Blackwater National Wildlife Refuge
Northeast Region
2145 Key Wallace Dr
Cambridge, MD 21613
(410) 228-2677

Canada Geese at Blackwater

The Arrival

The advance guard arrives in late September, and numbers steadily increase throughout October until the current peak concentration of 35,000 is reached in early November. About 25,000 geese remain at Blackwater all winter, while others use the Refuge as a resting and feeding area on their way farther south.

Canada Geese. Credit: Mary Konchar

Although it is hard to imagine the Refuge without Canada geese, between 1933 and 1938 none wintered on Blackwater. Goose concentrations on the Delmarva Peninsula began increasing in the 1940s due to an increased food supply resulting from the widespread adoption of the mechanized corn picker that "wasted" much more grain than was left in the fields when corn was harvested by hand. From a maximum of 5,000 geese in 1942, the populations increased at Blackwater until they peaked at 105,000 in 1963. Due to the significant loss of wetlands and thousands of acres of three-square bulrush marshes, drought conditions, reduction in the Refuge's cropland acreage, severely depressed reproductive success on the breeding grounds, and increased hunting pressure on the Eastern shore, the Canada goose population declined to approximately 20,000 by 1992. Recent improvements in management practices, however, are helping to restore numbers to the objective level of 50,000.

Blackwater Management

In conjunction with the North American Waterfowl Management Plan, Blackwater NWR is directing its management effort towards maintaining and improving habitat to help restore diminishing waterfowl populations. Over 12,000 acres of natural brackish marsh and open water provide resting and feeding areas for migratory waterfowl. The primary plant species in these areas highly valued for food for Canada geese is the Olney three-square bulrush.

Since 1992, more than 460 acres of croplands have been managed annually to provide a diversity of food sources high in carbohydrates for energy and in proteins for molting, juvenile body growth, and to help waterfowl return to the breeding grounds with sufficient reserves for reproduction. Refuge-planted crops high in fat-building carbohydrates include millet, soybeans, sorghum (or milo), corn, and buckwheat; also several types of clover, winter rye grass, and winter wheat provide excellent sources of green browse.

Natural vegetation is also provided as a food source through a program called "moist soil management." Water is gradually removed from approximately 300 acres of freshwater impoundments in the spring to provide a wet seed bed for germination of natural vegetation. The plants also harbor higher insect populations which, when flooded in the fall, provide important protein sources for feeding waterfowl.

Canada geese. Credit: Bob Quinn

Feeding Habits and Movement

Geese feed on tender shoots and roots of aquatic plants in the marshes and on grain and "green browse" in the fields. An adult goose needs an average of one-half pound of food a day -- less in warm weather and more during cold periods and prior to long distance flights.

In extreme cold and wind, geese will sit out the weather and not eat. They save energy by not flying. While waiting, they tuck their feet and bills into their soft down feathers. Extremities which are not covered with insulation lose heat rapidly and deplete energy reserves needed for migration, nesting, and molting in the spring.

When daytime hunting pressures in the area surrounding Blackwater are heavy, the geese often resort to feeding at night when the moon is full, returning to the refuge and its marshes during the day. This explains why there are days when there appear to be no geese here; during these periods, sizable goose flocks are usually only seen at dawn and dusk.

Physical Characteristics

The color patterns of a Canada goose are so distinctive that it is almost impossible to confuse it with any other species. The head, bill, neck, feet, and tail are black, while the cheek patches, which meet under the white chin, are its most easily recognized characteristic. The upper parts are grayish-brown, with the underparts lighter and becoming white near the tail.

It is not easy to distinguish a gander (male) from a goose (female). Generally the gander is acknowledged as the larger of the pair, and he has a deeper sounding call.

At Blackwater, the average Canada goose weighs about 8 pounds, but their weights may range from a small 6 pounds to over 15 pounds for an older bird. The wingspread varies from 5 to 6 feet.

Canada geese held in captivity often live 20-40 years, but the geese who migrate to Blackwater probably live an average of 5 to 10 years.

Nesting and Family Life

Geese form very strong, lasting social bonds. A pair usually mates for life, although when one dies, the other remates. Some Canada geese nest for the first time at the end of their third year. They usually lay 5-8 eggs requiring about 28 days of incubation. The proud parents are very protective of their young goslings. Family ties remain strong throughout the first year.

