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Colinus virginianusnorthern bobwhite

By Matthew Chumchal

Geographic Range

Northern bobwhites can be found from southeastern Ontario to Central America. Highest population densities are reached in the eastern United States and Mexico. Bobwhites can also be found throughout Cuba. Disjunct populations exist in Washington, Oregon, Idaho and northwestern Mexico. (Dimmick, 1992)

Habitat

In forest habitats, northern bobwhites show a clear preference for early successional vegetation created by disturbances from fire, agriculture, and timber-harvesting. In rangeland habitats, bobwhites are found in both early and later successional vegetation. Bobwhite habitats must contain a diversity of invertebrates, seeds, and herbaceous plants. Cover that provides protection from predators, weather, and provides nesting material is also essential. Water is not normally an important factor in habitat determination of the bobwhite because ample water can be obtained from dew. (Brennan, 1999; Dimmick, 1992)

Physical Description

Bobwhites are small (140 to 170 grams) galliform birds with rounded wings and a square tail. They range in length from 20.3 to 24.7 cm with a wingspan from 9 to 12 cm. Bobwhites are sexually dimorphic with regard to facial and throat coloration, wing coverts, and beak color. Adult males are distinguished by white facial stripes and throat in contrast to the buff coloration of females and juveniles. The wing coverts of males have sharply contrasting black markings on the feathers while the wing coverts of females lack color distinctions. The base of the mandible is black in males and yellow in females. White edges, dark bars, and vermiculations on the reddish brown back and white breast create a mottled appearance. (Dimmick, 1992)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • male more colorful
  • Range mass
    140 to 170 g
    4.93 to 5.99 oz
  • Range length
    20.3 to 24.7 cm
    7.99 to 9.72 in
  • Range wingspan
    9 to 12 cm
    3.54 to 4.72 in

Reproduction

Originally thought to be monogamous, there is now clear evidence of ambisexual polygamy among northern bobwhites, meaning that both males and females are known to incubate and raise broods with more than one mate during the breeding season. (Brennan, 1999)

Courtship and pair formation can begin as early as February in south Texas while occurring later at higher latitudes. Nest building, egg laying, and incubation occur intensively from May to August. The beginning of the nesting season in Texas has been tied to rainfall and vegetation growth. Bobwhites mate in their first year of life and rear one brood a year. Nests destroyed before hatching will be rebuilt while broods lost after hatching are usually not replaced. South Texas broods have been reported as late as November and December.

Breeding pairs build ground nests of dead grasses. Dimmick (1992) reports the frequent use of broomsedge (-Andropogon virginicus-) in nests. Nests are saucer shaped softball size depressions in the ground (Klimstra and Roseberry 1975, Dimmick 1992). Klimstra and Roseberry (1975) found 85% of nests to be domed or covered with a canopy. Nest with no canopies were found to be significantly more common later in the breeding season (Klimstra and Roseberry 1975). Dimmick (1992) reports nest construction can occur over two days and take approximately 4 hours. Data are conflicting as to which sex actually builds nests. Klimstra and Roseberry (1975) and Stokes (1967) observed pairs building nest while other studies have found that males completed the majority of nest building (Dimmick 1992). Eggs are laid at a rate of one per day beginning one day after the nest is completed (Dimmick 1992). Multiple hens have been shown to lay eggs into a single nest with average clutch sizes of 12 to 14 eggs (Dimmick 1992). Klimstra and Roseberry (1975) report variation in single female clutch sizes of 6 to 28 eggs. Bobwhites reduce clutch size after each nest failure (Dimmick 1992). The incubation period is approximately 23 days (Dimmick 1992). Klimstra and Roseberry (1975) reported incubation by males at 26.4% of nests observed. Stokes (1967) observed exclusive incubation by both males and females. Females have been observed laying a second clutch and incubating them while the male tends to the original nest. Both parents alternate brooding of the young. Both parents have been observed to defend young by attacking perceived aggressors and by performing broken wing displays. (Brennan, 1999; Dimmick, 1992; Klimstra and Roseberry, 1975; Stokes, 1967)

  • Breeding interval
    Northern bobwhites typically breed once yearly, although there can be up to three broods per breeding season.
  • Breeding season
    Breeding occurs from February to October, depending on the region.
  • Range eggs per season
    6 to 28
  • Average eggs per season
    12-14
  • Average eggs per season
    15
    AnAge
  • Average time to hatching
    23 days
  • Average time to hatching
    23 days
    AnAge
  • Average fledging age
    14 days
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Bobwhite hatchlings are able to walk about and follow their parents almost immediately following hatching. Both males and females incubate the eggs, brood the hatchlings, and provide for the young until they reach independence at about 2 weeks old. Both parents have been observed to defend young by attacking perceived aggressors and by performing broken wing displays. (Brennan, 1999)

  • Parental Investment
  • no parental involvement
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

Lifespan/Longevity

Northern bobwhites have a short life span and high mortality rates. Few individuals live longer than five years, and about 80% live less than one year. Exposure is an important source of mortality during the winter. Deep snows and prolonged periods of cold may cause extensive losses. Also, feeding in agricultural environments can lead to exposure to contaminants which often have lethal effects. (Brennan, 1999)

  • Range lifespan
    Status: wild
    6 (high) years
  • Typical lifespan
    Status: wild
    8 to 12 months

Behavior

Beginning in late summer bobwhites form coveys of parents, offspring, and unsuccessful breeding pairs. Coveys are fluid and by autumn family groups have become dispersed due to apparently random joining and leaving of individuals (Dimmick 1992).

