Vesper Sparrow
Pooecetes gramineus

Migratory Status: Short-distance migrant

PIF Population Estimate: 30 000 000

Percent of western hemisphere population breeding in boreal forest: <25%

PIF Maximum Detection Distance (m) : 200

Canadian BBS Population trend: -0.3 n.s. (-1.0 to 0.4)

Life History

The Vesper Sparrow is a large, non-descript and heavily streaked sparrow found in open grasslands. It has an overall brownish-gray appearance with white outer tail-feathers and a conspicuous white eye-ring. The underparts are whitish with a necklace of dark streaks on the breast, while the upperparts are noticeably darker. The Vesper Sparrow breeds over a wide area of southern Canada and the northern half of the United States. It is primarily a sub-boreal species, but does occur as far north as the southern Mackenzie valley. In winter, this species occurs in most of the southern United States and south to central Mexico.

Grasslands and arid steppes are the favoured habitats of the Vesper Sparrow in all seasons. They prefer dry sites with patches of open ground and the occasional tall shrub or fence post as a perch. The Vesper Sparrow tends to avoid croplands, but readily breeds along weedy roadsides and fencelines. Vesper Sparrows are territorial, but commonly coexist with other grassland sparrow species. Aggressive interactions with neighbouring Vesper Sparrows are rare. Territories are variable in size and range from 0.3 to 8.2 ha, seemingly depending on food availability.

Vesper Sparrows forage on the ground, glean insects from low vegetation, or hover to snatch insects from taller shrubs. Grass and weed seeds are consumed year-round, but during the breeding season, large quantities of beetles, caterpillars, spiders and other arthropods are eaten. The song is cheery, loud and has multiple syllables. The song starts with two to four long, clear notes, followed by a variable number of slurred trills that weaken towards the end. The sweet-sounding song is familiar to rural residents and it is often haphazardly dubbed onto motion picture sound tracks as the ubiquitous background bird song, regardless of scenery or habitat.

Males sing from elevated locations, but not necessarily the highest perch. Vesper Sparrows sing all day in the breeding season, with most vocal activity in the morning. A second chorus of song occurs in the failing evening light; occasional songs may continue after sunset. Vesper Sparrows may also give extended flight songs. The song is repeated while the male rises up to 75 m above the ground, then flies horizontal for another 100 to 200 m in before descending.

Reference(s)

Jones, S. L., and J. E. Cornely. 2002. Vesper Sparrow (Pooecetes gramineus), The Birds of North America Online, . A. Poole, Ed. Ithaca: Cornell Laboratory of Ornithology; Retrieved from The Birds of North America Online database: http://bna.birds.cornell.edu/bna/species/624