Dickinson Ch10: Northern Bobwhite

I. Taxonomy, Description, and Distribution

Taxonomy: The northern bobwhite is the only living representative of the genus Colinus in North America, belonging to the family Odontophoridae.
- Scientific name: Colinus virginianus.
Morphology: Bobwhites are compact galliform birds with short, rounded wings and well-developed breast muscles. They are rapid flyers for short distances, reaching 28–38 miles/hr.
- Males have a distinctive white throat and stripe, contrasting with the buff markings on females.
Range and Habitat: They have a broad distribution, found in diverse ecosystems ranging from pine/grassland in the southeast to agricultural lands in the Midwest.
- Bobwhites are typically early successional generalists, frequently following human-caused disturbances like fire or agriculture.
Population Status: Historically, bobwhites provided important recreational, social, and economic values. However, in recent decades, bobwhite populations and hunting have declined throughout the range, primarily attributed to land use changes associated with modern agricultural and silvicultural practices.
- From 1966-1996, bobwhite populations in the Southeast declined at a rate of 3.9%/year.

II. Habitat Requirements and Management

Essential Components: Bobwhite habitat requires three components: 1) adequate escape/roosting/loafing cover (usually dense, shrubby vegetation), 2) suitable nesting/brood cover, and 3) grassland or annual weed communities for food.
Management Goal: The goal is to provide an area usable for bobwhite "at all times".
Disturbance Dependence: Bobwhites are disturbance-dependent, adapted to early successional habitats. Disturbance regimes (fire, rotational agriculture, disking) are necessary to maintain populations.
- Prescribed Fire: Fire is integral to creating and maintaining southeastern ecosystems. In forested systems, prescribed fire is essential and should be applied annually or on a 2-3 year rotation to control hardwood encroachment and maintain herbaceous ground cover.
- Disking: Prescribed fire and fall disking stimulate germination of weeds important to quail (e.g., partridge pea). Strip disking on a 2-3 year rotation creates a mosaic of annual and perennial communities.
Supplemental Food: While supplemental foods (grains, seeds, legumes like cowpea, sorghum, partridge pea) can be managed, providing adequate winter food resources is complicated. The primary objective of habitat management should be to supply reliable year-round food and cover through habitat manipulation.

III. Feeding Habits

Bobwhites are opportunistic foragers.
Adult Diet (Fall/Winter): Primarily seeds, weeds, and cultivated grains. Important foods include corn, lespedeza, acorns, and soybeans.
Chicks/Spring/Summer: Chicks require a high protein diet (>28%) during the first 10 days. Insects are the primary food source for newly hatched chicks, essential for protein. In Mississippi, the diet of chicks included true bugs, grasshoppers, caterpillars, and ants.
Breeding Female Diet: Invertebrates are an important source of protein for producing active females.

IV. Reproduction and Survival

Breeding Season: The primary breeding season generally extends from mid-June through September, but bobwhites may continue nesting into October if conditions allow.
Reproductive Effort: Bobwhites exhibit a high potential for productivity through repeated renesting and double-clutching. If the first nest is destroyed, females usually lay a second clutch.
- Double-clutching (when females successfully rear two broods in a season) occurs, but typically represents a relatively small fraction (0–7%) of total production.
Mortality Factors:
- Predation: Predation is the primary cause of mortality in many studies. Avian predators (e.g., Cooper's hawks, sharp-shinned hawks) account for 60–65% of total mortalities in parts of North Carolina and Florida. Mammalian predators (e.g., skunks, foxes, raccoons) are significant predators of nests.
- Disease/Parasites: Over 30 diseases have been reported. Histomoniasis (blackhead), a protozoan parasite, is widespread and a significant disease factor, particularly in pen-reared birds. Avian pox is a viral infection that can cause substantial annual mortality.
Harvest: Harvesting below optimal, sustainable limits generally has little observable effect on bobwhite survival and breeding density, operating under the principle of "harvestable surplus".

Analogy for Bobwhite Habitat Management:

Managing Northern Bobwhite habitat is like tending a perpetual garden that requires regular, carefully controlled weeding. The bobwhite is the specific plant you want to grow, but it only thrives in "weedy" patches (early successional habitat). If you neglect the garden (i.e., stop disturbance), the "weeds" are quickly replaced by large, aggressive "trees" (mature forest/dense growth), shading out the bobwhite's preferred small, quick-growing plants (food and cover). Therefore, tools like fire and disking act as your pruning shears and hoe, constantly restarting the cycle to keep the garden in that optimal, messy, early-stage growth where the bobwhite flourishes.