 1972, 1974). Nests in trees or hedges in Illinois were 0.6-1.8 meters high (Gross 1968). In Missouri, most nests were found in individual forb plants; nests were occasionally placed above the ground in clumps of grass or in shrubs (Sauer 1953, Skinner et al. 1984, Winter 1998). In Iowa placed nests in forbs, grasses, shrubs, and deciduous tree saplings (Best et al. 1981). Nests in Texas were associated with woody plants and were surrounded by dense grass or forbs (Roth 1980). Within tallgrass prairie in Texas, nests were located most often in green milkweed (ASCLEPIAS VIRIDIFLORA), sensitive briar (SCHRANKIA ROEMERIANA), and eastern gammagrass (TRIPSACUM DACTYLOIDES) (Steigman 1993).

Hayland is used more frequently for nesting than cropland (Gross 1968, Faanes and Lingle 1995). In Nebraska, hayland was commonly used for nesting, with fewer nests found in wet prairie, wetland, upland prairie, lowland forest, or cropland (Von Steen 1965, Faanes and Lingle 1995). Ducey and Miller (1980) found unsuccessful nests in alfalfa (nest loss was caused by mowing) and oat fields (unknown cause of nest loss) in Nebraska. In Illinois, hayland was preferred for nesting, whereas no nests were found in pasture or cropland (Gross 1968). In Wisconsin also commonly nested in hayfields (Taber 1947).

Occasionally nest in strip cover such as roadside ditches, fencerows, and grassed waterways (Gross 1921; Meanley 1963; Basore et al. 1986; Bryan and Best 1991, 1994; Camp and Best 1994; Warner 1994). In Illinois, nested in wider tracts of strip cover, such as waterways (7-28 meters wide) as opposed to fencerows (1-3 meters wide) (Warner 1994). Nests were found in grassed waterways in Iowa (Bryan and Best 1991, 1994) and road rights-of-way in Nebraska (Hergenrader 1962) that were planted to smooth BROME (BROMUS INERMIS). In Iowa, preferred nesting in strip cover over tilled or untilled (idle in fall and spring and containing year-round crop residue) cropland (Basore et al. 1986). The probability of occurrence was significantly greater in Iowa grassed waterways that had greater forb cover than those with lesser forb cover (Bryan and Best 1994). In Arkansas, densities were higher in brushy roadside borders than in open fields (Meanley 1963). Nests in road rights-of-way or other edge habitats, however, can experience high rates of depredation (Basore et al. 1986, Camp and Best 1994).

In portions of Colorado, Kansas, Montana, Nebraska, Oklahoma, South Dakota, Texas, Wisconsin, and Wyoming, abundance was related positively to percent grass cover, percent litter cover, vegetation density, vegetation height, and litter depth (Rotenberry and Wiens 1980). In Iowa, abundance was related negatively to tree species richness, density, and size, as well as sapling density and the horizontal patchiness of trees (Best et al. 1981). In Nebraska, abundance was related positively to litter depth, vertical density, and percent forb cover (Delisle and Savidge 1997). In a Michigan alfalfa field, occupied areas of low plant diversity; low vegetation density at a height of 5 centimeters; and high litter cover, vegetation height, and vertical density of vegetation (Harrison 1974).

NON-BREEDING: A variety of open habitats, second growth, and scrub (AOU 1998). Often in rice-growing regions in winter (Ehrlich et al. 1992). Prefers to roost in sugarcane (SACCHARUM spp.) fields, but if not available, will utilize bamboo, cattail marshes, grasses, and shrubs (Basili and Temple 1999).

Adult Food Habits: Granivore, Invertivore
Immature Food Habits: Granivore, Invertivore
Food Comments: Eats weed seeds, grain, insects, and spiders; mainly grain and seeds in winter; forages on ground (Terres 1980) or picks seeds off seedheads (Stiles and Skutch 1989). Young nestlings are fed insects. Predominant items in diet during non-breeding season in Venezuela were rice, sorghum, and three species of wild grasses (ROTTOBOELLIA COCHINCHINENSIS, ORIZYA LATIFOLIA, ISCHAEMUM RUGOSUM) (Basili and Temple 1999).
Adult Phenology: Diurnal
Immature Phenology: Diurnal
Length: 16 centimeters
Weight: 29 grams
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Main threat appears to be heavy mortality during non-breeding season, when birds are very concentrated in relatively few nocturnal roosts, leaving them vulnerable to lethal control methods practiced by farmers (Basili and Temple 1999). In breeding season, primary goal is to minimize disturbance to suitable habitat (Herkert 1994a).

