Savannah Sparrow

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Common Name: Savannah Sparrow
Scientific Name: Passerculus sandwichensis

Size: 4.3-5.9 inches (11-15 cm)

Habitat: North America; it breeds in Alaska, Canada, northern, central and Pacific coastal USA, Mexico and Guatemala. The Pacific and Mexican breeders are resident, but other populations are migratory, wintering from the southern United States across Central America and the Caribbean to northern South America. It is a very rare vagrant to Western Europe.

On both their summer and winter ranges, Savannah Sparrows live in grasslands with few trees, including meadows, pastures, grassy roadsides, sedge wetlands, and cultivated fields planted with cover crops like alfalfa. Near oceans, they also inhabit tidal saltmarshes and estuaries. In Alaska and northern Canada, they live among the shrubby willows of the tundra.

Status: Least Concern. Global Population: Unknown amount of mature individuals. Savannah Sparrows are widespread and abundant, although the Breeding Bird Survey indicates their numbers have declined in the last half-century in parts of the U.S. and Canada. They likely benefited greatly from human changes to landscapes early in the twentieth century that cleared forests and opened up pasturelands, but then they may have lost ground to the urbanization that followed—and to shifting agricultural practices that favor intensive row-cropping for corn and soybeans instead of dairy farms and hayfields. Savannah Sparrows are susceptible to some crop pesticides and, owing to their foraging style, may eat granular pesticides scattered in cornfields. Savannah Sparrow nesting can be disrupted when grassy areas are mowed or fields are hayed before young have fledged. Overgrazing by expanding populations of Snow Geese in northern Manitoba may be reducing suitable habitat for Savannah Sparrows there.

Diet: During the breeding season, Savannah Sparrows eat nutritionally rich insects and spiders. They stalk through grassy areas or along beaches in search of beetles, grasshoppers, and other bugs, as well as spiders, millipedes, and pillbugs, snapping them up in their bill and swallowing them whole. When white frothy spittle masses appear on goldenrod plants, Savannah Sparrows hop up on the plant and devour the spittlebug nymphs inside the foam. On their winter range, Savannah Sparrows switch to a diet of mostly small seeds from grasses and forbs. Along coastal areas, they may eat tiny crustaceans.

Nesting: Sexes are alike. This species has a typically sparrow-like dark-streaked brown back, and whitish under parts with brown or blackish breast and flank streaking. It has whitish crown and supercilium stripes; sometimes with some yellow (more often near the beak). The cheeks are brown and the throat white. The flight feathers are blackish-brown with light brown or white border. The eyes are dark. The feet and legs are horn-colored, as is the lower part of the bill, with the upper part being dark grey.

The female builds the nest in one to three days. The nest is about 3 inches across and composed of two parts: an exterior of coarse grasses and in the middle, a finely woven tiny cup of thin grass. This inner cup is about 2 inches across and 1 inch deep. 2 to 6 eggs are laid and are pale greenish, bluish, tan, or white, with speckles and streaks. Colors vary greatly, sometimes even within clutches. Raising young is hard work: a female Savannah Sparrow must gather 10 times her weight in food to feed herself and her young during the 8 days they are in the nest.

Cool Facts: While the Savannah Sparrow’s name sounds like a nod to its fondness for grassy areas, but this species was actually named by famed nineteenth century ornithologist Alexander Wilson for a specimen collected in Savannah, Georgia.

Like many grassland sparrows, Savannah Sparrows walk along the ground to forage for bugs, occasionally running or hopping to seize prey. Flights are typically quick and low among grasses. At the outset of the breeding season, males perch on the outer limbs of shrubs and trees or atop fence posts to sing and declare their territory. They also use these vantages to keep watch over their area. If another Savannah Sparrow enters a male’s territory, he may use a “flutter flight” display to scare him away—fluttering up with his tail cocked and legs dangling, beating his wings slowly to hover in the air. Males also raise their wings vertically behind their backs in a territorial display, as well as chase intruders off their territory. Males engage in a similar type of flutter-flight display above females during courtship. In the middle and southern parts of their range, many Savannah Sparrow males breed with more than one female, though in the north of their range Savannah Sparrows tend to be monogamous (perhaps because the male’s help is needed at the nest for raising young quickly in a short northern summer). Leading up to winter migration, Savannah Sparrows gather in large flocks and become increasingly restless until one night, they depart.

