Nest Type:Open-cup nesting passerine
Migration Status:Short distance migrant
Nest Location:Ground-low nesting
The western counterpart of the Eastern Meadowlark, the Western Meadowlark is a conspicuous and abundant resident of grasslands, croplands, weedy fallow fields, roadsides, and mixed grasslands/shrublands of central and western North America. Where the two species are sympatric, they are frequently found together in the same fields but Westerns tend to prefer drier and more open habitats with shorter vegetation while Easterns are found in more mesic microhabitats with denser vegetation (Lanyon 1956).
The status and distribution of Western Meadowlarks has remained fairly constant during historic times. The only significant change occurred during the twentieth century when its breeding range expanded eastward into the Great Lakes region (Lanyon 1956, DeVos 1964). This expansion was most apparent during the 1930s, when breeding populations became established in Michigan, western Ohio, and southwestern Ontario (Brewer et al. 1991, Cadman et al. 1987, Peterjohn and Rice 1991). These populations flourished for several decades, but have noticeably declined during recent years.
Western Meadowlarks remain numerous throughout western and central North America from Washington and the prairie provinces south to the southwestern deserts, and east to Iowa and Minnesota (Relative Abundance Map). As is true for many grassland birds, their population trends have generally declined since 1966. Over the entire survey period (1966-1994), Western Meadowlarks have increased only in the Chihuahuan Desert stratum (S56) but declined in 10 states/provinces, 11 physiographic strata, the Eastern and Western BBS regions, U.S., Canada, and survey-wide (Trend List). Declining trends also prevail during the 1966-1979 and 1980-1994 intervals, although the regional trends tend to be slightly less negative after 1980. The trend map shows declines throughout most of its range, but increases are evident from southern California across the southwestern states to Texas and locally on the Great Plains (Trend Map).
Western Meadowlark populations frequently exhibit marked annual fluctuations in response to changing precipitation levels (Andrews and Righter 1992, Phillips et al. 1964). These fluctuations are evident in the BBS annual indices, and tend to obscure some temporal patterns in the population trends. The survey-wide indices are somewhat variable but with a declining tendency (Survey-wide Annual Indices). The declining populations are most apparent in the Eastern BBS Region, particularly in Illinois and Wisconsin where declines have been apparent since the mid-1960s (Illinois Annual Indices) (Wisconsin Annual Indices) (Eastern BBS Region Annual Indices). Declines in the Western BBS Region have generally occurred since the mid-1970s, while populations in the Central BBS Region are variable but relatively stable (Central BBS Region Annual Indices) (Western BBS Region Annual Indices). The annual variability in the indices is more apparent at the scale of states/provinces and strata. The Western Meadowlark population in Iowa is almost cyclical, with peaks at 8-10 year intervals since 1966 (Iowa Annual Indices). Similar temporal patterns are not repeated elsewhere. In California, populations noticeably declined during 1985-1989 followed by a recovery (California Annual Indices). In Alberta, the populations reached several peaks after 1966 followed by marked declines (Alberta Annual Indices). The Colorado indices are indicative of many western states/provinces with highly variable counts but little temporal consistency to the overall trends (Colorado Annual Indices). In North Dakota, Western Meadowlark populations have increased since 1984 (North Dakota Annual Indices).
Population trends on CBCs are similar, with declines apparent throughout most of its range. During the winter months, Western Meadowlarks tend to be most numerous from northern California, Colorado, and southern Nebraska south into Mexico.
Factors responsible for the recent declines are poorly understood, although loss of suitable habitats may be important in most areas. Extensive droughts during the 1930s may have contributed to the eastward range expansion by Western Meadowlarks, but the causes for this expansion and subsequent decline have never been fully explained (Lanyon 1956).
Andrews, R., and R. Righter. 1992. Colorado birds. Denver Mus. Natur. Hist., Denver, CO. 442 pp. Brewer, R., G.A. McPeek, and R.J. Adams, Jr. 1991. The atlas of breeding birds of Michigan. Michigan State Univ. Press, East Lansing, MI. 594 pp. Cadman, M.D., P.F.J. Eagles, and F.M. Helleiner, eds. 1987. Atlas of the breeding birds of Ontario. Univ. of Waterloo Press, Waterloo, ON. 617 pp. DeVos, A. 1964. Range changes of birds in the Great Lakes region. Am. Midl. Natur. 71:489-502. Lanyon, W.E. 1956. Ecological aspects of sympatric distribution of meadowlarks in the north-central states. Ecology 37:98- 108. Peterjohn, B.G., and D.L. Rice. 1991. The Ohio breeding bird atlas. Ohio Dept. Natur. Resour., Columbus, OH. 416 pp. Phillips, A., J. Marshall, and G. Monson. 1964. Birds of Arizona. Univ. of Arizona Press, Tucson, AZ. 212 pp.