Branta canadensis

History of Spread

Branta canadensis (Canada Geese) have been present since before European colonization in the Chesapeake Bay region and the Atlantic Coast of North America as wintering birds and migrants. However, this species did not become a widespread breeding bird and resident on the Atlantic coast and much of North America until the mid-20th century (Sauer et al. 1996). Breeding grounds of the original Chesapeake Bay wintering subspecies, B. c. canadensis and B. c. interior, are in Canada north of the St. Lawrence River and Great Lakes (Johnsgard 1978; Peterson 1980).

Resident nonmigratory Canada geese on the east Coast appear to be predominantly one subspecies, B. c. maxima (Giant Canada Goose) (Allan et al. 1995; Allin 1980; Johnsgard 1978; Pottie and Heusman 1979), which was originally native to the Great Plains and Great Lakes Basin, and was at one time believed to be extinct (Hanson 1965; Johnsgard 1978). The original breeding range of B. c. maxima (Giant Canada Goose) stretched from the shores of Lake Erie and the eastern Ohio River valley, south to the Ohio-Mississippi River junction, and west on the Great Plains to Rocky mountain foothills from Alberta to CO (Hanson 1965).

In its native Midwest, B. c. maxima breeds in local wetlands and then migrates in an irregular fashion Newly molted (molt-migrant) birds may migrate northward for feeding, to Hudson Bay, and the Arctic Ocean, and then southward to the Mississippi River Valley, Gulf Coast, and southern Great Plains for wintering (Hanson 1965). However, many midwestern populations winter in northern areas, especially in urban regions where food is plentiful (Addison and Amernic 1983; Hanson 1965; Laycock 1982). This subspecies appears to be more tolerant of people than other B. canadensis subspecies, a trait that may have contributed to its near-extinction but also to its semi-domestication by Indians, and later by European settlers and 20th century suburbanites (Hanson 1965).

In the early 20th century, populations of B. c. maxima appeared to be endangered, as a result of over-hunting and conversion of prairies and pothole marshes to farmland. Extensive game-farm rearing of B. c. maxima was undertaken by government agencies and private individuals to restore resident Branta canadensis populations within their native midwestern range (Hanson 1965; Mikula et al. 1970; Lumsden 1981). Branta canadensis maxima were also widely introduced to new areas as well. For example, 167 B. c. maxima were released in RI between 1958 and 1971 (Allin 1980). Another source of resident birds was the release of captive birds kept as live decoys, after 1918, when this practice became illegal. (Murray 1952; Pottie and Heusmann 1979).

By 1962, B. c. maxima were nesting along the Atlantic coast from ME to FL (Johnsgard 1978; Allin 1980). In the 1960's, many resident flocks were established by deliberate release of B. c. maxima in wildlife refuges in southeastern states, including TN, GA, and FL (Oberheu 1973). An additional source of resident B. canadensis, of originally migratory stock (B. c. canadensis and B. c. interior), was injured birds, which were unable to migrate, but bred in the relative protection of wildlife refuges (e.g., Wass 1972). However, morphometric studies of resident Canada Geese populations suggest that most of the birds fit the criteria for B. c. maxima, although some interbreeding between subspecies may have occurred (Pottie and Heusmann 1979; Limpert 1981).

By the 1980's, populations in suburban areas of the Great Lakes region and the eastern United States were dense enough to be regarded as a problem (Addison and Amernic 1983; Conover and Chasko 1984; Laycock 1982). Highest densities of breeding geese on the Atlantic seaboard now occur from southeast PA to southwest CT, in the New York City suburban area (Sauer et al. 1996).

Branta canadensis is a relatively new breeding bird in the Chesapeake Bay region. It was not mentioned as a breeder for MD by Kirkwood (1895), for VA by Bailey (1913), or for Washington DC (Cooke 1908; Cooke 1921). Forty-one non-migratory B. c. maxima were introduced to Blackwater National Wildlife Refuge, Dorchester County, from the Midwest. In 1946, a flock of breeding B. c. maxima was established on the lands of the Patuxent Wildlife Research Center, in Prince George County MD, from eight resident birds captured at the Blackwater National Wildlife Refuge. Geese from the Patuxent flock, examined 30 years later, were closest to B. c. maxima in their measurements (Limpert 1981). This Patuxent population appears to be the source of most of the resident birds in the Washington DC area (Robbins and Blom 1996).

Additional birds in the Chesapeake Bay region probably resulted from releases of birds used as live decoys. A pair of B. canadensis nesting in 1940 on Ragged Island, Back Bay, south of Virginia Beach VA, were 'probably of decoy stock' (Murray 1952). Other VA breeding reports are: Hog Island Wildlife Management Area, James River (1952), Chincoteague (1971), Hopewell Wildlife Management Area, James River (1977). Flocks were spending the summer in the vicinities of Chincoteague, Hopewell, and Alexandria, and presumably breeding in these areas (Checklist Committee 1979; Wass 1972). Nonmigratory B. canadensis now appear to be common as breeders throughout the Chesapeake Bay region (Sauer et al. 1996; Fofonoff personal observations 1995-1996; Robbins and Blom 1996).

History References - Addison and Amernic 1983; Allan et al. 1996; Allin 1980; Bailey 1913; Checklist Committee 1979; Conover and Chasko 1984;; Cooke 1908; Cooke 1921; Hanson 1965; Johnsgard 1978; Kirkwood 1895; Laycock 1982; Lumsden 1981; Mikula et al. 1970; Murray 1952; Oberheu 1973; Pottie and Heusmann 1979; Robbins and Blom 1996; Sauer et al. 1996; Van Velsen 1967; Wass 1972

Invasion Comments