There are numerous subspecies (including the Large-billed Sparrows) are currently recognized, though many are only described from wintering birds and much of the variations seem to be geographical rather than physical.

Savannah Sparrows proper

  • P. s. labradorius, Cape Bonavista, Newfoundland and Labrador. All are migratory; wintering ranges overlap widely. P. s. labradorius, breeds in Newfoundland, Labrador, and N Quebec
  • P. s. oblitus, breeds in N Ontario and Manitoba
  • P. s. savanna (Eastern Savannah Sparrow), breeds in the NE USA and adjacent Canada (includes P. s. mediogriseus)
  • P. s. sandwichensis (Aleutian Savannah Sparrow), breeds on the Aleutian Islands and W Alaskan Peninsula
  • P. s. anthinus, breeds in the remainder of Alaska, south and east to central British Columbia and north of the Great Plains to Manitoba
  • P. s. brooksi (Dwarf Savannah Sparrow), breeds in southernmost British Columbia to northernmost California
  • P. s. alaudinus, breeds in coastal northern and central California
  • P. s. nevadensis, breeds in the N Great Plains and the Great Basin
  • P. s. brunnescens, breeds from central Mexico south to Guatemala (includes P. s. rufofuscus)
  • P. s. wetmorei is a doubtful subspecies that may breed in the mountains of Guatemala. It is known from only 5 specimens, collected June 11–17, 1897, in Huehuetenango Department.

Ipswich Sparrow. Some post-breeding dispersal. Formerly considered a distinct species.

  • P. s. princeps, breeds almost exclusively on Sable Island. The Ipswich Sparrow is somewhat larger and paler in color than other eastern Savannah Sparrows. The breast streaks are narrower and pale brown and is 50% heavier than the nominate species. Some birds overwinter on the island; others migrate south along the Atlantic coast, usually departing later and returning sooner than mainland birds. Some birds interbreed with P. s. savanna in Nova Scotia. These birds frequently raise three broods in a year. This bird was first observed in winter on the dunes near the town of Ipswich, Massachusetts.

Large-billed Sparrows. The Large-billed Sparrows proper are dark, large and strong-billed subspecies.

  • P. s. rostratus, which breed on the Gulf Coast of NE Baja California and NW Sonora (some post-breeding dispersal).
  • P. s. atratus, resident on the coast of central Sonora to central Sinaloa (resident).
  • P. s. beldingi, wintering at Bolsa Chica Ecological Reserve, California (USA). The Belding's (Savannah/Large-billed) Sparrows are all-year residents of salt marshes of the Californian Pacific coast. They are dark, rufous, and have rather long but not very hefty bills.
  • P. s. anulus, resident around Sebastián Vizcaíno Bay, Baja California
  • P. s. guttatus, resident around San Ignacio Lagoon
  • P. s. magdalenae, resident around Magdalena Bay. The San Benito (Savannah/Large-billed) Sparrow is a resident bird of the Islas San Benito off Baja California; a stray bird was observed on Cedros Island on April 21, 1906.
  • P. s. sanctorum. This is a large-bodied and large-billed subspecies, similar to rostratus. They utilize different habitat and their breeding season does not seem to coincide with that of Belding's Sparrows. However, their bill size is due to convergent evolution and their habitat choice simply to the lack of alternatives on their barren island home; altogether, it appears to be a fairly recent offshoot from the Belding's Sparrows group. It appears as distinct evolutionarily from these as does the Ipswich Sparrow from the Savannah Sparrow proper group, only that there seems to have been more gene flow and/or a larger founder population in the case of the latter.

Found in Songbird Remix Sparrows of the World

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