Bird of the Month: Vesper Sparrow
Written by Andy McCormick
Andy McCormick, Volunteer and Former Board President of Eastside Audubon
The Vesper Sparrow is a grassland specialist which often sings in the evening.
Vesper Sparrow
Scientific Name: Pooecetes gramineus
Length: 6.25””
Wingspan: 10”
Weight: 0.91 oz (26 g)
AOU Alpha Code: VESP
A CRYPTICALLY PLUMAGED SPARROW
The Vesper Sparrow is a large, pale, dishwater gray-brown, ground-loving, streaky sparrow. Many birders might say this sounds like many of the sparrows we know, but upon a closer look the Vesper Sparrow provides an opportunity to focus on some finer details of birds that are useful in identifying many sparrows. The Vesper has several distinctive pale markings on the face, which aid identification and remind us to look carefully at these details.
“The uniformity of the [cryptic] pattern, however, makes the pale markings about the face really stand out. These marks include pale lores, a pale eye-line, a pale mustache, and (especially) pale cheeks….whereas, the facial pattern of other sparrows is defined by dark markings on a pale surface, this one is more readily distinguished by a pale rendering on a bland surface. Also, surprisingly evident is a narrow white eye-ring” (Dunne, p. 599).
A SPARROW OF WEEDY GRASSLANDS
The Vesper Sparrow forages almost exclusively on the ground in open areas of grasslands and weeds among short shrubs and patchy grass. It seeks beetles, grasshoppers, caterpillars, moths, and some spiders. In winter it relies on finding the seeds of many weeds. Generally speaking, it prefers habitat that has some shrubs, even very short ones of only a few inches, which the male uses as a perch for singing to mark territory.
The Vesper Sparrow is the only species in the genus Pooecetes, from the Greek for grass dwelling; poe, grass, and oiketes, dweller. The species epithet is gramineus, from the Latin for covered with grass. Vesper refers to the evening when this bird can be heard singing. Vespers is also the name of the canonical hour for evening prayer. Sparrow is from the Anglo-Saxon, spearwa, meaning to flutter (Holloway). Photos and recordings of the Vesper Sparrow can be found at the Macaulay Library.
GROUND NESTER
The Vesper Sparrow nests on the ground in a slight depression near a grass clump, weed, or shrub (Kaufman). The nest is a bulky open cup lined with fine grasses into which 3-4 eggs are deposited and incubated by the female. If the nest is threatened, the female will fly away as if to distract the intruder and lure it away from the nest. Characteristically, the Vesper Sparrow will fly away when disturbed. This behavior offers an advantage for the birder who can then see the white outer tail feathers as the bird flies away. Because when the tail of a bird is folded, the outer tail feathers end up on the bottom, the tail of the Vesper Sparrow looks all white from below.
STATUS AND DISTRIBUTION
The distribution of Vesper Sparrow has responded to the availability of grassland, which has varied over the past two centuries both in the State of Washington and across the continent of North American. As settlers to North America cut down forests for farmland in the 19th Century, the Vesper Sparrow was abundant in the east. However, during the second half of the 20th Century forests have expanded as farms were abandoned and the Vesper Sparrow’s habitat has contracted (Wahl, Tweit, & Mlodinow, Jones & Cornely).
In Washington, the population of Vesper Sparrow has expanded east of the Cascades especially at higher elevations where native grasses predominate. Ironically, the loss of sagebrush habitat has aided Vesper Sparrow, which will replace Brewer’s and Sagebrush Sparrows as sagebrush is removed.
However, Vesper Sparrow is in danger of extirpation in Western Washington. A remnant population continues in the remaining area of the South Sound Prairies, following decades of suitable habitat being destroyed by development, invasion of scotch broom, and expansion of forests resulting from fire control (Wahl, Tweit, & Mlodinow).
Photo by Tom Murray. References available upon request from amccormick@eastsideaudubon.org.