The Canada Goose (Branta Canadensis)

The Canada Goose – Branta Canadensis

Canada geese (Branta canadensis) at Westwood Lake, Nanaimo, BC

The Canada goose (Branta Canadensis) is a prominent, widespread species found across North America. It is a very conspicuous bird, its large size and loud honking call make it hard to miss. It is a bird that is very familiar to many people, particularly because large numbers of geese have become well-adapted to urban areas such as lawns, golf courses, sports fields, airports, and urban bodies of water (Smith et al. 1999; Cornell University 2015). As shown in Figure 1, it occurs throughout most of North America and into southwestern Greenland; also, introduced populations exist in many parts of Western Europe (Butchart et al. 2010).

Range of the Canada goose in North America

Range of the Canada goose in North America [Source]

The Canada goose is easily identifiable by its long black neck and distinct white cheek patches. The body is usually mottled brown, with lighter undertones and a darker back; the Canada goose has black webbed feet, a white rump, and black tail-feathers. Canada geese are sexually monomorphic, meaning both sexes exhibit the same plumage, but males are typically slightly larger than females (Smith et al. 1999). There is a trend in Canada goose populations in which body size decreases in northern populations and body colour becomes darker in western populations (Cornell University 2015). The Canada goose typically has a body length between 76 – 110 cm, a wingspan of 127 – 170 cm, and weighs between 3.0 – 9.0 kg (Cornell University 2015). In general, Canada geese are larger than other waterfowl, with the exception of swans (USFWS 2015).

Canada geese (branta canadensis) and Tundra Swans (Cygnus columbianus)

Canada geese (Branta canadensis) and Tundra Swans (Cygnus columbianus)

Canada geese can be found in a wide variety of habitats, such as lakes, rivers, tundra, bogs, swamps, marshland, estuaries, agricultural land, and near shore marine areas (Johnson 2011; Cornell University 2015). They feed on a wide variety of foods, including grasses, shoots, leaves and aquatic plants; they also take advantage of waste crops such as grain, beans, or corn (Ducks Unlimited 2015; University of Auckland 2010). In recent decades, Canada geese have become well adapted to urban areas (Regional Canada Goose Management Strategy (RCGMS) 2012) . This adaptation greatly reduces exposure to predation, and also reduces mortality due to hunting because hunting generally does not occur within urban areas; this combination has resulted in enormous population growth over the past four decades (University of Auckland 2010; State of Connecticut 2012).

Population growth of Canada geese in Greater Victoria [Source]

Population growth of Canada geese in Greater Victoria (1958-2010) [Source]

The integration of Canada geese into the urban landscape was the result of introduction programs that started in the 1960s (Isaac-Renton et al. 2010; RCGMS 2012). These introduction programs were started because populations across North America were greatly reduced due to market hunting prior to the 1900s (University of Connecticut 2012). In fact, the largest subspecies, the giant Canada goose (B. c. maxima) was thought to have been hunted to extinction until it was rediscovered in 1962 (Brakhage 1965). With the aid of reintroduction programs and restricted hunting practices, the giant Canada goose, along with most other subspecies, have made an impressive population resurgence (Isaac-Renten et al. 2010; Mowbray et al. 2002).

Canada geese are adaptable to a wide variety of habitats

Canada geese are adaptable to a wide variety of habitats

There are currently seven recognized subspecies of the Canada goose throughout North America (RCGMS 2012; Cornell University 2015). Formerly there were 11 subspecies, but in 2004 it was agreed that the very similarly coloured but much smaller-bodied “cackling Canada goose” subspecies were indeed separate species. These smaller-bodied species were designated the “cackling goose” (Branta hutchinsii), of which there are four subspecies (Birdweb 2015; Cornell University 2015) On the Pacific Coast, there are 5 subspecies of the Canada goose (Branta canadensis): the lesser Canada goose (B. c. parvipes), the Vancouver Canada goose (B. c. fulva), the western Canada goose (B. c. moffitti), and the dusky Canada goose (B. c. occidentalis) (Pearce and Bollinger 2003). Distinguishing between the subspecies in the field isn’t easy, although the lesser Canada goose is the smallest amongst the Pacific subspecies (Sibley 2007), and the dusky Canada goose has the darkest coloured body (Pearce and Bollinger 2003). Culmen length and total tarsus length can be used to definitively determine subspecies, because using body colour is not reliable (Pearce and Bollinger 2003).

