Update Oct. 2004 - AOU announce split of Cackling Goose from Canada Goose.
Taxonomy of the Canada-type Geese.
Common Canada Goose Group
Dusky Canada Goose Group
Lesser Canada Goose Group
Cackling Canada Goose Group
Useful web sites.
Smaller 'Richardson's' Cackling Goose (C. hutchinsii hutchinsii) standing with a Canada Goose (C. canadensis canadensis). Besides the obvious difference in size, the Richardson's Goose shows a stubbier bill and broader pale fringing on the wing coverts and scapulars. 7 Jan 2005, Lido Beach, Nassau County, Long Island, New York. Photograph copyright of Angus Wilson ©2005.
(6 & 24 Oct 2004) In their 45th supplement to the Check-list of North American
Birds (Banks et al. 2004), the American Ornithologist's Union's Committee on
Classification and Nomenclature voted to split the Canada Goose (Branta
canadensis) into two species: Canada Goose (B. canadensis) and
Cackling Goose (Branta hutchinsii). As I understand it, recent work
on the evolution of the western forms using molecular approaches (e.g. Scribner
et al. 2003) contributed to this decision, although the split has been discussed
many times over the years. The
AOU has partitioned the generally accepted subspecies as follows:
Canada Goose (Branta canadensis): canadensis [Atlantic], interior [Interior], maxima [Giant], moffitti [Moffit's], parvipes [part of ‘Lesser complex’], fulva [Vancouver], and occidentalis [Dusky]. Collectively named Greater Canada Goose by BOURC (June 2005)
Cackling Goose (Branta hutchinsii): hutchinsii [Richardson's], asiatica [Bering (extinct)], leucopareia [Aleutian], taverneri [other part of ‘Lesser complex’], and minima. Collectively named Lesser Canada Goose by BOURC (June 2005)
A very positive aspect of this announcement is that it will stimulate much greater interest from birders in the identification and movements of the different ‘Canada’ populations within North America. This is good for conservation and will lead to better understanding of the identification issues. A downside is that field identification can be highly problematic and the split creates potential headaches for state/provincial records committees, regional compilers and the like. One of the major problems is the recent and wide-scale introduction of birds from western populations into eastern North America, with a resulting mixing of genes. Whether this leads to birds of intermediate appearance or good approximations of the western forms is anyones guess.
Even within wild, unmanipulated populations there are problems, due to lack of knowledge. For example, separation of taverneri and parvipes (classified as different species) under field conditions is not well understood and is said to be difficult - sometimes impossible - in the hand! The AOU nomenclature committee hints that this is a 'work in progress' (a truth behind many taxonomic decisions) and perhaps we will see some shuffling of populations from one species to the other as better information comes to light. The issue of 'environmentally-induced morphological variation' (also known as 'nutritional runting') further confounds the problems of field identification and needs to be addressed (e.g. Larsson et al. 1991; Leafloor et al. 1998).
The actual nomenclature of the split poses a number of headaches, not least because some of the same names have been used to mean different things at different times. A clear example is the decision to group the smaller forms under the name 'Cackling Goose', a choice that has already attracted significant criticism. Previously, many authors have used this name in specific reference to minima (and perhaps leucopareia). When reviewing past records or specimens, it is important to keep in mind the ever changing use of common names. In some respects, a move to new English names, without any history attachment, might have helped to clear the air and reflect the use of new methodologies, such as DNA sequence analysis.
challenges aside, I think we can anticipate much more discussion of 'white-cheeked'
geese by North American birders of and with luck, can look forward to significant
advances in field identification. One issue to keep in mind is that some identification
criteria have been developed from study of (apparant) vagrants rather than populations
within their normal nesting or wintering ranges. Indeed, in recent years, the
most detailed and innovative scrutiny has been given to birds outside the North
American continent (principally Britain, Ireland and the Low Countries), which
are by definition 'unknowns'. I think the splits will encourage birders in Canada,
the US and Mexico to examine their local goose flocks with a fresh eye. At a
minimum, this should give us a better sense of the normal variation in distinguishing
characters of the different taxa, something that is difficult for European goose
enthusiasts to address.
Banks, R. C., C. Cicero, J. L. Dunn, A. W. Kratter, P. C. Rasmussen, J. V. Remsen, J. D. Rising, D. F. Stotz. 2004. Forty-fifth supplement to the American Ornithologists' Union Check-list of North American Birds. Auk 121:985-995.