Adjust timing and type of management according to habitat. For example, xeric and mesic prairies may differ in rates of postburn litter accumulation, such that xeric prairies should be burned less frequently (Swengel 1996).

To increase abundance and productivity, avoid conducting grazing and burning or grazing and haying treatments on the same site (Eddleman 1974, Swengel 1996, Zimmerman 1997). Simultaneous burning and grazing may simulate drought conditions, reducing above-ground herbaceous vegetation and decreasing nest-site availability (Zimmerman 1997).

On privately owned rangelands, work to create a mosaic of sites that are suitable for Dickcissel productivity as well as sites that will benefit cattle production (Zimmerman 1997). Burned and grazed sites benefit cattle production, whereas sites that are idle, only burned, or only moderately grazed provide dense herbaceous vegetation preferred by Dickcissels.

To enhance the use of grassy edges, establish grassy filter strips along fields and existing edges and locate hay or small grains near wide grassland corridors (Warner 1994). Create large, grassy areas near small prairie fragments; small prairie fragments can support higher densities if surrounded by other grassland habitat (Winter 1998).

Burn or mow grasslands and roadsides in blocks on a 3-5 year rotational basis to maintain vegetation quality (Westemeier and Buhnerkempe 1983, Camp and Best 1993). Burn no more than 20-30 percent of a prairie fragment annually in a rotational manner (Winter 1998). Burning is preferred to haying, because vegetation recovers more quickly after burning than haying (Winter 1998).

Delay mowing until after the peak nesting period (i.e., until after mid-August), when possible, to improve productivity (Gross 1921, 1968; Harrison 1974; Harrison and Brewer 1979; Bryan and Best 1991; Herkert 1994a; Zimmerman 1997). However, do not mow later than mid-September in northern regions, because vegetation will not have time to recover before the winter or the following spring (Bryan and Best 1991). Avoid mowing or eliminating forbs, brush, and hedgerows (Overmire 1963).

To maintain plant vigor in tallgrass prairie, do not graze warm-season grasses to less than 25 centimeters during the growing season (Skinner 1975).

Klute (1994) suggested allowing Conservation Reserve Program (CRP) grasslands to be grazed in Kansas to encourage forb growth.

Provide areas of tall, dense planted cover, such as that provided in CRP fields or dense nesting cover (Renken and Dinsmore 1987). Allow retired agricultural fields to undergo secondary succession (Klute 1994). However, when succession begins to advance to the point of becoming unsuitable for breeding, implement burning and/or grazing to control the growth of woody vegetation (Eddleman 1974).

Species Impacts: Considered a major agricultural pest on rice and sorghum in Venezuela. Methods of control in Venezuela include firecrackers and organophosphate pesticides such as Parathion and Azodrin. Application methods include poisoning watering holes, spraying feeding areas, and spraying nocturnal roosts from air or ground (Basili and Temple, pers. comm.).
Preserve Selection & Design Considerations: Although information is inconclusive, appear to be relatively tolerant of habitat fragmentation on a distributional level (Herkert 1991a,b; Herkert et al. 1993; Winter 1998). In Illinois, abundance in burned tallgrass prairie fragments was related inversely to area (Herkert 1994a). Conversely, in idle tallgrass prairie fragments in Illinois, no relationship between abundance and fragment size was found (Herkert 1991a, 1994b); the minimum area needed was found was less than 10 hectares (Herkert 1991a,b). In Nebraska, the minimum area was 9 hectares (Helzer 1996). Abundance in Missouri was related positively with prairie size (Swengel 1996). Winter (1996, 1998) found that the distribution and density in Missouri did not indicate area sensitivity, but fragment size did appear to affect productivity. Nests had a 9 percent probability of survival in small fragments and a 31 percent probability of survival in large fragments (Winter 1996). In Missouri tallgrass prairie fragments, density increased with decreasing distance among grassland patches (Winter 1998). Nest depredation was higher less than 50 meters from an edge habitat (Winter 1998).
Management Requirements: Burning (Zimmerman 1992), mowing (Swengel 1996), or grazing (Klute 1994, Klute et al. 1997) can provide suitable habitat by controlling succession. Regardless of management treatment, avoid disturbing habitat during the breeding season, which ranges from late April to late August (Gross 1921, 1968; Stewart 1975; Finck 1984). Treatments can occur in early spring (several weeks prior to their arrival on the breeding grounds) or possibly in the fall after the breeding season. Bollinger et al. (1990) suggested maintaining adjacent, untreated areas to provide refuge for fledglings and late-nesting or renesting Bobolinks (DOLICHONYX ORYZIVORUS), a technique that also could be applied for Dickcissels.

