Aimophila aestivalis

Geographic Range

Bachman's sparrows are found in the southeastern United States. Most of the populations live in Florida and along the Gulf Coast. They are also found as far north as the Indiana-Michigan border and as far west as the Arkansas-Oklahoma border. In the winter, Bachman's sparrows are especially secretive and little is known of their winter habits. Their winter range seems to be compressed into the coastal southeastern U.S., Florida, the Gulf states, and eastern Texas.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Bachman's sparrows are mostly found in open oak and pine forests with abundant grasses. They are most often found in forests with wiregrass ( Aristida ) or broomsedge ( Andropogon ). Populations are highest in areas where forest fires are regular, eliminating hardwood understory shrubs. Bachman's sparrow populations disappear 4 to 5 years after a burn. Much of their original habitat, open pine forests, has been logged throughout their range, forcing them into marginal habitats, such as forest edges and utility rights-of-way, where hardwood understory shrubs are discouraged by poor soils, fires, or human management.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• scrub forest scrub forest

Physical Description

Bachman's sparrows are relatively small in size and plain brown in color with reddish streaks. They have cone shaped bills and pale brown faces. Bachman's sparrows have long brown tails with reddish brown backs. The breast is pale white in color. Bachman's sparrows also have a brownish-red crown. They are 12.2 to 15.2 cm long and about 21 grams in weight. They may be confused with a related species, Aimophila botterii in southeastern Texas, where their ranges overlap. However A. botterii is found in grasslands. They may also be confused with field sparrows ( Spizella pusilla ), which have smaller bills and tails, a white eye ring, less color on the face, and two white wing bars.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

Bachman's sparrow males begin singing to attract mates and defend mating territories in late February to early March. Mating behaviors are poorly documented. These sparrows seem to be primarily monogamous and males may follow females closely to guard them from other males.

• Mating System
• monogamous monogamous

After Bachman's sparrows have paired, females build a cup-shaped nest of grasses and other vegetation and lined with fine grass and fur on the ground, usually under overhanging vegetation or in a clump of grass. They lay two sets of eggs each mating season, the first usually in May and June, the second later in the season. Females incubate the eggs, from 2 to 5 in each brood. Males tend to females when they are off the nest. The eggs hatch in 12 to 14 days and the young depart from the nest 9 to 10 days after hatching and can fly soon after. They are at full adult size by 25 days post-hatching.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

Young are altricial at hatching. Females brood the young and males provide food to the female while brooding. Males pass food to females who then pass it to the nestlings. After the brooding period, both males and females protect and provide food for the nestlings. Young are fed insects and parents remove their fecal sacs.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • male
    • female
  • protecting
    • male
    • female

Lifespan/Longevity

There is little available information on longevity in Bachmann's sparrows. Studies have shown survival into their third and fourth years.

Behavior

Bachman's sparrows have been observed hiding in the burrows of other animals. The suspected reason for this is for protection from predators. Bachman's sparrows are active during the day. Northern populations seem to be migratory, migrating to warmer areas in the coastal southeastern U.S.. Southern populations seem to be resident. Little is known about the migration of these birds. Bachman's sparrows are active during the day, during the breeding season they forage mostly during the first 5 hours of the day and 2 hours before sunset. Bachman's sparrows are mainly active on the ground. When disturbed they often drop from flight and run on the ground to escape. Their flight is described as weak and "floppy" as their tail pumps during flight.

• Key Behaviors
• arboreal arboreal
• terricolous
• flies
• diurnal diurnal
• motile motile
• migratory migratory
• sedentary sedentary
• territorial territorial

Home Range

Breeding territories range in size from 0.62 to 5.1 hectares.

Communication and Perception

Bachman's sparrows use songs and calls to communicate with conspecifics. Vocalizations are sometimes the most reliable way of distinguishing among sparrow species. Bachman's sparrows have 3 main songs, used by mails to attract females for breeding: primary songs, whisper songs, and excited songs. The primary song is described as one of the most beautiful sparrows songs. Both males and females use "calls", which include "chip", "pseet", "chitters", used in mate recognition and aggression, and others.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Bachman's sparrows are omnivorous, eating mainly insects and seeds. The feed on the ground. Insects consumed include beetles, bugs, grasshoppers, crickets, millipedes, and spiders. They also eat the seeds of grasses, especially Panicum species, sedges, and wood sorrel.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
• herbivore herbivore
  • granivore granivore
• omnivore omnivore

• Animal Foods
• insects
• terrestrial non-insect arthropods

• Plant Foods
• seeds, grains, and nuts

Predation

Predation on adult Bachman's sparrows is not documented. Known predators of Bachman's sparrow nestlings and eggs include crows and snakes, especially Coluber species and Elaphe species. In one study 12% of all Bachman's sparrows eggs were eaten by snakes. Brown-headed cowbird nestlings will often directly or indirectly kill Bachman's sparrow nestlings when they parasitize their nests. Adult Bachman's sparrows will feign an injury to distract predators near their nests.

