Northern bobwhite (Colinus virginianus) COSEWIC status report: chapter 2

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COSEWIC Executive Summary

Species Information

The Northern Bobwhite, Colinus virginianus, (French name: Colin de Virginie) is a member of the New World quail family Odonotophoridae. It is a small, grouse-like bird; males have a black necklace, white throat and a white line above the eye, females have a buffy throat and eye-stripe. 

Distribution

The Northern Bobwhite is found from southeastern Wyoming east to Massachusetts south through eastern Mexico to western Guatemala. In Canada it is found only in southern Ontario, with natural populations likely restricted to Walpole Island and perhaps the adjacent mainland.  It has been introduced to many other areas with limited long-term success.

Habitat

The Northern Bobwhite requires an early successional habitat that can be provided in a variety of vegetation types. Minimally it requires an interspersion of grassland, cropland, and brushy cover. In Ontario it is now usually associated with cultivated lands rather than native prairie fringes.

In Ontario there were originally thousands of hectares of long-grass prairie in the extreme southwest. After settlement by Europeans, the creation of numerous small farms with diverse crops, inefficient harvest methods and large weedy hedgerows greatly enhanced the potential for bobwhites, and resulted in the tremendous population increase. But, through the previous century, the trend has been away from pasture and summer fallow, and natural prairie has been all but eliminated.  Habitat fragmentation is also ongoing, and may be a more significant problem than overall habitat loss.

Biology

The nest is a shallow depression in the ground lined with plant material covered with grasses or vines arched over it for concealment. The mean clutch size is 12 to 16 eggs; incubation takes 23 to 24 days and the downy young can fly at an age of 6 or 7 days.  Only one brood is typically raised per season at the northern edge of the range.  Nests with eggs have been found from late May through mid-September, but the likelihood of successful hatching or fledging decreases as the season progresses.  Mean nesting losses may be 60 to 70 percent.  About 80 percent of the fall population consists of juvenile birds and the mean annual mortality of the species (including young birds) is about 80 percent.  Adult annual survival is about 30 percent.

Northern Bobwhite are nonmigratory, but in fall some birds disperse several kilometres.  Winter coveys require a minimum of 4.9 ha and rarely use more than 20 ha.

Population Sizes and Trends

What was probably a fairly small wild population in southwestern Ontario, prior to European settlement, underwent a considerable expansion following forest clearing in the early 1800s. The expanding population reached as far north as southern Georgian Bay and Kingston, although in any abundance, they were more limited to an area south of a line running from Goderich to Oshawa. Since reaching a population peak about the mid-1800s, numbers and extent of occurrence have steadily declined.

With declining populations, numerous releases of pen-reared birds were tried through much of the 20th century. But mortality rates of pen-reared birds have been found to be very high, and more recently such birds have been considered unsuitable for restocking.  In the early 1970s there were estimated to be about 1055 coveys of quail in Ontario, each containing several birds, primarily in Lambton, Middlesex, and Elgin counties.  Three successive severe winters in the late 1970s resulted in further population declines.

In the early 1980s, the breeding bird atlas and the subsequent rare breeding bird program 1989-1991 revealed a scattered distribution, with reports from only 79 squares (10X10 km) and a population estimate of between 232 and 1545 pairs.

In 1989-1990, an extensive mail survey in southwestern Ontario suggested the population had fallen to only about 185 quail in 16 coveys, and by 1994 it was considered that wild stock was probably persistent only in two disjunct areas in Aylmer and Chatham regions.

Data from three Breeding Bird Survey routes from 1966 to 2001 show a mean annual decline of 18.9 percent (p=0.04) in Ontario, a total decline of 99.9 percent over 35 years, or 88 percent per decade.  By the 1990s the population may have stabilized at very low levels of 200 to 250 birds.

Similar declines have occurred in the United States. In Breeding Bird Surveys from 1965 to 1995 declines of 70 to 90 percent were noted in 80 percent of the states in which it occurs.  Declines were greatest in the southeast, and less in the midwest, with numerous extinctions of local populations.

The second Ontario Breeding Bird Atlas (2001 - September 2003) has found Northern Bobwhite in only 19 squares after 3 years. The Extent of Occurrence has seemingly not changed, indeed the recent atlas effort has found bobwhite in 12 atlas squares in which they were not found in the 1980s.  Whether these new sites are the result of introduction efforts is unknown, but that is the most probable explanation.  On the other hand, bobwhite have not been found in 44 atlas squares that they were known to occur in during the 1980s, despite more than 20 hours’ search effort in each of these squares.

Atlassing results and other observations suggest that natural, viable populations now exist in Canada only on Walpole Island. Surveys there in 1999 and 2000 suggest a population of about 230 birds.

Limiting Factors and Threats

Habitat quality and quantity are the main factors limiting populations, as natural prairie habitat has all but disappeared and agricultural habitats have become less suitable through intensification.  Continued reintroduction efforts have been ineffective and may be contributing to the continuing population decline through the introduction of inappropriate genetic stock.

Special Significance of the Species

The Northern Bobwhite has one of the greatest public appeal ratings of any North American bird. It is a popular and challenging game bird in the U.S., on which more money is spent than any other. It has a most appealing song and appearance, making it an aesthetically valuable part of the rural atmosphere.

Existing Protection

The Northern Bobwhite was designated as Endangered by COSEWIC in 1994 (Page and Austen 1994). NatureServe lists the Northern Bobwhite as G5 (globally secure); the status in Ontario is S1S2 (imperilled).  There is no hunting season for the species within its native range in Ontario.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk.  On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species and include the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal organizations (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership, chaired by the Canadian Museum of Nature), three nonjurisdictional members and the co-chairs of the species specialist and the Aboriginal Traditional Knowledge subcommittees. The committee meets to consider status reports on candidate species.

Species : Any indigenous species, subspecies, variety, or geographically defined population of wild fauna and flora.

Extinct (X) : A species that no longer exists.

Extirpated (XT) : A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E) : A species facing imminent extirpation or extinction.

Threatened (T) : A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)* : A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

Not at Risk (NAR)* : A species that has been evaluated and found to be not at risk.

Data Deficient (DD)*** : A species for which there is insufficient scientific information to support status designation.

* : Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.

** : Formerly described as “Not In Any Category”, or “No Designation Required.”

*** : Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994.

Environment Canada Environnement Canada

Canadian Wildlife Service Service canadien de la faune

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.