Larsson, J., and P. Forslund. 1991, Environmentally induced morphological variation in the Barnacle Goose, Branta leucopsis: Journal of Evolutionary Biology. 4 619–636.
Leafloor, J. O., C. D. Ankney, and D. H. Rusch. 1998, Environmental effects on body size of Canada Geese: Auk. 115 26–33.
Scribner, KT, Talbot, SL, Pearce, JM, Pierson, BJ, Bollinger, KS, and Derksena, DV. (2003) Phylogeography of Canada Geese (Branta Canadensis) in Western North America. Auk: Vol. 120, No. 3, pp. 889–907.
Taxonomy: There are many different opinions on the number of subspecies that exist and even suggestions that the group be split into 2-4 species.
Recent genetic studies of Canada geese support the existence of two major groups (Rusch et al. 1994). The large-bodied group (B. c. canadensis, interior, maxima, moffitti, fulva, occidentalis) which have a mainly continental distribution, and the small-bodied group (hutchinsii, taverneri, minima, leucopareia) which breed in coastal Alaska and Arctic Canada. This is a tentative arrangement only and more work is needed. The Dutch rarities committee (CDNA) has placed parvipes in the large-bodied group (and calling it 'Intermediate Canada Goose') but it is not clear how well this dividing line is supported (Millington and Gantlett 1999). On his web site David Sibley comments that the Canada Geese are, "rather arbitrarily divided here into six subspecies groups that differ in size, plumage, and voice; but all are connected by intermediate populations and identification can be difficult, even though the extremes seem like different species". Although some subspecies are thought to interbreed on a regular basis, it is unclear how this can be monitored given the imprecise field identification criteria available.
Identification: This topics needs a lot of work. As usual, birders in Europe have taken the lead, although their conclusions need confirmation on the breeding grounds in North America. The identification of vagrants is especially difficult because of the lack of other Canada Geese for comparison, poor understanding of variation within populations and the ever present specter of escapes (potentially of mixed origin). Careful study of each population on their breeding and wintering grounds should help to answer many of the questions that remain.
Canada Goose Group
As a broad generalization, the larger Canada Geese tend to breed to the south of smaller [Cackling] Canada's and are better represented in the interior and east of the continent.
Atlantic (or Eastern) Canada Goose (B. c. canadensis). Large size, long-necked. Black neck with white chinstrap. Body buff with paler underparts. Second largest form. Abundant breeder in SE Canada and NE USA. The Atlantic is similar to the Interior, but slightly larger. It is believed that this is the race introduced into western Europe and New Zealand.
Interior (or Central, or Hudson Bay, Todd’s) Canada Goose (B. c. interior). Large with very long neck and long, shallow bill. This race is very abundant in the wild and can be found throughout the eastern and central US. Breed in area south and east of Hudson Bay, also in Greenland NE Manitoba. Winter in the South-eastern USA and North-eastern seaboadr. Uncommon winter migrant to eastern Texas and coastal plain..
Moffitt's (or Western or Great Basin) Canada Goose (B. c. moffitti). Abundant. Found mostly west of the Rockies. Very similar to Atlantic and Interior forms. Some are lighter than Atlantic and Interior forms, but similar in size. Note that Palmer merged Moffitt's with Giant Canada Goose believing them closely related. Frequently nest in trees using abandoned hawk and heron nests. Common in Utah and Colorado, accounting for most of the breeders. Uncommon migrant to central and eastern Texas, some wintering on Gulf coast.
Canada Goose Group
Dusky Canada Goose (B. c. occidentalis). The darkest colored Canada geese in Alaska. Dusky Canada Geese average 6 to 8 pounds (2.7-3.6 kg), but males can weigh 10 pounds (4.5 kg) or more in spring. The population of Dusky Canada Geese has always been small, with the shortest migration of Alaskan Canada Geese populations. Nesting is limited to the Copper River Delta near Cordova. Most birds over winter in the rich grassy fields of Oregon's Willamette Valley and along the Columbia River near Portland, but a few stay farther north in coastal areas of Washington and British Columbia. The earthquake of 1964 produced an uplift and drying of their nesting grounds that initially helped Dusky Canada Geese increase to over 25,500 by 1979. However, long-term habitat changes favoring predators, such as brown bears and coyotes, have reduced dusky goose production, and the population has hovered between 10,000 and 18,000 since the 1980s. Many marked with red Collars.