Ecosystem Roles

There is little known about the role of Bachman's sparrows in the ecosystem. One can speculate that they aid in seed dispersal through seed eating and that they help to control insect populations. They are parasitized by brown-headed cowbirds ( Molothrus ater ) who lay their eggs in Bachman's sparrow nests. Bachman's sparrows seem to rely on similar habitats to those required by red-cockaded woodpeckers ( Picoides borealis ).

Several ectoparasites are known from Bachman's sparrows: Analgopsis mites, the tick Haemaphysalis leporis-palustris , and lice in the genus Ricinus . Blowfly larvae ( Protocalliphora deceptor ) are known from nests.

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

Bachman's sparrows have no direct effect on humans. One could argue that they play a key role in the food chain, in that they eat insects and other arthropods and keep their population down.

Economic Importance for Humans: Negative

Bachman's sparrows are not harmful to humans.

Conservation Status

The main threat to Bachman's sparrows is the elimination of the open pine forest habitat on which they rely. Since they nest on the ground, they are especially vulnerable. On the IUCN Red List they are listed as low risk. But they are protected under the Migratory Bird Act. They are given no special status on the US Federal List and CITES. In Tennessee Bachman's sparrows are listed as endangered, they are threatened in North Carolina, Oklahoma, and Kentucky. Bachman's sparrows are relatively rare, because of this there is not a lot known about this species. Bachman's sparrows rely on similar habitats to those required by red-cockaded woodpeckers ( Picoides borealis ). The protection of open pine forests throughout the southeastern United States has impacted populations of both rare bird species.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (author, editor), Animal Diversity Web, Nick Darin (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

References

Dean, T., P. Vickery. 2003. Bachman's Sparrows use burrows and palmetto clumps as escape refugia from predators. BIOONE , 74/1: 26-30. Accessed October 15, 2006 at http://www.bioone.org/perlserv/?request=get-document&issn=0273-8570&volume=074&issue=01&page=0026 .

Dunning, J. 1993. The Birds of North America . Philadelphia, PA: The American Ornithologists' Union and The Academy of Natural Sciences of Philadelphia.

Haggerty, T. 1992. Effects of Nestling Age and Brood Size on Nestling Care in the Bachman's Sparrow ( Aimophila aestivalis). JSTOR , 128: 115-125. Accessed October 07, 2006 at http://www.jstor.org/view/00030031/di003540/00p0254t/0 .

Max Planck Institute, 2002. "Longevity Records" (On-line). Accessed October 11, 2006 at http://www.demogr.mpg.de/longevityrecords/0303.htm .

Meyer, R. 2006. "Aimophila aestivalis. In: Fire Effects Information System" (On-line). Accessed October 07, 2006 at http://www.fs.fed.us/database/feis/ .

Missouri Dept. of Conservation, 2009. "Endangered Species Guidesheet" (On-line). Accessed October 07, 2006 at http://mdc.mo.gov/nathis/endangered/endanger/bachspar/index.htm .

The Georgia Museum of Natural History, , Georgia Department of Natural Resources. 2006. "Sparrows" (On-line). Accessed October 07, 2006 at http://museum.nhm.uga.edu/gawildlife/birds/passeriformes/aaestivalis.html .

USGS, 2010. "Bachman's sparrow Aimophila aestivalis" (On-line). Accessed October 07, 2006 at http://www.mbr-pwrc.usgs.gov/id/framlst/i5750id.html .

US Army Corps of Engineers. Species Profile: Bachman's Sparrow (Aimophila aestivalis) on Military Installations in the Southeastern United States. SERDP-98-11. Vicksburg, MS: SERDP. 1998. Accessed October 07, 2006 at http://el.erdc.usace.army.mil/tes/pdfs/serdp98-11.pdf#search=%22Wilma%20A%20mitchell%20bachman's%20sparrow%22 .