Culmen length is from the tip of the bill to where it meets the forehead

Tarsus length

The Pacific subspecies of Canada geese can be found along the Pacific coast from Alaska to California, although some do not range as far north or south as others (Bromley and Rothe 2003). Populations of Canada geese on the Pacific Coast are stable to increasing, the exception to this trend is the dusky Canada goose, which has experienced a 40 – 50% decrease in its breeding population since the 1970s (Bromley and Rothe 2003). Overall, the North American population has experienced an average increase of 10.78% per year over the past 40 years (USGS 2012).

Canada goose (branta canadensis) with cackling goose (branta hutchinsii)

As waterfowl, Canada geese require open water as part of their habitat. This factor, along with availability of food, dictates when migratory populations of Canada geese migrate north in the spring or south in the fall (Ducks Unlimited 2015). Many populations will winter just as far south as need be to obtain open water, while others migrate as far south as subtropical areas (Geese Peace unkown; University of Wisconsin 2007; Cornell University 2015). Although some populations may migrate the entire length of North America, most resident populations do not migrate at all; this is because geese nest in the area where they are born, so introduced populations do not have the urge to migrate (Brakhage 1965; Geese Peace unkown). In the fall, migration can cover up to 1000 kilometers in a single day; however, spring migration typically occurs in a series of stopovers so that the geese can build up fat reserves for breeding (Ducks Unlimited 2015).

Much of what is known about Canada geese is due to banding, which allows biologists to track their distribution and movement

Canada geese typically reach breeding maturity at 3 years of age, although 2 years is not uncommon, and mate for life (Smith et al. 1999). Canada goose females return to the same area where they were hatched. They construct a nest on the ground and line it with their own down; nests are usually located within 150 feet of a water body, and islands are often favoured (Smith et al. 1999). Nesting occurs between late March to early May, depending on latitude and weather conditions (Smith et al. 1999). On average, 5 eggs are laid and incubated for 28 days. During this time, the male goose closely guards the nest. Once hatched, the goslings spend approximately 24 hours in the nest before abandoning it (Brakhage 1965). The goslings are then closely guarded by their parents and are raised in and around the chosen body of water. Goslings usually fledge within 4-7 weeks, depending on size of the subspecies, with the smaller subspecies fledging earlier (National Audubon Society 2015). During this time, the parents also moult their primary flight feathers and are flightless, but complete their moult at the same time as the juvenile geese are ready to fly (Link 2015). On average, Canada geese live to be 12 years of age, with a range of 10 – 25 years (Johnson 2011); however, the oldest wild goose on record was 30 years 4 months old (USFWS 2015).

(For list of references, please see Post #2: Ecological Impacts and Management of Canada Geese (Branta Canadensis) on Vancouver Island, BC)

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Ecological Impacts and Management of the Canada Goose (Branta canadensis) on Vancouver Island, BC

Ecological Impacts and Management of Canada Geese (Branta Canadensis) on Vancouver Island, BC

The Canada goose (Branta canadensis) is a common sight along the British Columbia coast, particularly around Central and Southern Vancouver Island. However, this was not always the case. Canada geese were only migrants and winter visitors before a few geese were introduced in the 1920s and 30s (Dawe and Stewart 2010). These early introduction attempts yielded a small resident population of birds in the Victoria area, but it wasn’t until more intense introduction programs took place in the 1970s and 80s that the population really started to grow (Dawe and Stewart 2010). These introduction attempts were made by both government and private organizations in an effort to increase hunting opportunities around the island. Today, the population of resident geese is estimated to be 15,000 and is growing rapidly; the geese are often considered nuisances, and degradation of coastal and estuarine ecosystems, along with crops and agricultural land, is a major concern (Dawe and Stewart 2010; Isaac-Renton et al. 2010; RCGMS 2012).

A classic Canada goose nest

Canada geese imprint on the area they were hatched and return to breed in that same area themselves. The combination of this life history trait with introduction programs has resulted in the growth of “resident” flocks which don’t have the urge to migrate (RCGMS 2012; Dawe and Stewart 2010; Dawe et al. 2011). This is a familiar problem for most of North America, and Vancouver Island is no exception. Resident geese have higher breeding success because they aren’t subjected to the high energy demands of migration; this allows more energy to be used for reproduction than their migratory counterparts (Dawe et al. 2011).

