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Status: Population size: 2 million Photo by Cornell Laboratory of Ornithology.

Botteri's Sparrow
(Aimophila botterii)

This species was on the 2002 WatchList, but is not on the 2007 WatchList. Please refer to http://web1.audubon.org/science/species/watchlist/techReport.php for information on the 2007 WatchList.

A primarily Mexican species, the range of Botteri's Sparrow just reaches the U.S. in southeastern Arizona and south Texas, and comprises two separate populations and subspecies.

Identification
Botteri's Sparrow is a drab, inconspicuous sparrow that appears somewhat flat-headed and large-billed. It is primarily dull brown and plain-breasted, with a longish, rounded tail.

Distribution and Population Trends
This species is mostly resident throughout its range. In the United States, it is only found in southeast Arizona and extreme southwest New Mexico, and the coastal region of the lower Rio Grande Valley in southern Texas. The westernmost population occupying Arizona and environs (A. b. arizonae) also extends into southern Sonora and central Chihuahua, Mexico. The Texas subspecies (A. b. texana) is found throughout much of central Mexico through the Yucatan Peninsula, and locally in Nicaragua and Costa Rica. Many, if not most, of the birds breeding in the U.S., in particular the Arizona population, probably winter in Mexico, and populations in much of Mexico are resident.

Because this species is so secretive and difficult to observe, the historical status is not entirely clear. However, by all accounts it was once much more common in Arizona (especially at the northern edge of its range), and once ranged north to Corpus Christi on the Texas Gulf Coast. It is even possible that it was extirpated in the late 1900s due to overgrazing and drought, and the U.S. was repopulated with Mexican birds. Botteri's Sparrows, like other species whose northern distribution is in the same areas, may experience natural population fluctuations along the periphery of the nesting range. Botteri's Sparrows can be locally common in suitable habitat. In 1985, the largest known breeding colony in Arizona was 350 pairs.

Ecology
Botteri's Sparrows favor tall grass habitats (with grasses at least one foot tall) with scattered bushes. The Arizona population (A. b. arizonae) nests in small colonies in semi-desert grasslands, especially in sacaton, a tall, dense bunchgrass that accumulates a great deal of standing dead material which is unsuitable for grazers. The Texas population (A. b. texana) is found in coastal prairie that is periodically flooded. Dominant plants in this habitat are Spartina grass and sea oxeye.

Botteri's Sparrows are usually on the ground, and can be difficult to see unless a male is perched on a short bush or fence singing. This species nests on the ground in May through July. Mature areas of tall grass that provide nest concealment harbor the highest densities of nesting Botteri's Sparrows.

Threats
Habitat destruction and alteration, particularly in the form of grazing, has resulted in population declines in this species. The species prefers ungrazed or lightly grazed grasslands; heavier grazing creates vegetation that is too low or weedy, and a decline in grasshoppers, which are a major prey item. Soil compaction, erosion, and conversion of grasslands to other vegetation types reduces suitable habitat. Botteri's Sparrows have the highest densities in intact sacaton habitats; this grass is itself geographically restricted and has suffered from mowing, overgrazing, trampling, altered water regimes, and farming. In Texas, habitat has been lost to development and agriculture.

Conservation
Both populations of Botteri's Sparrows appear fairly stable. In Arizona, preservation of sacaton grasslands in various stages of succession is important. This includes appropriate management of rangeland, as most remnant sacaton is on private ranches. It is recommended, for example, that ranchers not burn sacaton annually, which can kill grasses, encourage non-native species, and render habitat unsuitable for Botteri's Sparrows at least temporarily. In Texas, much of the range of the sparrow is on private or government land where extensive grazing and farming does not take place, and the habitat is protected.

Audubon's Appleton-Whittell Reseach Ranch in Arizona hosts a large population of Botteri's Sparrow and has been the center of research on the ecology and habitat requirements of the species.

What Can You Do?
Audubon's Important Bird Area program is a vital tool for the conservation of Botteri's Sparrows as well as other species. To learn more about the Important Bird Area programs in states with breeding populations of Botteri's Sparrow, and how you can help, visit: http://www.audubon.org/bird/iba/

Support local land trusts, government agencies, and other organizations working to preserve Botteri's Sparrows habitat in your area. Contact your state Important Bird Areas coordinator (http://www.audubon.org/bird/iba/state_coords.html) to find out if there are sites in your area important for Botteri's Sparrows that need increased protection.

Information on where Botteri's Sparrows occur and in what numbers is vital to conserving the species. Help in monitoring this and other species by reporting your sightings to eBird. A project of Audubon and the Cornell Lab of Ornithology, eBird is the world's first comprehensive on-line bird monitoring program: http://www.audubon.org/bird/ebird/index.html.

Volunteers are crucial to the success of programs that monitor the long-term status of wintering populations of Botteri's Sparrow and other bird species. Audubon's Christmas Bird Count (CBC) is one of the longest-running citizen-science monitoring programs in the world and has helped to follow changes in the numbers and distribution of Botteri's Sparrow. To learn more about the CBC and how you can participate, visit: http://www.audubon.org/bird/cbc.

CIPAMEX, Audubon's BirdLife International partner in Mexico, has an Important Bird Areas program that is working to protect habitat for Botteri's Sparrow and many other species. To learn more about Mexico's Important Bird Areas program and how you can help visit: http://132.248.79.80/wwwcampus/cipamex/

References
Beadle, D. and J. Rising. 2002. Sparrows of the United States and Canada: The Photographic Guide. Academic Press, San Diego, CA.

Byers, C., J. Curson, and U. Olsson. 1995. Sparrows and Buntings. Houghton Mifflin Co., New York.

Rising, J. 1996. A Guide to the Identification and Natural History of the Sparrows of the United States and Canada. Academic Press, San Diego, CA.

Webb, E. A. and C. E. Bock. 1996. Botteri's Sparrow (Aimophila botteri). In The Birds of North America, No. 216 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists' Union, Washington, D.C.