Montana Field Guide

The Nelson's Sparrow is a small sparrow averaging about 5 inches in length. Adults of both sexes are similar in appearance with males larger on average than females. The eyebrow and malar stripe are an obvious orange-buffy color, sharply defined. The ear coverts are gray and the crown is gray striped with brown borders streaked with black. The upperparts are a rich olive-brown and the back is dark with distinct white streaks. The tail is brown and sharply tapered. The breast, flanks and sides are buffy-orange and the abdomen is white. The flanks are faintly streaked and the central breast is unstreaked. The juvenile is similar to the adult in appearance except the crown and ear coverts are brownish rather than gray (Greenlaw and Rising 1994).

For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.

Nelson's Sparrows have no central stripe on their dark crown. This characteristic can distinguish Nelson's from similar Le Conte's Sparrows, which do have a distinct pale, central stripe. Another characteristic separating these two species is the lack of striping on the side neck and nape of the Nelson's Sparrow (Greenlaw and Rising 1994).

The migratory pattern of this species in Montana is poorly known. A general lack of observations limits any educated guess about their migratory pathway within the state. Only 5 observations have been made regarding Nelson's Sparrows during migration in Montana (Montana Bird Distribution Committee 2012). Four observations were recorded in May and June and 1 was recorded in August. All observations were made in Sheridan County, Montana where this species is known to occur and breed.

There is very little information about the habitat for this species in Montana, however it is assumed that the habitat is similar to that used in other portions of the species' range. This species prefers freshwater wetlands with dense, emergent vegetation or damp areas with dense grasses (Bownan 1904, Murray 1969, Stewart 1975, Krapu and Green 1978, Knapton 1979, Williams and Zimmer 1992, Berkey et al. 1993). In North Dakota, Nelson's Sparrows were common in Prairie Cordgrass (Spartina pectinata) stands, occurred at the edges of Common Reed (Phragmites australis) stands, and nested in sprangletop (Murray 1969). In northeastern North Dakota, they nested in thin, sparse grass on a wet alkali flat (Rolfe 1899, Hill 1968).

Nests usually are built in stands of grasses with litter that is persistent from year to year (Greenlaw and Rising 1994). Nests are built on or slightly above the ground in damp areas among emergent vegetation (Murray 1969, Stewart 1975). In North Dakota, Nelson's Sparrows are more abundant in dry years than in wet years (Stewart 1975). In dry years, they nest in the shallow-marsh and deep-marsh zones of wetlands. In wet years, they nest in cordgrass (Spartina spp.) within wet-meadow zones.

Food habits information on Nelson's Sparrow is currently unavailable in the state. Information from other areas of the species' range reveal that Nelson's Sharp-tailed Sparrows eat insects, spiders, amphipods, and other small invertebrates, supplemented in the colder months by seeds and grains. They glean food from ground or from grass stems.

No ecological information regarding Nelson's Sparrows exists for Montana. In general, Nelson's Sparrows nest in colonies and may be non-territorial (Murray 1969, Greenlaw and Rising 1994). However, they do respond to recorded playbacks of songs, which suggests some territoriality (D. R. C. Prescott, personal communication). They are interspecifically territorial with Le Conte's Sparrows (Ammodramus leconteii) (Murray 1969, D. R. C. Prescott, personal communication).

It is believed that this species breeds in the state on an annual basis. However, only a single breeding occurrence from 1995 is documented. This observation indicates a brood fledged in August 1995 from extreme eastern Sheridan County near Round Lake. Other observations of singing males have been documented in the vicinity and surrounding area, but no direct evidence of breeding was noted.

No other information on species' reproduction in Montana has been recorded. Information from other portions of the species' range indicates that eggs are laid mostly in late spring and early summer. Clutch size is three to seven (usually three to five). Commonly two broods per year are produced. Incubation lasts about 11 days and is performed by the female alone. Young are tended by the female and leave the nest at 10 days but they are dependent on the female for about 20 days more.

No known active management is ongoing for Nelson's Sparrows in the state. Conservation Reserve Program practices may provide large blocks of suitable habitat for this species in northeastern Montana.