Part of the reason for the population surge of Canada geese is their adaptability

For example, no Canada geese were observed in the Englishman River estuary in June of 1974; however, by 2007 at least 73 nesting pairs were observed. The first pair of nesting Canada geese were observed on the Little Qualicum River estuary in the summer of 1984, and by 2010 at least 45 pairs were observed nesting (Dawe and Stewart 2010). Although these populations don’t seem excessive, it is clear that they are growing quickly. In the opinion of biologist Neil Dawe, the population of geese on Vancouver Island has already exceeded the carrying capacity for the region (Hume 2010; Dawe et al. 2011). Dawe et al. (2011) found that geese are altering the floral composition of East Coast Vancouver Island estuaries. Alterations of the plant community has caused erosion, affected nutrient-cycling, shading, and soil salinity levels. Changes to these factors has altered ecosystem functioning altogether, perhaps permanently (Dawe et al. 2011).

Example 1 of damage inflicted by Canada goose grazing, Little Qualicum River Estuary, BC (top photo August 1978; bottom photo August 2005)

Example 1 of damage inflicted by Canada goose grazing, Little Qualicum River Estuary, BC (top photo August 1978; bottom photo August 2005) [Source]

These changes have wide-ranging effects, which can be detrimental to all sorts of native species from invertebrates to fish to mammals and to other avifauna. Isaac-Renton et al (2010) found that grazing Canada geese in the nearby gulf islands are allowing the introduction of exotic annual grasses, which has negatively impacted the diversity of native plant species in maritime meadows. These ecosystems are already considered threatened, so the damage incurred by the relatively new resident Canada geese is highly unwelcome.

Damage inflicted by Canada goose grazing; Little Qualicum River estuary (top photo August 1980; bottom photo August 2005)

Example 2 of damage inflicted by Canada goose grazing, Little Qualicum River Estuary, BC (top photo August 1980; bottom photo August 2005) [Source]

In the Capital Region of Vancouver Island, a “Regional Canada Goose Management Strategy” (RCGMS) is being developed to address the surging population of geese. In this region, goose-related problems include damage to agricultural crops, hazards at the Victoria International Airport, concerns over water quality, human/goose conflicts in parks, and environmental degradation of sensitive ecosystems (RCGMS 2012).

A brood of Canada geese

The overabundance of Canada geese on Vancouver Island poses a special management problem. Along with human/goose conflicts such as crop damage and airport safety, the geese are causing damage to local ecosystems, which in turn is affecting native flora and fauna (Dawe and Stewart 2010; Isaac-Renton et al. 2010; RCGMS 2012). At the very least, long-term stabilization of the population is needed to ensure that these problems don’t become worse. However, although introduced, euthanization of resident geese to rectify these problems is frowned upon by the majority of the general public (Braband and Clark 1991; Lefebvre unknown; Hume 2010). Biologist Neil Dawe believes that in order to protect local estuarine ecosystems, Canada geese may have to be eradicated altogether (Hume 2010). In reality, despite damage to local ecosystems clearly caused by the geese, public opposition to a cull makes it an unlikely solution. This means that it is up to wildlife managers to bring the population growth under control, which can be done through hunting and egg addling (RCGMS 2012). Hunting is another management tool, however many of the resident goose populations utilize urban areas, where hunting isn’t an option due to nearby proximity of houses and bystanders (RCGMS 2012; Smith et al. 1999). Hazing of geese to chase them out of areas where they are a problem isn’t a long-term solution, as the geese just become a problem elsewhere and/or eventually return to the original area (RCGMS 2012; Smith et al. 1999). The Regional Canada Goose Management Strategy (2012) predicts that the growth in the population of Canada geese in the Capital Region can be curbed through annual egg addling and removing just 100 adult birds per year by hunting. In fact, if carried out on an annual basis, this management strategy would eventually cause a decrease in the population (RCGMS 2012).

Projected population by the Regional Canada Goose Management Strategy [Source]

Projected population by the Regional Canada Goose Management Strategy [Source]

As for the remainder of the Southeast Coast of Vancouver Island, it is likely that similar measures will need to be implemented in order to control population growth. In some areas, the population will at least have to be reduced to a point that meets the carrying capacity of the local ecosystem (Dawe et al. 2011). Canada geese are a familiar sight that many people enjoy and associate with nature. However, special attention should be directed towards their management to ensure that the geese don’t continue to degrade important habitats for other species, particularly because they are introduced to the region.