BURNING: Petersen (1978) reported that Dickcissels were present in both annually burned and unburned tallgrass prairie in Kansas. Also in Kansas, spring burning had no effect on relative abundance except in drought years, when it had a negative effect (Zimmerman 1992). Abundance was not related to the number of years since the last burning or haying treatment in Kansas (Zimmerman 1993) or Missouri (Swengel 1996, Winter 1998). In Missouri, hayed areas had higher numbers than spring-burned areas or areas that were both hayed and burned (Swengel 1996). In Illinois tallgrass prairie fragments, were present one (1-4 months) and two (13-16 months) growing seasons postburn (Herkert 1994b). In Illinois, Westemeier and Buhnerkempe (1983) found preference for tallgrass areas 3 years postburn. Burning can be used to control woody plant invasion (Eddleman 1974).

HAYING: Haylands with abundant forbs, especially legumes, attract high nesting densities (Ryan 1986, Frawley 1989, Frawley and Best 1991). Mowing can be used to prevent encroachment of woody vegetation; however, annual mowing and mowing during the breeding season, results in very high rates of nest failure (Taber 1947, Ryan 1986, Frawley 1989, Frawley and Best 1991, Igl 1991). Low productivity and low annual return rates in mowed alfalfa fields suggest that these areas are population sinks (Sealy 1976, Igl 1991). In Michigan, breeding activities in hayfields were terminated following mowing (Monroe 1967, Harrison 1974, Harrison and Brewer 1979). In Iowa alfalfa fields, colonized fields after the first mowing during the breeding season, but only after vegetation height was more than 20 centimeters and forb coverage reached about 60 percent (Frawley 1989). Densities never recovered to pre-mowing levels. Igl (1991), however, noted that some alfalfa fields remained undisturbed after mowing for longer periods because of differences in landowners' mowing schedules; consequently, densities in these fields continued to increase and occasionally exceeded pre-mowing levels. In Missouri tallgrass prairie, were more common in conservation-hayed areas (mowed in July) than burned areas (Swengel 1996). In Missouri tallgrass prairie fragments, density increased with the number of years since the last haying treatment (Winter 1998). In Illinois tallgrass prairie, preferred areas that were hayed in mid-July every 2-3 years over idle areas (Westemeier and Buhnerkempe 1983). Nested in tallgrass prairie hay meadows in eastern Kansas (Jensen, pers. comm.).

GRAZING: Used grazed tallgrass areas in Oklahoma (Overmire 1963, Wiens 1973). In Missouri, nested in moderately grazed to idle cover (Skinner et al. 1984). Bock et al. (1993) reported positive response to moderate grazing but negative to heavy grazing in shortgrass prairie. Breeding densities were low in grazed areas in Oklahoma and Illinois, possibly due to direct disturbance by cattle (Gross 1921, Overmire 1963). Eddleman (1974) advocated protection of suitable habitat from grazing in Kansas, where dense cover for nesting is required by the species. Grazing in combination with other management treatments can be particularly detrimental to abundance. In Kansas and Missouri, lower abundance found on areas both grazed and hayed than on hayed areas or areas both burned and hayed (Eddleman 1974, Swengel 1996). Combined grazing and burning of Kansas prairie resulted in lower numbers, lower productivity, and delayed nesting (Eddleman 1974, Zimmerman 1997).