Bobwhites have many calls initiating and directing group movement; 1 call for food location, 11 to aid in the avoidance of enemies, 6 sexual and agonistic and 2 parental calls. Bobwhites have a male social hierarchy system (Stokes 1967).

Bobwhites are typically diurnal. Feeding is most active during the early morning and late afternoon. They can fly relatively short distances, with the average flight lasting 5.1 seconds, but spend most of their time on the ground. (Brennan, 1999; Dimmick, 1992; Stokes, 1967)

Populations are typically sedentary, year-round residents, particularly in areas of moderate to high quality habitat. Population density depends upon many factors, such as frequency and intensity of disturbance. Densities of 2.2 to 4.4 birds/hectare are typical in high quality habitat, and densities can reach up to 6.6 birds/hectare.

  • Range territory size
    .1 to .6 km^2

Home Range

Home range sizes are highly variable depending on habitat conditions and reproductive status of individuals. Unmated males roam over larger areas than mated males. (Brennan, 1999)

Communication and Perception

The well known "bob-white" call is a minor part of northern bowhites' overall vocal repetoire. Their entire vocal array is known and has been classified into calls based on group movement, food-finding, avoidance of enemies, and reproduction (sexual and parental). Nonvocal interactions are diverse and characteristic of many small quails. For example, head-shaking, head-scratching and preening are characteristic of dominant birds. (Brennan, 1999)

Food Habits

The diet consists primarily of seeds but also includes green leafy material, fruits, and invertebrates. Approximately 85% of the diet is vegetation and 15% animal matter. However, the relative quantity of each is seasonal (Ehrlich, et al 1988).

In early spring, leafy material is an important source of vitamins. Insects are important from spring until autumn; during these months they may constitue a quarter of the diet. Females consume more insects than males in response to elevated need for protein during egg laying. Fruits are also an important summer source of carbohydrates. Seeds and legumes constitute the majority of the bobwhite diet in fall and winter. Hatchlings are completely dependent on insects as a food source (Landers and Mueller 1986).

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit
  • flowers

Predation

Predation is an important source of mortality for northern bobwhites. Known predators include Cooper's hawks, raccoons, opossums, skunks and foxes. When adults with chicks encounter predators, they perform distraction displays such as fluttering and wing-dragging. This anti-predator behavior seems to be learned and is rarely seen in captive-reared birds. Their coloration helps to make them hard to see in the dense undergrowth that is their preferred habitat. (Brennan, 1999)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Northern bobwhites are host to parastic worms. These worms do not often kill their host, but their presence is associated with low body weight in northern bobwhites and this may negatively influence survival and reproduction. Northern bobwhites also host a wide variety of external parasites such as lice, ticks, mites, and fleas. (Brennan, 1999; Brennan, 1999)

Northern bobwhites are important prey for birds of prey and small, terrestrial predators. They are also important seed and foliage predators and may influence the plant communities in which they live.

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Economically, northern bobwhites are one of North America's most important game birds, especially in the southern and midwestern United States. Annual harvest in 1970 was estimated to be 35 million birds in 37 states and 2 Canadian provinces, the largest harvest of non-migratory upland game birds (Dimmick 1992). Northern bobwhites are one of the most extensively studied species of birds in the world. They have played a major role in captive laboratory studies to test the physiological and behavioral effects of pesticides on wildlife. They also were the subject of the first modern systematic study of a wild animal's life history in relation to environmental and habitat factors that influence its abundance. (Brennan, 1999; Dimmick, 1992)

  • Positive Impacts
  • food
  • research and education

Economic Importance for Humans: Negative

There are no known adverse affects of northern bobwhites on humans.

Conservation Status

Populations of northern bobwhite are declining. Habitat loss, particularly due to the increase in large-scale farming and the reduction of fence rows and suitable habitat plots are thought to be the major factor in the decline. One subspecies, the masked bobwhite (Colinus virginianus ridgwayi), is considered endangered. Northern bobwhite are listed as near threatened by the IUCN. (Brennan, 1991)

Contributors

Kathleen Bachynski (editor), University of Michigan-Ann Arbor, Tanya Dewey (editor), Animal Diversity Web.

Kari Kirschbaum (editor), Animal Diversity Web.

Matthew Chumchal (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

"Northern Bobwhite" (On-line). Discover Life in America. Accessed March 17, 2004 at http://www.dlia.org/atbi/species/animals/vertebrates/birds/odontophoridae/northern_bobwhite.html.

Brennan, L. 1991. How can we reverse the northern bobwhite quail population decline?. Wildlife Society Bulletin, 19: 544-555.

Brennan, L. 1999. Northern Bobwhite. The Birds of North America, No. 397: 1-28.

Dimmick, R. 1992. Northern bobwhite (-Colinus virginianus-): Sec 4.1.3. U.S. Army Corps of Engineers wildlife resources manual, .

Klimstra, W., J. Roseberry. 1975. Nesting ecology of the bobwhite in southern Illinois. Wildlife Monographs, : 1-37.

Landers, J., B. Mueller. 1986. Bobwhite quail management: a habitat approach. Tall Timbers Research Station Miscellaneous Publication, : 1-39.

Stokes, A. 1967. Behavior of the Bobwite, -Colinus virginianus-. The Auk, : 1-33.

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