Northern Prairie Wildlife Research Center
In the early 1900s, vesper sparrows were common summer residents throughout Ohio. Vesper sparrows began declining in the western and central parts of the state during the 1930s as agricultural land-use intensified. Lower numbers in unglaciated Ohio were first noticed during the 1960s as abandoned farmland reverted to forest, decreasing nesting habitat. Today, vesper sparrows are fairly common summer residents in western Ohio through Huron, Richland, Knox, Licking, Pickaway, Ross, Highland, and Brown counties. In southern Ohio, vesper sparrows are locally common only on reclaimed surface mines (Peterjohn 1989, Peterjohn and Rice 1991).
Most spring migrants return to Ohio during April. Nests with eggs have been reported the last week of April, but most first clutches are laid in mid-May. Most fledglings are detected in mid-June. Vesper sparrows are frequently double-brooded. Second clutches may be noted through mid-July and adults accompanied by fledglings through August. Most vesper sparrows depart between 15 September and 20 October for wintering grounds in the southeastern United States. The number of winter records has averaged 1 sighting every 2 years since the mid 1960s (Peterjohn 1989, Peterjohn and Rice 1991).
Vesper sparrows are birds of Ohio's farmlands. They are frequently encountered along fencerows bordering cultivated fields, pastures, and meadows (Peterjohn 1989, Peterjohn and Rice 1991). Rodenhouse and Best (1983) stated that vesper sparrows in the Midwest depend on rowcrops and adjacent uncultivated habitats for all their breeding requisites. In intensively farmed regions, vesper sparrow nests were found in cultivated corn and soybean fields (Dambach and Good 1940; Good and Dambach 1943; Graber and Graber 1963; Bent 1968; Rodenhouse and Best 1983, 1994; Best and Rodenhouse 1984; Wooley et al. 1985; Basore et al. 1986; Sample 1989; Bryan and Best 1991), no-tillage corn and soybean fields (Wooley et al.1985, Basore et al. 1986), fencerows bordering rowcrops (Rodenhouse and Best 1983, Best and Rodenhouse 1984, Basore et al. 1986), grassed waterways in rowcrop fields (Rodenhouse and Best 1983; Bryan and Best 1991,1994), washes (i.e., cultivated watercourse where erosion severely stunted crop and weed growth) (Rodenhouse and Best 1983), and weedy areas (i.e., low wet areas where crop growth was stunted by flooding or rank weed growth) (Rodenhouse and Best 1983). Other agricultural habitats used by vesper sparrows for nesting included small grains (Dambach and Good 1940, Graber and Graber 1963, Sample 1989, Hartley 1994), hayfields (Good and Dambach 1943, Bent 1968, Wiens 1969, Frawley and Best 1991), meadows (Dambach and Good 1940, Reed 1986), pasture (Good and Dambach 1943, Graber and Graber 1963, Bent 1968, Wiens 1969), and CRP grasslands (Johnson and Schwartz 1993a,b; Reynolds et al.1994; Swanson et al.1995). Vesper sparrow nests also were found in sagebrush grassland (Walcheck 1970, Best 1972, Schaid et al. 1983, Wiens and Rotenberry 1985), reclaimed surface mines (Whitmore and Hall 1978, Wray and Whitmore 1979), old fields (Graber and Graber 1963, Berger 1968, Sample 1989), railroad rights-of-way (Braband 1984), roadside rights-of-way (Warner 1992, Camp and Best 1994), and native and restored tallgrass prairie (Blankespoor 1980, Sample 1989, Volkert 1992, Hartley 1994). Nesting densities of vesper sparrows were lowest in corn, soybeans, and small grains (3-11 nests/40 ha; Good and Dambach 1943, Rodenhouse and Best 1983), higher in reclaimed surface mine (18-19 nests/40 ha; Wray et al.1982), and highest in undisturbed grassland and old field communities (12-86 nests/40 ha; Berger 1968, Best 1972).
Wiens (1969) reported that vesper sparrows occupied the most xeric, sparsely vegetated sites of all grassland birds studied. He found vesper sparrow nests in areas with sparse vegetation of low height, low vertical vegetation density, and low litter depth. Vesper sparrow nesting territories on his study area had an average of 74% grass cover, 23% forb cover, 2% bare ground, and 52-cm herbaceous canopy height. In another Wisconsin study, Sample (1989) reported that mean vegetative characteristics of habitats used by nesting vesper sparrows were 4% woody cover, 68% herbaceous vegetation cover, 17% litter cover, 13% bare ground, 62-cm maximum vegetation height, and 21-cm vegetation height-density. Reed (1986) found vesper sparrows using habitats with 88% herbaceous cover (36% grass and 52% forb), 12% bare ground, and 20-cm mean herbaceous canopy height. Nest sites (n = 39) of vesper sparrows in West Virginia were characterized by 23% grass cover, 24% forb cover, 39% bare ground, 3-cm litter depth, and 46-cm mean herbaceous canopy height (Wray and Whitmore 1979). Vesper sparrow nest sites in no-tillage crop fields had an average of 69% residue cover and 31% bare ground (Basore et al. 1986).