CONSERVATION RESERVE PROGRAM: CRP grasslands provide important breeding habitat in Indiana, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota (Johnson and Schwartz 1993, Patterson 1994, Johnson and Igl 1995, King and Savidge 1995, Hull et al. 1996, Klute 1996, Patterson and Best 1996, Best et al. 1997, Delisle and Savidge 1997, Klute et al. 1997). In Kansas, were common in CRP fields planted to native grasses, with highest abundances occurring in fields with a high frequency of occurrence (more than 60 percent) of forbs (Hull et al. 1996). In Nebraska, preferred unburned and unmowed CRP fields, and fields that were characterized by tall, native grasses with few forbs, deep litter, and residual vegetation (Delisle and Savidge 1997). Preferred structurally complex vegetation was found in CRP fields planted to big bluestem (ANDROPOGON GERARDII), switchgrass (PANICUM VIRGATUM), and Indiangrass (SORGHASTRUM NUTANS) (Delisle and Savidge 1997). Also were found in structurally complex cool-season grasslands of moderately dense brome, with patches of weedy, tall vegetation. In cool-season grasses, where overall vegetation density was low, used areas with dense forbs. Were absent or uncommon in cool-season grasses without tall forbs. In South Dakota, Blankespoor (1980) found use of a restored grassland 2-4 years after it was reseeded to native grasses. Klute (1994) recommended grazing of CRP grasslands in Kansas to increase forb abundance. In North Dakota, were found in dense nesting cover planted to alfalfa/wheatgrass (AGROPYRON SPP.) (Renken and Dinsmore 1987). Low densities sometimes are found in cropland areas that are untilled or under reduced tillage. Nested in low densities in rowcrop fields (corn or soybeans) that were either untilled or under reduced tillage in Iowa (Basore et al. 1986, Bryan and Best 1991).

Population/Occurrence Delineation
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Group Name: Passerines

Use Class: Breeding
Subtype(s): Foraging Area, Nest Site, Nesting Colony
Minimum Criteria for an Occurrence: Evidence of historical breeding, or current and likely recurring breeding, at a given location, minimally a reliable observation of one or more breeding pairs in appropriate habitat. Be cautious about creating EOs for observations that may represent single breeding events outside the normal breeding distribution.

Mapping Guidance: Breeding occurrences include nesting areas as well as foraging areas.

For swallows and other species that have separate nesting and foraging areas, separations are based on nest sites or nesting areas, not to locations of foraging individuals. For example, nesting areas separated by a gap larger than the separation distance are different occurrences, regardless of the foraging locations of individuals from those nesting areas. This separation procedure is appropriate because nesting areas are the critical aspect of swallow breeding occurrences, tend to be relatively stable or at least somwhat predictable in general location, and so are the basis for effective conservation; foraging areas are much more flexible and not necessarily static.

Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Significant dispersal and associated high potential for gene flow among populations of birds separated by tens of kilometers (e.g., Moore and Dolbeer 1989), and increasing evidence that individuals leave their usual home range to engage in extrapair copulations, as well as long foraging excursions of some species, make it difficult to circumscribe occurrences on the basis of meaningful population units without occurrences becoming too large. Hence, a moderate, standardized separation distance has been adopted for songbirds and flycatchers; it should yield occurrences that are not too spatially expansive while also accounting for the likelihood of gene flow among populations within a few kilometers of each other.

Be careful not to separate a population's nesting areas and foraging areas as different occurrences; include them in the same occurrence even if they are more than 5 km apart. Mean foraging radius (from nesting area) of Brown-headed Cowbird females was 4.0 kilometers in California, 1.2 kilometers in Illinois-Missouri (Thompson 1994). Yellow-headed Blackbirds, Brewer's Blackbirds, and probably Red-winged Blackbirds all forage up to 1.6 kilometers away from breeding colony (Willson 1966, Horn 1968). In one study, Brewer's Blackbirds were found as far as 10 kilometers from nesting area (Williams 1952), but this may be unusual.

For swallows and other parrerines with similar behavioral ecology, separation distance pertains to nest sites or nesting colonies, not to locations of foraging individuals. For example, nesting areas separated by a gap of more than 5 km are different occurrences, regardless of the foraging locations of individuals from those nesting areas. This separation procedure is appropriate because nesting areas are the critical aspect of swallow breeding occurrences, tend to be relatively stable or at least somwhat predictable in general location, and so are the basis for effective conservation; foraging areas are much more flexible and not necessarily static.

Be cautious about creating EOs for observations that may represent single breeding events outside the normal breeding distribution.

Unsuitable habitat: Habitat not normally used for breeding/feeding by a particular species. For example, unsuitable habitat for grassland and shrubland birds includes forest/woodland, urban/suburban, and aquatic habitats. Most habitats would be suitable for birds with versatile foraging habits (e.g., most corvids).

Date: 10Sep2004
Author: Hammerson, G.

Use Class: Migratory stopover
Subtype(s): Foraging Area, Roost Site
Minimum Criteria for an Occurrence: For most passerines: Evidence of recurring presence of migrating individuals (including historical) and potential recurring presence at a given location; minimally a reliable observation of 25 birds in appropriate habitat.

