Courtesy Kenn Kaufman
As southeastern pine woods continue to shrink or be altered by commercial farming, Bachman's Sparrow retreats south and east into forest fragments. Endemic to the United States, it breeds and winters from Arkansas south into East Texas and then eastward to the Carolinas and Florida. Christmas Bird Counts indicate a withdrawal from the northern part of the breeding range in winter. In the early 2000s, breeding appeared most dense in Florida and south-central Alabama. As Americans left their farms for cities at the turn of the 19th Century, Bachman's Sparrow occupied the re-growing pine forests, and its range expanded northward from southern Oklahoma to southwestern Pennsylvania. The expansion was largest between 1915 and 1920. Bachman's Sparrow is now practically absent from states like Illinois and Ohio.
Primarily, Bachman's Sparrow occupies open pine woods with a grassy floor, but can sometimes use oak-palmetto scrub and open spaces that are in transition to forest (replanted clearcuts, powerline cuts, and abandoned fields). Important understory components include grasses (wiregrass, panic grass, little blue stem, broom sedge), palmetto, leaf litter, and open ground. Frequent and brief natural fire maintains this habitat best. Even fairly small patches (7-140 acres) of suitable habitat may be occupied. All of its closest relatives, like the Cassin's Sparrow, are grassland species.
Walking and hoping on the ground, Bachman's Sparrow methodically searches the forest floor and leaf litter for seeds and insects. Food items are plucked from surfaces (gleaning) and snatched from the air in short hops. The diet appears to shift with the seasons. The insect diet includes beetles (many weevils), caterpillars, crickets, grasshoppers, leafhoppers, and wasps. This songbird consumes the seeds of grasses (panic and bristle), pines, sedges, and blueberries. Natural, frequent fire appears to increase the insect prey favored by the Bachman's Sparrow.
Monogamous pairs of Bachman's Sparrows probably form before territories are established in late March and early April, and they may be maintained for more than one season. Males sing vigorously from low, exposed perches, but territories may otherwise be poorly defended. Most pairs successfully raise two broods. Next to a tussock of grass or some other low vegetation, the female constructs a nest cup by herself in a scraped depression, usually covers it with a dome, and lines it with animal hair and fine grass pieces. Nests are made of grass parts, weed stems, and small roots.
The female incubates 3-5 whitish eggs for about 13 days, while the male keeps his distance and sings. The hatchlings are mostly naked, completely blind, and helpless. Both parents provision the young with small insects and remove fecal sacs from the nest, until the young fledge in about 10 days. Twenty-five days later, most juvenile Bachman's Sparrows leave the territory, and they attain adult size at about five weeks of age. The pair take a break, a little less than two weeks, before starting the second nest.
The migratory behavior, routes, and exact timing are poorly documented for Bachman's Sparrow. Southern populations apparently do not migrate. In the fall, northern populations probably migrate between late August and late October. For them, spring migration is fairly early, with first arrival dates ranging between late March and early April. Since this songbird has withdrawn from much of its northern range, the extent of its migration is now even more unclear.