Chondestes grammacus (Say, 1823)
Basis for Listing
The Lark Sparrow (Chondestes grammacus) breeds throughout much of the western and central United States into southern portions of Canada and, less commonly, in the eastern U.S.. Breeding Bird Survey trend data (Sauer et al. 2014) for this species show significant declines in some areas, increases in others, with an overall range-wide decline of about 1% annually since surveys began in the late 1960s. Lark Sparrow trends vary in Minnesota’s neighboring states and Canadian provinces. They have shown increases (not statistically significant) in Wisconsin, where they are a species of special concern, and South Dakota. In Iowa, Lark Sparrows have increased significantly in the long-term but have declined in the most recent 10-year period. This species has also shown significant increases in Manitoba. Lark Sparrows are presumably extirpated in Michigan (Michigan Breeding Bird atlases I and II). There have been significant declines in several western states, including California, Idaho, Oklahoma, Oregon, and Texas.
In Minnesota, Lark Sparrows were much more abundant historically. The ornithologist Hatch noted in 1892 that Lark Sparrows occurred in greatest numbers in "…the vicinity of open brush-land with a few deciduous trees not far away." Another early ornithologist, T.S. Roberts, in 1932 stated that the Lark Sparrow was common "…in all the open woodlands, and everywhere on prairie knolls." In 1936, however, Roberts reported that in the last 20-30 years (i.e., early 1900s) Lark Sparrows had suffered one of the greatest reductions in number of any bird in the state. He reported on an observer in the Red Wing area (Goodhue County) finding only 1-2 Lark Sparrows in an area where they had previously found 300 or so within a mile radius.
At the present time, Lark Sparrows occur in low densities from southeastern Minnesota through the Minnesota River Valley and Anoka Sand Plain (North Central Glaciated Plains and Minnesota and Northeast Iowa Morainal sections) and at scattered sites in western Minnesota (Red River Valley Section) extending to the northwestern region Aspen Parklands. While the Minnesota Biological Survey (MBS), Minnesota Ornithologists’ Union (MOU), and Minnesota Breeding Bird Atlas Project (MNBBA) have documented Lark Sparrows from many locations in Minnesota, many of these records are of only one to a few individuals, with unknown persistence over the years. Well-known areas where Lark Sparrows have occurred for many years include some of Minnesota’s highest quality areas of dry prairie and oak savanna.
The vast majority of Minnesota’s oak savanna and dry prairie habitat for Lark Sparrows has already been lost (Minnesota's Remaining Native Prairie). The few high quality remnants of these habitats are at risk due to development pressures, sand and gravel mining, increases in woody vegetation, invasive species, and other factors. Due to its relatively low numbers, patchy distribution, restricted habitat requirements, and limited habitat availability, the Lark Sparrow was designated a species of special concern in Minnesota in 2013.
Lark Sparrows are a relatively large sparrow, with bold facial markings consisting of chestnut patches bordered by black and white. This species has brown upperparts, with light-colored and un-streaked underparts showing a central breast spot. Their tail has prominent white corners (as opposed to the white tail edges of the much more common Vesper Sparrow (Pooecetes gramieus). The Lark Sparrow has a melodious song consisting of a series of trills, clear whistled notes, and buzzes rising and falling in pitch. This species is quite distinctive and is unlikely to be confused with other sparrows.
In Minnesota, Lark Sparrows typically occur in dry grasslands with a specific set of components and characteristics: short and/or sparse grasses (usually native) in areas of sand or gravel soils, with at least some bare ground and widely-scattered or patchy trees. Favored tree species are typically bur oak (Quercus macrocarpa), northern pin oak (Quercus ellipsoidalis), eastern red cedar (Juniperus virginiana), and occasionally jack pine (Pinus banksiana). This combination of habitat features can be found in a variety of native plant communities, including northern dry savanna, southern dry savanna, northern dry-mesic oak woodland, southern dry-mesic oak woodland, northern dry prairie, southern dry prairie, and southern bedrock outcrop. Lark Sparrows may reach their highest abundance in the state in the Minnesota River Valley, where south-facing slopes having a combination of dry grassland openings, pastures, and rock outcrops with frequent bur oak and red cedar provide extensive suitable habitat. While Lark Sparrows are typically associated with native plant communities, they can sometimes be found in disturbed or human-altered habitats as long as short grass, scattered trees, and sandy soils are present. Pastures, gravel pits, restored prairie-savanna, brushy fence lines, and similar areas all may provide habitat for Lark Sparrows.
Biology / Life History
The Lark Sparrow is a short-distance migrant wintering in Mexico. During courtship displays, the male struts on the ground with its tail cocked at a 45 degree angle. The species usually builds its nest on the ground, rarely in a shrub or small tree. Typically 4-5 eggs are laid then incubated by both the female and male. The young hatch after 11-12 days, are fed by both adults, and then fledge about ten days later. Lark Sparrows eat seeds much of the year; however, insects are eaten and fed to young during the nesting season.
Conservation / Management
The vast majority of native savanna, oak woodland, and dry prairie habitats in Minnesota have been lost by direct conversion to other land uses (Minnesota’s Remaining Native Prairie). Historically, these habitats were maintained by fires, so the suppression/cessation of this natural disturbance in many remaining areas has resulted in sites becoming overgrown by trees and shrubs to the point of no longer providing suitable Lark Sparrow habitat. This is particularly true in the greater Twin Cities metropolitan area, much of which was once savanna or open oak woodland. Prescribed burning can be difficult, if not impossible, close to developed areas, so that this management tool is no longer an option. Sand and gravel mining has resulted in the destruction of Lark Sparrow habitat in many areas and continues to be a threat to remnant prairie and savanna.
Since a relatively narrow set of characteristics make up the grassland component of Lark Sparrow habitat, not all grasslands are suitable. Tall thick grasses such as non-native brome as well as dense stands of native species are usually not suitable for Lark Sparrows. In some cases, grazing at a moderate level can maintain grass at proper levels, but intensive grazing may not provide suitable cover. In areas where oak savanna or woodland has become overgrown with woody vegetation to the point of being unsuitable habitat for Lark Sparrows, restoration of the open character of woodlands, with larger prairie openings, would improve habitat. Prescribed burning can be an important management tool in areas where it can safely be implemented both for reducing woody cover and maintaining or enhancing suitable grassland vegetation.
Conservation Efforts in Minnesota
Surveys by the Minnesota Department of Natural Resources’ Minnesota Biological Survey along with numerous records from Minnesota birders and the MNBBA have provided a good picture of the overall breeding distribution of Lark Sparrows in Minnesota. Still lacking though, is knowledge of populations and relative breeding success in various regions/sites/habitats. The Lark Sparrow is not encountered in high enough numbers on either U.S. Breeding Bird Survey or MNBBA routes to allow statistically significant trend data.
Protection, management, and/or restoration of dry prairie and oak savanna in Minnesota is a relatively high priority, as high quality examples of these native habitats are rare. While such efforts are not being done specifically to manage for Lark Sparrows, this species should respond favorably.
Steven P. Stucker (MNDNR), 2018
(Note: all content ©MNDNR)