For swallows: Evidence of recurring presence of migrating flocks (including historical) and potential recurring presence at a given location; minimally a reliable observation of 100 birds in appropriate habitat (e.g., traditional roost sites).

Occurrences should be locations where the species is resident for some time during the appropriate season; it is preferable to have observations documenting presence over at least 7 days annually.

EOs should not be described for species that are nomadic during nonbreeding season: e.g., Lark Bunting.

Be cautious about creating EOs for observations that may represent single events.

Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Separation distance somewhat arbitrary but intended to define occurrences of managable size for conservation purposes. Occurrences defined primarily on the basis of areas supporting concentrations of birds, rather than on the basis of distinct populations.

For swallows and other species with similar behavioral ecology, the separation distance pertains to communal roost sites rather than to foraging areas; the former tend to be more stable and specific over time than the latter.

Date: 03Sep2004
Author: Hammerson, G., and S. Cannings

Use Class: Nonbreeding
Subtype(s): Foraging Area, Roost Site
Minimum Criteria for an Occurrence: Any area used traditionally in the nonbreeding season (used for populations that are not resident in a location year-round). Minimally, reliable observations of 10 or more individuals in appropriate habitat for 20 or more days at a time. For G1-G3 species, observations of fewer individuals could constitute an occurrence of conservation value. Sites used during migration should be documented under the 'migratory stopover' location use class.

Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Separation distance is necessarily arbitrary but attempts to balance the high mobility of birds with the need for occurrences of reasonable spatial scope. Note that a population's roost sites and foraging areas are parts of the same occurrence, even if they are more than 5 km apart.

For swallows and other species with similar behavioral ecology, the separation distance pertains to communal roost sites rather than to foraging areas; the former tend to be more stable and specific over time than the latter.

Date: 03Sep2004
Author: Hammerson, G.

Use Class: Nonmigratory
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a particular location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals in or near appropriate habitat.

These occurrence specifications are used for nonmigratory populations of passerine birds.

Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Significant dispersal and associated high potential for gene flow among populations of birds separated by tens of kilometers (e.g., Moore and Dolbeer 1989), and increasing evidence that individuals leave their usual home range to engage in extrapair copulations, as well as long foraging excursions of some species, make it difficult to circumscribe occurrences on the basis of meaningful population units without occurrences becoming too large. Hence, a moderate, standardized separation distance has been adopted for songbirds and flycatchers; it should yield occurrences that are not too spatially expansive while also accounting for the likelihood of gene flow among populations within a few kilometers of each other.

Be careful not to separate a population's nesting areas and breeding-season foraging areas as different occurrences; include them in the same occurrence even if they are more than 5 km apart. Blue jays have small summer home ranges but fly up to 4 kilometers to harvest mast (Tarvin and Woolfenden 1999). Flocks of pinyon jays range over 21-29 square kilometers (Ligon 1971, Balda and Bateman 1971); nesting and foraging areas may be widely separated. Tricolored blackbirds forage in flocks that range widely to more than 15 kilometers from the nesting colony (Beedy and Hamilton 1999).

Unsuitable habitat: Habitat not normally used for breeding/feeding by a particular species. For example, unsuitable habitat for grassland and shrubland birds includes forest/woodland, urban/suburban, and aquatic habitats. Most habitats would be suitable for birds with versatile foraging habits (e.g., most corvids).

Date: 10Sep2004
Author: Hammerson, G.
Notes: These specs pertain to nonmigratory species.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 30Nov1999
NatureServe Conservation Status Factors Author: Koenen, M., and D.W. Mehlman
Management Information Edition Date: 15Jun1999
Management Information Edition Author: DECHANT, J.A., M.A. SONDREAL, D.H. JOHNSON, L.D. IGL, C.M. GOLDADE, A.L. ZIMMERMAN, AND B.R. EULISS. REVISIONS BY G. HAMMERSON, M. KOENEN, AND D.W. MEHLMAN
Management Information Acknowledgments: Parts of this abstract were originally researched and written by staff of the Northern Prairie Wildlife Research Center and published as Dechant et al. (1999). Additional support for the preparation of this abstract was provided by the National Fish and Wildlife Foundation's Neotropical Migratory Bird Conservation Initiative, through challenge grant number 97-270 to The Nature Conservancy, Wings of the Americas program. Matching funds for this grant were donated by Canon U.S.A., Inc.
Element Ecology & Life History Edition Date: 16May1996
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

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