 

References (Posts 1 & 2)

Smith, A.E., Craven, S.R., and Curtis, P. D. 1999. Managing Canada geese in urban environments. Jack Berryman Institute Publication 16, and Cornell University Cooperative Extension, Ithaca, N.Y.; [cited 2015 Sep 25]. Available from: https://ecommons.cornell.edu/bitstream/handle/1813/66/Managing%20Canada%20Geese;jsessionid=15B926B1D86681CE745746849992342A?sequence=2

Cornell University [Internet]. 2015. Canada goose – branta canadensis: life history; Ithaca, NY: Cornell Lab of Ornithology; [cited 2015 Sep 25]. Available from: http://www.allaboutbirds.org/guide/Canada_Goose/lifehistory

Butchart, S., Ekstrom, J., Khwaja, N., and Pilgrim, J. [Internet]. 2015. Birdlife international species factsheet: canada goose – branta canadensis; [cited 2015 Sep 25]. Available from: http://www.birdlife.org/datazone/speciesfactsheet.php?id=384

USFWS [Internet]. 2015. Swans and geese; [cited 2015 Sep 26]. Available from: http://flyways.us/duck-identification-resources/swans-and-geese

Johnson, S. [Internet]. 2011. Beauty of birds: canada geese; [cited 2015 Sep 26]. Available from: http://beautyofbirds.com/canadageese.html

Ducks Unlimitied [Internet]. 2015. Learn about wetlands: canada goose – branta canadensis; Stonewall, MB: Ducks Unlimited Canada; [cited 2015 Sep 28]. Available from: http://www.ducks.ca/learn-about-wetlands/wildlife/canada-goose/

University of Auckland [Internet]. 2010. Branta canadensis (bird); Auckland, NZ: Auckland University; [cited 2015 Sep 29]. Available from: http://www.issg.org/database/species/ecology.asp?si=1427&lang=EN

State of Connecticut [Internet]. 2012. Wildlife in connecticut: wildlife fact sheet: canada goose – branta canadensis; Hartford, CT: State of Connecticut; [cited 2015 Oct 1]. Available from: http://www.ct.gov/deep/lib/deep/wildlife/pdf_files/outreach/fact_sheets/cdgoose.pdf

Isaac-Renton, M., Bennett, J.R., Best, R.J., Arcese, P. 2010. Effects of introduced canada geese (branta canadensis) on native plant communities of the southern gulf islands, british columbia; Ecoscience [Internet]; [cited 2015 Oct 1]; 17(4): 394-399. Available from: http://www.bioone.org/doi/full/10.2980/17-4-3332 doi: http://dx.doi.org/10.2980/17-4-3332

Brakhage, G.K. 1965. Biology and behavior of tub-nesting canada geese; J Wildlife Manage [Internet]; [cited 2015 Oct 1]; 29(4): 751-771. Available from: http://www.jstor.org/stable/3798552?pq-origsite=summon&seq=1-%20page_scan_tab_contents#page_scan_tab_contents doi: 10.2307/3798552

Mowbray, T.B., Ely, C.R., Sedinger, J.S., Trost, R.E. [Internet]. 2002. The birds of north america online: canada goose – branta canadensis; Ithaca, NY: Cornell Lab of Ornithology; [cited 2015 Oct 3]. Available from: http://bna.birds.cornell.edu/bna/species/682/articles/introduction

Birdweb [Internet]. 2015. Canada goose – branta canadensis; Seattle, WA: Seattle Audubon Society; [cited 2015 Oct 3]. Available from: http://www.seattleaudubon.org/birdweb/bird/canada_goose

Cornell University [Internet]. 2015. Cackling goose – branta hutchinsii: life history; Ithaca, NY: Cornell Lab of Ornithology; [cited 2015 Oct 5]. Available from: http://www.allaboutbirds.org/guide/Cackling_Goose/lifehistory

