Breeding Habitat:Grassland
Nest Type:Open-cup nesting passerine
Migration Status:Neotropical migrant
Nest Location:Ground-low nesting
Grasshopper Sparrows are widespread occupants of grassland habitats across North America. They are found in a variety of tall- and mixed-grass habitats including native prairies, hayfields, pastures, and grassy fallow fields. Their breeding distribution has undergone some dramatic changes during historic times, particularly an eastward range expansion during the nineteenth and early twentieth centuries as deforestation increased the availability of suitable habitats (Andrle and Carroll 1988, Brewer et al. 1991). In recent decades, however, this sparrow has experienced population declines throughout most of its breeding range (Brauning 1992, Brewer et al. 1991, Garrett and Dunn 1981).
Along BBS routes, Grasshopper Sparrows remain most numerous on the Great Plains from North Dakota south to Kansas and the Texas panhandle area, and eastward into portions of Missouri and Iowa (Relative Abundance Map). Population declines prevail throughout most of this range, although some local increases are evident in the Pacific coastal states (Trend Map). During 1966-1994, significant declines occur in 18 states/provinces, 16 physiographic strata, all 3 BBS regions, U.S., and survey-wide. Increases are limited to 3 states and 2 strata (Trend List). Trends during the 1966-1979 and 1980-1994 intervals are similar, with declines substantially outnumbering increases in the states/provinces and strata. All significant regional trends are declines during both intervals. The only encouraging note from the latter period is the fact that there are fewer significant trend estimates, although most trends remain in a negative direction.
The survey-wide indices indicate a fairly consistent decline since the mid-1960s (Survey-wide Annual Indices). All regional trends are similar, as are the trends in a few states such as Michigan (Michigan Annual Indices). However, in many eastern states and strata, the greatest declines occur prior to the early 1980s, followed by slight declines or fairly stable trends. Examples include trends in Indiana, Maryland, New York and Wisconsin (Indiana Annual Indices). (Maryland Annual Indices). (New York Annual Indices) (Wisconsin Annual Indices). The temporal patterns in trends are more variable on the Great Plains. In Kansas, population declines are most evident between the late 1970s and mid-1980s, while in Colorado the declines largely occur prior to the late 1970s (Colorado Annual Indices) (Kansas Annual Indices). In the High Plains Border stratum (S34), the indices are variable but fairly stable (High Plains Border Annual Indices). Where populations are increasing in the western states, these trends have been fairly consistent throughout the survey period as exemplified by the indices for California and the Columbia Plateau stratum (S89) (California Annual Indices) (Columbia Plateau Annual Indices).
Except when the males are singing, Grasshopper Sparrows tend to be very secretive and spend most of their time skulking through grassy cover. They are readily overlooked on CBCs, when this species is recorded in small numbers throughout its winter range across the southern U.S. These limited data are generally insufficient to definitely establish winter population trends.
As is true for most grassland birds, habitat loss is the factor primarily responsible for the recent declines in Grasshopper Sparrow populations. In the northeastern states, the abandonment of farmlands and subsequent reforestation has caused the greatest loss of suitable breeding habitats (Andrle and Carroll 1988, Laughlin and Kibbe 1985). Elsewhere, urbanization and the conversion of grasslands to cultivated crops are the most important factors (Garrett and Dunn 1981, Peterjohn and Rice 1991). Additionally, the early cutting of hayfields can result in the abandonment of breeding territories and contribute to the annual fluctuations in abundance in some areas (Smith 1963).
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birds in New York State. Cornell Univ. Press, Ithaca, NY.
551 pp.
Brauning, D.W., ed. 1992. Atlas of breeding birds in Pennsylvania.
Univ. of Pittsburgh Press, Pittsburgh, PA. 484 pp.
Brewer, R., G.A. McPeek, and R.J. Adams, Jr., eds. 1991. The
atlas of breeding birds of Michigan. Michigan State Univ.
Press, East Lansing, MI. 594 pp.
Garrett, K., and J. Dunn. 1981. Birds of southern California:
status and distribution. Los Angeles Audubon Soc., Los
Angeles, CA. 408 pp.
Laughlin, S.B., and D.R. Kibbe, eds. 1985. The atlas of breeding
birds of Vermont. Univ. Press of New England, Hanover, NH.
456 pp.
Peterjohn, B.G., and D.L. Rice. 1991. The Ohio breeding bird
atlas. Ohio Dept. Natur. Resour., Columbus, OH. 416 pp.
Smith, R.L. 1963. Some ecological notes on the Grasshopper
Sparrow. Wilson Bull. 75:159-165.