By John Coluccy, Ph.D., DU Biologist
Skeins of Canada geese winging their way south in fall and north in spring have long symbolized the changing of seasons and a connection to far-off, wild places. However, in recent years, an increasing number of people throughout the U.S. are seeing Canada geese in their communities year round. The last time I checked, there were still four seasons. Is this some new breed of Canada goose that has lost migratory behavior? Who are these year-round residents, and where did they come from?
Canada geese that nest and reside most or all of the year in the Lower 48 are collectively referred to as "resident" Canada geese. For the most part, these populations are sedentary and only migrate southward if winter weather is severe enough to limit food and open water. However, some members of resident populations participate in molt migrations.
Historically, resident Canada goose populations were found in each of the four flyways. By the early 20th century, however, following European settlement, the birds were extirpated from much of their range as a result of unregulated hunting, egg collecting, and habitat destruction. In fact, the giant Canada goose, the largest subspecies of Canada goose, was thought to be extinct for nearly three decades, until Harold C. Hanson of the Illinois Natural History Survey rediscovered it in remnant populations during the early 1960s. Present-day resident Canada goose populations originated from privately maintained captive flocks originally used as live decoys and food.
These populations consist of several large subspecies, or races, of Canada geese. The Atlantic Flyway population is believed to be of mixed racial origin, including Atlantic, interior, western, and giant Canada geese. The Central Flyway population predominantly consists of western, giant, and interior Canada geese. In the Mississippi Flyway, most resident Canada geese are giant Canada geese, while those in the Pacific Flyway are western Canada geese.
Today, resident Canada geese can be found throughout their former range and beyond and are considered one of North America's greatest wildlife management success stories. In fact, these grand waterfowl can now be found nesting in every U.S. state. Most biologists believe there are currently more Canada geese in North America than at any other time in history, largely a result of increasing resident populations. Current estimates suggest there are approximately 3.6 million resident Canada geese in North America: 1.1 million in the Atlantic Flyway; 1.3 million in the Mississippi Flyway; 1.1 million in the Central Flyway; and 0.1 million in the Pacific Flyway. While most North American Canada goose populations are stable or slightly increasing, resident populations have increased dramatically, and they now outnumber or rival migrant populations in each of the flyways.
What is it about resident Canada goose populations that have enabled them to increase so rapidly? Why have they been so successful? As a group, Canada geese are long-lived, with relatively high survival rates and low reproductive rates. However, the larger-bodied subspecies (which make up residents) have the highest reproductive rates and highest survival rates. In comparison to migrant Canada geese, residents begin nesting at a younger age, have larger clutches, and enjoy relatively stable and high reproductive success (nest success and gosling survival).
Unlike their counterparts, which nest in the arctic and subarctic and whose annual production is often boom or bust due to weather conditions, resident Canada geese nest in temperate environments where weather and breeding habitat conditions are relatively stable. In addition, breeding seasons in temperate areas are prolonged, which provides opportunities for renesting in the event of nest failure. Resident Canada geese also do not face the energetic constraints associated with long-distance migration, and live in essentially predator-free environments, which likely enhances survival. Further, portions of resident populations that inhabit urban settings are afforded additional protection through the absence of waterfowl hunting in these areas.
Resident Canada geese are grazers by trade and prefer succulent new-growth grasses and sedges, but they sometimes grub for roots and tubers, as do snow geese. They also make extensive use of waste cereal grains during the fall and winter. Their adaptable feeding habits and ability to live near humans have allowed them to exploit contemporary habitats including urban landscapes with ponds surrounded by manicured grass, and agricultural landscapes with extensive croplands and pastures. In short, human-induced changes to the landscape have essentially provided resident Canada goose populations with ideal living conditions.
Increasing populations of resident Canada geese have provided a number of benefits. Resident Canada geese provide significant hunting opportunity where geese were once rare or absent, and have become an important component of the total Canada goose harvest in many areas. For example, during 1980-1986, resident geese in the Mississippi Flyway comprised about 15 percent of the total Canada goose harvest. This increased to 40 percent during 1986-1990, 57 percent dur- ing 1991-1995, and to nearly 75 percent during 1996-1998.
Due to their wide distribution, year-round presence, and tolerance of humans, resident geese also have become a very popular subject for wildlife observation. Oftentimes, resident geese provide ideal subject matter for ecological research, nature study, and environmental education, and they regularly appear in the media because they are so readily observable and can be found in close proximity to people.
Unfortunately, these blessings have been accompanied by some problems, particularly in urban areas where burgeoning resident Canada goose populations have resulted in increased conflicts between geese and humans. Problems caused by resident geese are varied and can affect or damage property, human health and safety, agriculture, and natural resources. Damage to property typically involves landscaping, walkways, docks, and beaches associated with parks, golf courses, and waterfront property, where accumulation of droppings and feathers, as well as overgrazing, reduces the aesthetic value and recreational use of these areas.
Surprisingly, resident Canada geese can pose human health and safety risks in a number of ways. At airports, large numbers of geese can create a serious threat to aircraft landing and taking off, and have been involved in a number of air strikes resulting in costly damage to aircraft and loss of human life. Excessive goose droppings can also pose a health risk to humans when fecal coliform counts reach unsafe levels in water used for swimming and drinking.
Additionally, during the nesting and brood-rearing period, aggressive geese have chased and even injured people. Impacts to agriculture and natural resources include crop damage, overgrazing of pastureland, and degradation of water quality. Droppings from large concentrations of geese can lead to excessive nutrient levels in ponds and lakes.
Further problems occur as a result of interactions between resident and migrant Canada goose populations. Although migrant and resident Canada geese occupy discrete geographic locations during the nesting period, these groups occur together on staging and wintering areas, and molt-migrant resident geese occupy breeding areas of arctic and subarctic nesting geese for a portion of the summer. The mixing of different Canada goose populations in time and space in some cases has hampered the ability of wildlife managers to accurately estimate populations of migrant geese. Increasing numbers of molt-migrant resident geese also may be competing with migrant geese for preferred food resources on arctic and subarctic breeding and brood-rearing areas. It also has been suggested that resident populations may act as decoys to migrant geese during fall and winter, altering their distribution and habitat use.
Despite these problems, resident Canada geese continue to be a valuable resource shared among many people. They add beauty and diversity to the environment and increase recreational opportunities wherever they are found. These majestic birds provide us with a connection to the wild even in urban and suburban settings.