Canada Geese

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Human influences on Canada Geese populations

Giant Canada Geese (Branta Canadensis maxima) are another example of successful wildlife management. Canada Geese lived in the Midwestern United States until they were extirpated by the early 1900s due to habitat loss and over hunting. Management programs were put in place and the species population has been increasing in North America since 1940. In fact, programs have been so successful at reintroducing the Canada Geese that their range now spreads throughout much of the U.S. These birds live in a broad range of habitats, but prefer locations near permanent water with a clear view in all directions. This includes golf courses, lawns in subdivisions, and city lakes and parks (Mowbray et al. 2002). These geese have greatly benefited from anthropogenic landscape changes because suburban ponds and golf courses provide the birds food, water, and protection (MDNR). Some Canada Geese have even stopped migrating and now live year-round at locations (Mowbray et al. 2002).

About 2 million Canada Geese are hunted each year in the U.S., making it one of the top waterfowls harvested in North America. Hunting cannot be used as an effective management control in urbanized areas, however. These birds are now so abundant in many urban areas that some find them to be pests because of their droppings, crop damage, sometimes-aggressive behavior towards humans, and accidents with aircrafts (Mowbray et al. 2002).

Influences of Canada Geese on ecosystems

Canada Geese may negatively influence pond ecosystems. Many studies have documented how increasing numbers of Giant Canada Geese may limit populations of other waterfowl. For instance, Giant Canada Geese in Ontario degraded necessary brood-rearing habitat for Interior Canada Geese (Mowbray et al. 2002). They have also been associated with declining populations of Atlantic Canada Geese and poor gosling growth of Interior Canada Geese (Post et al. 1998).

Canada Geese may also reduce the growth rates of plants and influence plant composition. For instance, a study in Connecticut found that Canada Geese preferred Kentucky bluegrass. Because the birds overgrazed the grass species, they altered the plant composition of the study site (Conover 1991).

Canada Geese may also decrease water quality. Over fertilization and contamination of lakes, ponds, and reservoirs have been linked to increasing geese populations. For instance, in Bosque del Apache National Wildlife Refuge in New Mexico, geese were responsible for a 40% increase in nitrogen and 75% increase in phosphorus in some wetland ponds (Kitchell et al. 1999). Overall, dense populations of Giant Canada Geese may negatively affect some ecosystems.

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Photo credits
Land use change: www.geog.umd.edu/borealfire/indonesia.html
White-tailed deer: www.nraila.org/issues/Articles/Read.aspx?ID=165
Coyote:www.unitedwildlife.com/AnimalsCoyotes.html
Canada Geese: MC Cassino, www.markcassino.com/b2evolution/index.php?m=2006
Canada Geese on golf course: www.ngpc.state.ne.us/nebland/articles/hunting/boom.asp
Flock of Canada Geese: www.ducks.org/Members_Only/Wallpaper/1976/DUWallpaper.html