Pearce, J.M., Bollinger, K.S. 2003. Morphological traits of pacific flyway canada geese as an aid to subspecies identification and management; J Field Ornithol [Internet]; [cited 2015 Oct 2]; 74(4): 357-359. Available from: http://www.jstor.org/stable/4131045?pq-origsite=summon&seq=1-%20page_scan_tab_contents#page_scan_tab_contents

Sibley, D. [Internet]. 2007. Distinguishing cackling and canada goose; unknown: Sibley Guides; [cited 2015 Oct 4]. Available from: http://www.sibleyguides.com/2007/07/identification-of-cackling-and-canada-goose/

Bromley, R.G., Rothe, T.C., 2003. Conservation assessment for the dusky canada goose (branta canadensis occidentalis baird); Portland, OR: US Department of Agriculture, Forest Service: Pacific Northwest Research Station [Internet]; [cited 2015 Oct 4]. Available from: http://www.arlis.org/docs/vol1/54830739.pdf

USGS [Internet]. 2012. North america breeding survey trend results: canada goose – branta canadensis; [cited 2015 Oct 4]. Available from: http://www.mbr-pwrc.usgs.gov/cgi-bin/atlasa12.pl?01720&1&12&csrfmiddlewaretoken=3YKakk7LxT2ki6NSpl4mstudYCqdW02C

GeesePeace [Internet]. Date unknown. Why geese do not migrate; [cited 2015 Oct 6]. Available from: http://www.geesepeace.com/whygeesedonotmigrate.html

University of Wisconsin [Internet]. 2007. Migratory birds of the great lakes: canada goose migration – page 2; Madison, WI: University of Wisconsin; [cited 2015 Oct 4]. Available from: http://www.seagrant.wisc.edu/birds/Canada_Goose_migration2.html

National Audubon Society [Internet]. 2015. Guide to north american birds: canada goose – branta canadensis; [cited 2015 Oct 4]. Available from: http://www.audubon.org/field-guide/bird/canada-goose

Link, R. [Internet]. 2015. Living with wildlife: canada geese; Olympia, WA: Washington Department of Fish and Wildlife; [cited 2015 Oct 4]. Available from: http://wdfw.wa.gov/living/canada_geese.html

Dawe, N.K., Stewart, A.C. 2010. The Canada goose (branta canadensis) on vancouver island, british columbia; Vancouver, BC: British Columbia Birds, J BC Field Ornithol [Internet]; [cited 2015 Oct 20]; 20: 24-40. Available from: http://www.academia.edu/12104403/The_Canada_Goose_Branta_canadensis_on_Vancouver_Island_British_Columbia._British_Columbia_Birds_20_24-40

Dawe, N.K., Boyd, W.S., Buechert, R., Stewart, A.C. 2011. Recent, significant changes to the native marsh vegetation of the little qualicum river estuary, british Columbia; a case of too many canada geese (branta canadensis)?; Vancouver, BC: British Columbia Birds, J BC Field Ornithol [Internet]; [cited 2015 Oct 20]; 21: 11-31. Available from: http://www.researchgate.net/publication/275032471_Recent_significant_changes_to_the_native_marsh_vegetation_of_the_Little_Qualicum_River_estuary_British_Columbia_a_case_of_too_many_Canada_Geese_%28Branta_canadensis%29

Hume, M. 2010 Dec 21. Bird lover advocates eradication of canada geese. Globe and Mail: Env. Sect. [Internet]; [cited 2015 Oct 20]. Available from: http://www.theglobeandmail.com/news/british-columbia/bird-lover-advocates-eradication-of-canada-geese/article560256/

Braband, L.A., Clark, K.D. 1991. Perspectives on wildlife nuisance control: results of a wildlife damage control firm’s customer survey; Lincolm, NE: University of Nebraska [Internet]; [cited 2015 Oct 21]. Available from: http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1007&context=ewdcc5

Lefebvre, J. [date unknown]. Wildlife management responses within the city of calgary; Calgary, AB: University of Calgary [Internet]; [cited 2015 Oct 21]. Available from: http://www.ucalgary.ca/ev/designresearch/projects/EVDS663/wildlifemanagement.pdf

Lefebvre, J. [date unknown]. Wildlife management responses within the city of calgary; Calgary, AB: University of Calgary [Internet]; [cited 2015 Oct 21]. Available from: http://www.ucalgary.ca/ev/designresearch/projects/EVDS663/wildlifemanagement.pdf

 

 

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