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Brewer's Sparrow

Spizella breweri ORDER: PASSERIFORMES FAMILY: EMBERIZIDAE

IUCN Conservation Status: Least Concern

Brewer’s Sparrows are at first glance so subtly marked that they’ve been called the “bird without a field mark.” These streaky, gray-brown sparrows are notable for their reliance on sagebrush breeding habitat, and their plumage is elegantly tuned to their muted, gray-green home. They’re the most abundant bird across the vast sagebrush steppe, and their long, trilling songs are a signature sound of the landscape. A markedly different subspecies lives among the stunted trees and shrubs at timberline in Canadian mountains.

At a GlanceHelp

Measurements
Both Sexes
Length
5.1–5.9 in
13–15 cm
Wingspan
7.1–7.9 in
18–20 cm
Weight
0.4–0.5 oz
11–14 g
Relative Size
About the size of a Black-capped Chickadee; noticeably smaller and slimmer than a Song Sparrow.

Cool Facts

  • Adapted to arid environments year-round (sagebrush in summer; desert grasslands in winter), Brewer’s Sparrows can go weeks without drinking.
  • In spring and early summer, male Brewer’s Sparrows sing a long, rich, trilling song that can last 15 seconds. Roger Tory Peterson wrote that they sound like “a Chipping Sparrow trying to sing like a canary.” Once the males pair up with their mates for the season, they switch to a much shorter, 3-second song consisting of two trills.
  • Brewer’s Sparrows are so unremarkable looking that they’re remarkable. In 1923, the naturalist William Dawson wrote that Nature had “done her utmost to produce a bird of non-committal appearance… Mere brown might have been conspicuous by default, but brownish, broken up by hazy streakings of other brownish or dusky… has given us a bird which… may be said to have no mark of distinction whatever—just bird.” Later researchers noted that they preferred to describe the bird as “subtle.”
  • While large wintering flocks usually communicate with soft call notes, a rare occasion might inspire a male to sing his “long song.” This spurs on other members of the flock, and soon, there’s a veritable chorus.
  • Brewer’s Sparrows’ lives are intimately tied to the sagebrush: it’s where they eat, sleep and nest. But there’s an exception: the “Timberline” form lives in an entirely different habitat at high elevations in Canadian mountains, where there’s little or no sage.
  • The oldest known Brewer’s Sparrow was at least 5 years, 2 months old when it was recaptured and rereleased at a banding site in Colorado.

Habitat


Scrub

Brewer’s Sparrow is one of only a handful of “sagebrush obligate” bird species (including Sage Thrasher, Sagebrush Sparrow, and the two species of sage-grouse: Greater and Gunnison). Brewer’s Sparrows depend almost exclusively on the sagebrush ecosystem when breeding. This mostly treeless habitat covers an immense area of the arid West, and is found nowhere else. It tends to be dominated by big sagebrush (Artemisia tridentata) and similar species that grow up to about 5 feet tall, interspersed with bunchgrasses and bare ground. Some Brewer’s Sparrows also use large clearings in pinyon-juniper woodlands, which share similar vegetation with the traditional sagebrush steppe. The northern subspecies (aptly called “Timberline Sparrow”) breeds at high elevations, where dense and tall vegetation gives way to the dwarf willow and birch shrubs of alpine valleys. During winter, Brewer’s Sparrows (of both subspecies) occupy sagebrush shrublands similar to the breeding grounds, as well as a range of desert scrub habitats consisting mainly of saltbush and creosote.

Food


Insects

Brewer’s Sparrows eat mostly small insects during the breeding season, including caterpillars, leaf beetles, weevils, grasshoppers, ants, and other insects and spiders. Less is known about what they eat on their wintering grounds, but they probably eat a greater proportion of seeds. They glean insects from bark and foliage of shrubs and they pick up seeds from the ground. During the breeding season, adults spend up to three-quarters of their foraging time in shrubs, as opposed to on bare ground or at the base of bunchgrasses between shrubs.

Nesting

Nesting Facts
Clutch Size
2–5 eggs
Number of Broods
1-2 broods
Egg Length
0.6–0.7 in
1.6–1.7 cm
Egg Width
0.5–0.5 in
1.2–1.3 cm
Incubation Period
10–12 days
Nestling Period
6–9 days
Egg Description
Blue-green, spotted with dark brown or reddish brown.
Condition at Hatching
Naked except for sparse tufts of light gray natal down.
Nest Description

Females do most of the nest-building, taking 4 to 5 days to build their first nest of the season and as little as 2 days for subsequent nests. The nest is a small cup of dry grasses, with the outermost layer sometimes composed of sagebrush twigs. The cup interior made of fine grasses, sagebrush bark, and sometimes hair. Nests measure roughly 3.5 inches across, and the cup diameter is about 2 inches.

Nest Placement

Shrub

Brewer’s Sparrows choose tall and densely branching shrubs (most often big sagebrush, Artemisia tridentata) for nesting. They place their nests just outside the shrub’s densest parts. Compared to the landscape as a whole, the immediate area surrounding nests tends to have more sagebrush cover and less bare ground and grass cover. They build their nests safely below the top of the sagebrush shrub but only rarely nest lower than 8 inches off the ground.

Behavior


Foliage Gleaner

Males arrive on breeding grounds several days before females, and sing from prominent perches to establish and defend breeding territories. Pairs appear to be monogamous but, as with many birds, they may mate with neighbors covertly. Perhaps to minimize this chance, males accompany their mates and aggressively chase away interlopers prior to egg-laying). Males sometimes offer food to their mates during early pair formation. Females soliciting this courtship feeding droop and quiver their wings, and sometimes utter a soft twittering call. After nests are built, males remain in the immediate vicinity, alternating between foraging within shrubs and singing atop them. Larger Sagebrush Sparrows and Sage Thrashers with overlapping territories will displace Brewer’s Sparrows from singing perches; however, Brewer’s Sparrows will also join these species to mob and chase small mammalian nest predators. Both parents handle the work of incubation and caring for young, though the female does more of the work. In winter, Brewer’s Sparrows form mixed-species flocks with other sparrows, particularly others in the Spizella genus. Predators include gopher snakes, rattlesnakes, chipmunks, long-tailed weasels, Common Ravens, Black-billed Magpies, Loggerhead Shrikes, and American Kestrels.

Conservation

status via IUCN

Least Concern

The Brewer’s Sparrow remains the most abundant bird of the sagebrush ecosystem, however, populations declined by about 49% between 1966 and 2014, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 13 million with 99% spending some part of the year in the U.S., 1% breeding in Canada, and 60% wintering in Mexico. They rate a 12 out of 20 on the Conservation Concern Score. They are a U.S.–Canada Concern Species; they are not on the 2014 State of the Birds Watch List. As with other sage-dependent birds, concerns include habitat degradation and fragmentation throughout the intermountain West of North America. In the sagebrush ecosystem, threats include livestock grazing, residential and energy development, agricultural conversion, and invasive species such as cheatgrass, which alters the natural fire regime.

Credits

Range Map Help

Brewer
View dynamic map of eBird sightings

Migration

Short-distance migrant. Brewer’s Sparrows move from breeding grounds in the sagebrush to wintering grounds in the Desert Southwest and Mexico.

Find This Bird

Brewer’s Sparrows are habitat specialists, so the first step in finding them is to find their habitat. In spring or early summer, head out into the sagebrush early in the morning and listen for a male to sing his long, trilled song. You may also spot a small, gray-brown bird unobtrusively foraging within or on the ground below a clump of sagebrush. In winter, visit desert grasslands, where there are sometimes large flocks of several species of sparrows, including Brewer’s.

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