Breeding Habitat:Grassland
Nest Type:Open-cup nesting passerine
Migration Status:Short distance migrant
Nest Location:Ground-low nesting
A widespread occupant of open habitats across North America, Horned Larks prefer areas with sparse vegetation and exposed soil. In eastern North America, most pairs occupy tilled fields, overgrazed pastures, the grassy fields bordering airports, and similar habitats although they are occasionally found in vacant lots within cities (Brauning 1992, Peterjohn and Rice 1991). On the Great Plains, they prefer agricultural fields and short-grass prairies. In western North America, this species is associated with desert brushlands, grasslands, and similar open habitats, as well as alpine meadows (Andrews and Righter 1992, Garrett and Dunn 1981). Throughout their range, Horned Larks avoid all habitats dominated by dense vegetation and become scarce and locally distributed in heavily forested areas.
Breeding Horned Larks have not always had such a widespread distribution on the continent. Their breeding range expanded eastward from the Great Plains during the nineteenth century as the forests were cleared. They reached the Atlantic coast before the turn of the century (Brauning 1992, Laughlin and Kibbe 1985). They continued to spread southward into the 1940s (Odum and Burleigh 1946), when populations in the northeastern states were beginning to decline.
Regularly encountered along BBS routes across the United States and southern Canada, Horned Larks are abundant from the Great Plains westward except for the Pacific northwest (Relative Abundance Map). They are also numerous in the midwestern states from the Till Plains eastward across the Great Lakes, but tend to be least numerous in the eastern portion of their range. Note that the BBS provides no information on populations breeding in northern Canada and Alaska.
BBS data indicate that the population declines of the 1940s in eastern North America have become more widespread in recent decades. The trend maps indicate a range-wide decline in the Horned Lark populations (Trend Map). Local increases prevail only in the vicinity of the western Great Lakes and northern Great Plains. During the entire survey period (1966-1994), increases occur in only 2 states/provinces and 2 physiographic strata as opposed to declines in 18 states/provinces, 16 strata, the Western BBS Region, United States, Canada, and survey-wide (Trend List). Declines greatly outnumber increases in the states/provinces and strata during the 1966-1979 and 1980-1994 intervals. Regional trends during these intervals are generally in a negative direction.
The survey-wide indices exhibit a general decline since the mid- 1960s (Survey-wide Annual Indices). The indices for states/provinces and strata tend to be quite variable with large annual fluctuations in abundance. However, there is no consistent temporal pattern to the declines in various portions of the continent. Some populations have declined throughout the survey period, such as those in Missouri and Texas (Missouri Annual Indices) (Texas Annual Indices). In Iowa, Kentucky, and other states, the declines are most prevalent prior to the mid-1970s with only gradual declines during subsequent years (Iowa Annual Indices) (Kentucky Annual Indices). In Saskatchewan, the population decline mostly occurred after 1980, while in Manitoba, the decline was most prevalent through the mid- 1980s (Manitoba Annual Indices) (Saskatchewan Annual Indices). In the few areas where populations are increasing, such as the Great Plains Roughlands (S39) stratum, the indices are variable but show a general increasing tendency since the mid-1960s (Great Plains Roughlands Annual Indices).
Wintering Horned Larks are also regularly encountered in large numbers on CBCs, where they are most abundant from the Great Plains westward to the eastern edge of the Cascade and Sierra mountain ranges. Trends based on CBC data are similar to the BBS trend estimates. Significant declines outnumber increases, and decreasing populations are scattered throughout their range.
While the loss of agricultural fields to reforestation and development have contributed to the population declines in eastern North America (Buckelew and Hall 1994, Laughlin and Kibbe 1985), the factors responsible for their declines in other portions of North America are poorly understood. Habitat loss is a factor in southern California (Garrett and Dunn 1981), and may be involved in declines in other areas with rapidly expanding human populations. However, the varied temporal patterns shown by the declining populations may indicate that multiple factors are responsible for these survey-wide trends.
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atlas. Ohio Dept. Natur. Resour., Columbus, OH. 416 pp.