Several studies noted that vesper sparrows typically nested in dry, sparsely vegetated areas (Sutton 1959, Berger 1968, Wiens 1969, Owens and Myres 1973, Whitmore and Hall 1978, Whitmore 1979b, Basore et al.1986, Perritt and Best 1989, Sample 1989) and avoided areas with tall, dense vegetation (Graber and Graber 1963, Reed 1986, Sample 1989). Along roadsides in Iowa, vesper sparrows placed their nests in shorter, sparser vegetation than was available on the roadside overall (Camp and Best 1994). An inverse correlation between vesper sparrow abundance and vegetation density and/or percent cover was reported in several studies (Whitmore 1979b, Rodenhouse and Best 1983, Sedgwick 1987, Frawley and Best 1991, Camp and Best 1994). In Wisconsin, vesper sparrow density was negatively correlated with vegetation height-density and percent standing residual vegetation cover and positively correlated with percent bare ground (Sample 1989). Wiens and Rotenberry (1985) reported a significant decrease in vesper sparrow abundance as grass cover increased from 1-4% to 10-57% and shrub cover decreased from 19-24% to 4-12%. On reclaimed surface mines in West Virginia, vesper sparrow reproductive success was positively related to percent litter cover and vertical vegetation density and negatively associated with percent bare ground around the nest (Wray and Whitmore 1979). Wray and Whitmore (1979) found that successful vesper sparrow nests had higher values of percent litter cover and vertical vegetation density but lower values for bare ground than unsuccessful nests, even though vegetation within all vesper sparrow nesting territories was characterized by low vertical density, low litter cover, and a large amount of bare ground. Rotenberry and Wiens (1980) found vesper sparrow nesting densities positively associated with percent forb cover.
Sample (1989) believed that vesper sparrows required fairly tall woody vegetation for singing and courting. Most vesper sparrow territories were situated along fencerows (Rodenhouse and Best 1983, Best and Rodenhouse 1984), along field borders (Whitmore and Hall 1978), or in fields with widely scattered shrubs and trees (Wiens 1969, Kantrud and Kologiski 1982). Elevated song perches (e.g., fencerows, trees bordering fields, and shrubs) were considered territory requisites. Fencerow removal dramatically reduced the proportion of corn and soybean fields used by vesper sparrows for nesting (Best 1983). Rodenhouse and Best (1983) reported that vesper sparrow nesting densities were highest in crop fields bordered by fencerows with a large amount of tree and shrub cover. They recommended increasing the tall woody component (trees and shrubs) of fencerows to increase vesper sparrow nesting densities in adjacent rowcrop fields. In North Dakota, vesper sparrow nesting densities were higher in pastures with scattered shrubs than in those without shrubs (Kantrud and Kologiski 1982).
Vesper sparrows concentrated their foraging activities in areas with sparse vegetation (Reed 1986, Perritt and Best 1989, Rodenhouse and Best 1994). Wiens (1969) reported that all observed vesper sparrow foraging occurred in very low (0-5 cm tall) grassy cover. Early in the nesting season, when insects were rapidly colonizing young crops, vesper sparrows walked along rows and gleaned insects from plants and low foliage (Rodenhouse and Best 1994). Most vesper sparrows were observed foraging in or near (<10 m) uncropped or weedy areas (fencerows, grassed waterways, and washes) later in the season as crop canopies closed (Rodenhouse and Best 1994).
Vesper sparrow nestlings were fed a predominately animal diet, primarily insects, the most important being Coleoptera, Orthoptera, Hemiptera, Homoptera, and Hymenoptera (Evans 1964). Adults fed on both animal and plant materials throughout the breeding season, seeds of Panicum, Danthonia, and Cyperus being most important in cultivated and uncultivated habitats (Evans 1964).
Frequent agricultural operations reduced nest success of vesper sparrows in corn and soybean fields (Perritt and Best 1989), accounting for 27% of all nest losses (Best 1983). Vesper sparrow production in rowcrops was enhanced by no-tillage agriculture because the reduction in tillage operations substantially decreased the number of nests destroyed (Rodenhouse and Best 1983). However, vesper sparrow reproductive success in cultivated and no-tillage rowcrop fields was below levels necessary to offset adult mortality (Rodenhouse and Best 1983, Basore et al. 1986).
Bryan and Best (1994) reported that the probability of encountering a vesper sparrow nest was 6 times higher in mowed (cut after 1 Aug) compared to unmowed grassed waterways. Vesper sparrows placed their nests in the swath of short, sparse vegetation on mowed roadsides in Iowa (Camp and Best 1994).
Herkert et al. (1993) concluded that moderate grazing, leaving 20-40% vegetative cover greater than or equal to 25 cm tall, benefited grassland birds that prefer low vegetation height and density like the vesper sparrow. In South Dakota, Huber and Steuter (1984) found vesper sparrow nests in lightly-grazed areas. Kantrud and Kologiski (1982) reported that heavy grazing did not depress vesper sparrow nesting densities in North Dakota.
Herkert (1991) reported that vesper sparrow abundance was higher on recently burned (first growing season post-fire) grasslands than on those in their second or more growing season post-fire. Huber and Steuter (1984) found vesper sparrows nesting only on unburned grasslands in South Dakota and concluded that they avoided burned areas.
Vesper sparrows were encountered on habitat blocks of all sizes in Illinois and Missouri and were, therefore, considered highly tolerant of habitat fragmentation (Herkert et al.1993). Herkert (1991) considered <10 ha the minimum area requirement of vesper sparrows in Illinois. In Missouri, Samson (1980) estimated that 10-100 ha was the minimum amount of contiguous grassland habitat required to maintain a viable breeding population of vesper sparrows. In Maine, vesper sparrow incidence increased with grassland area and reached 50% at about 20 ha (Vickery et al. 1994). In Ohio, 3 CRP grasslands occupied by vesper sparrows averaged 10 ha and ranged from 5 to 15 ha (Oh. Div. Wildl., unpubl. data).