With its distinctive black hood and whistled song, the Harris’s Sparrow is a conspicuous summer resident of the transition zone between the subarctic boreal forest and Low Arctic tundra of northern Canada. This species was first collected in Missouri in 1834 by Thomas Nuttall and later named by Audubon for Edward Harris (1799–1863), a companion of Audubon’s on his 1843 trip up the Missouri River ( Baumgartner 1968a , Choate 1985 ). As a breeding species, the Harris’s Sparrow occupies a somewhat restricted range in northern Canada and it overwinters in the south-central plains of the United States (see Figure 1). This sparrow's remote breeding habitat and secretive nesting behavior made it one of the last passerines in North America to have its nest and eggs described. George M. Sutton described his discovery of the Harris's Sparrow nest in 1931: “as I knelt to examine the nest a thrill the like of which I had never felt before passed through me.....at my fingertips lay treasurers that were beyond price” ( Sutton 1936a ).
Like its well-known and widely distributed congeners, the White-throated (Zonotrichia albicollis) and White-crowned (Z. leucophyrs) sparrows, the Harris's Sparrow is a large seed-eating, ground-dwelling emberizid. Comparison of these congeners shows different patterns of plumage with regard to sexual, age and individual variation. Like the others, the Harris’s Sparrow is largely sexually monochromatic but it has tremendous variability in the pattern of black spotting on the breast. Similar to the White-crowned Sparrow, there are basic differences in adult and first-year plumages with generally paler head coloration and less black on the throat and breast in juveniles; however, all age classes show individual variation in breast spotting. These plumage patterns have been studied in the context of social flocks for their use in communication and signaling. Regardless of age or sex, the dark crown, breast spots, and pink bill easily separate the Harris's Sparrow from other Zonotrichia.
Only a handful of scientists have studied the Harris's Sparrow. Prior to breeding studies by Norment that began in 1992, little was known about even the most basic aspects of its breeding biology. Despite this research, there are still no population estimates based on surveys conducted on the breeding grounds. Overwintering populations monitored via the Christmas Bird Count show significant downward trends since the 1970s. Climate change effects on the northern edges of the boreal forest and logging of boreal forest may affect breeding habitats of this species. Further, habitat loss associated with agricultural intensification on the overwintering grounds could also influence populations. The highest research priority for the Harris's Sparrow is to determine the cause(s) of its apparent decline.