Vancouver (or Queen Charlotte) Canada Goose (B. c. fulva). Weigh 6 to 10 pounds ((2.7-4.5 kg) during the fall, but males can weigh 12 to 14 pounds (5.5-6.4 kg) in spring. Darker breast than Moffitt's (Western). Generally don’t have collars. These geese are found in Southeast Alaska and British Columbia where most remain year-round. Unlike other Canada Geese, they nest in coastal forests and winter along marine waters. Their breeding biology is not well known because they are more secretive, frequently building nests and rearing broods in old growth spruce and hemlock forests, sometimes nesting in trees rather than on the ground. Clams, salmon eggs, and dead salmon supplement their vegetable diet in the winter.
Giant Canada Goose (B. c. maxima). This is a large goose with light grey or whitish breast, often with a characteristic white spot or band on the forehead separating the black crown from a band of black feathering above the bill. Was thought to be extinct but rediscovered in 1960s by Harold C. Hanson, a biologist of the Illinois Natural History Survey [Hanson, H.C. 1965. The giant Canada goose. Southern Illinois University Press, Carbondale. 226 pp.]. The largest of the all the Canada Geese, ganders (males) can weigh in excess of 23 pounds. Giant Canadas were restored to their former range in the Mississippi and Central flyways and are now said to breed in all states east of the Mississippi River.
Lesser Canada Goose Group
As a broad generalization, the smaller Canada Geese including all of the true Cackling Geese are tundra breeders and have a generally western distribution.
Lesser (or Athabasca) Canada Goose (B. c. parvipes). The two subspecies parvipes and taverneri are very similar and are often lumped as “Lesser Canada Geese”. They differ only slightly in size and color (Taverneri are smaller and darker-breasted). These two populations are the most widespread and abundant Canada goose subspecies in Alaska. B. c. parvipes nest in Cook Inlet and throughout river drainages between western and Interior Alaska and the Yukon Territory. Both subspecies winter primarily in Washington and Oregon. Relatively common in the Texas Panhandle during winter but rare migrants elsewhere in Texas. Migrants follow the Gulf of Alaska coastline or take a interior path along the Tanana River through British Columbia. Many B. c. parvipes are marked with blue collars, while Taverner’s are generally not marked.
Taverner's (or Alaskan) (B. c. taverneri). In Alaska, Taverner's are geese of coastal tundra, nesting just inland of cackling Canadas on the Yukon-Kuskokwim Delta and extending north to the Arctic Slope. Migrants gather at Izembek Lagoon near Cold Bay for a direct trans-Pacific flight. The literature suggests that Taverneri are longer-necked and longer-billed than parvipes or hutchinsii but this needs more careful study. Thought to be a rare migrant only to south and central states (e.g. Texas).
(or Baffin Island) Canada Goose (B. c. hutchinsii).
Small and dumpy with a square-looking head and short bill. Often short-legged.
Can appear silvery at distance.This is the smallest and the palest of the pale
forms, especially on the breast. Rarely a pale collar may be present, however,
often the lower border of the dark neck may simply appear diffuse as paler feathers
are admixed with the dark. Hutchinsii have a shorter and deeper bill
(appears stubby) than parvipes. Hutchinsii is known to intergrade with
parvipes in an overlap zone around Hudson Bay. The average hutchinsii
is larger than the largest minima, but that there is overlap. Breeding
in the arctic, Common migrant to central and eastern Texas wintering on the
coastal plain, Panhandle and South Plains. Also in northern Mexico.
Cackling Canada Goose Group
Cackling Cackling Goose (left) and Aleutian Canada Goose (right) photographed in the San Joaquin River National Wildlife Refuge near Modesto in Northern California. This is a primary wintering site for Aleutian Goose.Notice the dark, almost purplish plumage on the Cackler, especially the breast. On the Aleutian, the prominent white collar separating the black neck sock from the breast is typical. Photograph copyright of Les Chibana©2003.
Cackling Canada Goose (B. c. minima). The smallest subspecies, usually weighing 3 to 5 pounds (1.4-2.3 kg), and they have a distinctive high-pitched call. Cacklers nest only on the outer coast of the Yukon-Kuskokwim Delta in western Alaska and winter primarily in California's Central Valley. In recent years, increasing numbers of cacklers has wintered in western Oregon. Spring migration takes cacklers up the Pacific coast, with a stop in Cook Inlet marshes, through the Alaska Range to the nesting grounds. Fall migration includes staging on the upper Alaska Peninsula for several weeks, then a trans-oceanic flight to Oregon and California. Through the 1970s and early 1980s, overharvest and nest predation reduced the population from over 350,000 to about 30,000. Through a cooperative management effort among wildlife agencies and user groups from Alaska to California, cacklers rebounded to 160,000 by 1993 and are increasing. A few have been reported from eastern North America as well as Western Europe. In the Netherlands, minima regularly occurs in large flocks of Barnacle Geese, but has not been added to the Dutch list because of its westerly range, and the fact that many of the birds have had captive-style rings. Wild banded birds may have yellow collars. Wild birds are reported to be relatively tame.
Bering Canada Goose (B. c. asiatica). Another small subspecies, the Bering Canada Goose is now extinct. There is some confusion over its breeding range. Some sources list that it was found only on Bering Island in the Russian Commander Islands where as others include the Rat and Kurile Islands. Most or all wintered in Japan (Hokkaido and Honshu) (Kuroda 1939). The last credible observation is from Japan in 1929 in Japan, although there were rumors of birds nesting on Buldir Island in 1966. Extinction attibuted to hunting and introduction of rats to nesting islands. True taxonomic status uncertain and perhaps just a population within leucopareia.
Islands Canada Goose (B. c. ? - not asigned yet). Tiny
population (~125 birds) discovered in 1979 on Kiliktagik Island in the Semidi
Islands (Hatch and Hatch 1983). Morphometrically intermediate between Aleutian
and Taverner's Canada geese, these may constitute a distinct population or subspecies.
The Semidi birds winter near Pacific City, Tillamook County, Oregon (Martin
et al 1982). Unfortunately many goslings have deformities (inbreeding or pollution?)
and this may be a limiting factor on the population.
Aleutian Canada Goose (B.c. leucopareia). Show considerable variation in neck color (paler versus darker brown) and in whether or not they showed a full, partial, or non-existent whitish band across the base of the fore-neck (comment from Pau Lehman in Birding World). Most have black stripe through white on throat. Weigh 4 to 6 pounds (1.8-2.7 kg) and usually have a broader white ring at the base of their necks than other subspecies. These birds are seldom seen in Alaska outside of their Aleutian Islands breeding grounds and follow a coastal migration route through remote areas of the state and across the Gulf of Alaska on their way to and from their wintering grounds in California's Central Valley. Often begin the winter near Colusa, Colusa and Sutter counties arriving in late October to mid-December, then move to wintering areas near Modesto, Stanislaus Co., and Los Banos, MercedCo. using the Yolo Bypass and the Sacramento-San Joaquin delta en route. Migrants gather on the California coast near Crescent City, Del Norte County. They are also found on the Russian Commander Islands and Kuril Islands of Japan. Although they formerly nested throughout most of the Aleutian Islands, foxes introduced for fur farming between the 1750s and 1939 extirpated Aleutian Canadas from most islands. In 1967, there were fewer than 800 geese in the population and it was listed as an endangered species. An intensive rangewide recovery program and restocking of geese on fox-free islands has ensured their safety. In 1991, the growing population numbered over 7,000 and was downlisted to a threatened species. Most now nest on Buldir Island, with small numbers on Chagulak, Agattu, Nizki, and Kaliktagik islands. Many have colored leg bands and gray, green and blue collars.
Conservation Note: In 1967, the U.S. Fish and Wildlife Service added Aleutian [Canada] Goose to the list of U.S. endangered species under the Endangered Species Protection Act (32 FR 4001), and in 1970 to the list of foreign endangered species (35 FR 8495). Fox control programs on breeding islands and hunting closures in important wintering areas resulted in a rebounding of the populations. In 1990, the FWS downlisted all populations of the Aleutian Canada goose from endangered to threatened (55 FR 51106), noting that the species still faces threats from disease, predation, storms and habitat loss.
Many thanks to Les Chibana for allowing me to use his Aleutian and Cackling Goose photograph. Many people have discussed aspects of goose identification, taxonomy and distribution with me in the last few years, either directly or via forums such as ID-Frontiers. Thanks to you all!
Canada Geese occasionally display hints of a white collar, evident in the left hand bird. Corona Park, Queens Co., New York 19 December 2004. Photo copyright Angus Wilson.