While most Canada geese go north to nest, some resident geese remain at Blackwater where the young broods may be seen in early summer. This flock of resident Canada geese began with injured adults who could not migrate and stayed to raise their families at Blackwater. However, the resident geese have multiplied and become pests that often destroy crops planted for the migratory waterfowl.

Migrating Canada geese. Credit: Bob Quinn


There has been much speculation as to what causes the geese to begin their spring and fall migrations. The increasing or decreasing length of days, combined with weather conditions and other variables, motivate the geese to migrate twice yearly. Fat deposits accumulate just prior to migration and provide energy for the long flight.

The usual "V" formation provides each goose (except the leader) with favorable air currents in which to fly. Older geese alternately share the lead position. Geese have been observed at altitudes of 29,000 feet, although the normal migration altitude is only 3,000 feet.


Most of the Canada geese wintering at Blackwater NWR and other areas of the Eastern Shore travel north in the spring. The flocks begin moving out in late February and most are gone by mid-March. From here they travel to their ancestral nesting grounds on the Ungava Peninsula near James Bay, Canada. There, during the summer months, they nest and rear the young -- only to begin the cycle once again with their return to southern wintering grounds in the autumn.

Resident Canada Geese FAQ

  1. What are resident Canada Geese?

    Resident Canada geese refer primarily to local breeding Canada geese that nest and raise their young in Maryland, and more specific to this discussion, in southern Dorchester County. Resident Canada geese do not migrate to northern Canada, but remain in southern Dorchester County year-round. The geese became established on Blackwater Refuge from released captive and injured birds.

    Resident Canada geese are rapidly increasing in numbers throughout the Northeast region and are creating significant management problems in the entire area.

  2. How many resident Canada Geese are here on the Refuge?

    These semi-domesticated geese reproduced well; in fact, too well. The population has risen from 350 in 1989 to more than 5,000. Despite efforts to discourage the resident geese, they are reproducing at the rate of at least 2,000 new birds a year. The population is expected to continue to increase.

  3. How do the resident Canada Geese damage the Refuge?

    The primary damage is caused when too many geese continually feed in the same areas. They are so voracious, eating both newly-planted crops and marsh plants, that they literally strip areas barren of all plants. Approximately 40% of the Refuge's corn fields were recently lost to goose depredation. Newly planted ladino clover fields along the Key Wallace Road corridor have been heavily damaged. Moist soil vegetation in the Refuge's impoundments are heavily browsed. Regenerating marsh vegetation around the Wildlife Drive, already damaged by nutria and snow geese, has been damaged significantly.

    These areas provide critical forage for the Refuge's migrating and wintering waterfowl. In the past several years, it has become apparent that these areas are becoming so badly damaged, the Refuge doesn't have enough wintering habitat to support its 35,000 migratory Canada geese, 7,500 snow geese, 1,500 tundra swans, and 25,000 dabbling ducks. These resident geese are creating a situation where the refuge cannot achieve the purpose for which it was established.

    In addition, their fecal droppings concentrate in pools of water created during impoundment drawdowns, and thereby degrade overall water quality and increase the potential for human and avian diseases transmitted by fecal material. Droppings on the driveways and parking areas near and around the Visitor Center can become so concentrated as to create a safety hazard for walking.

    It is important to note that the Refuge is not the only area experiencing this damage. Several other property owners are also reporting damage of crops and marshlands due to resident Canada geese.

  4. What is the Refuge now proposing to do to manage resident Canada Geese?

    Under the proposed Integrated Wildlife Damage Management (IWDM) program, lethal and non-lethal methods will be used to manage the adult resident Canada goose population. It is important to remember that IWDM would involve a combination of techniques, including: (1) altering habitat; (2) fencing; (3) use of frightening/harassing techniques; and (4) population reduction through lethal control methods. The Refuge staff would tailor methods to meet the overall objective of reducing and maintaining the Refuge resident Canada goose population to the 1989 level.

    Lethal control has become necessary as the Refuge has conducted non-lethal methods for several years without success to control resident geese populations. Resident gosling production on the Refuge in 1998 and again in 1999 exceeded 2,000, despite the expenditure of at least one full staff year of effort and thousands of dollars for harassment/scare devices each year. These harassment/scare devices include: the use of propane cannons, balloons, flags, shell crackers, etc. None of these devices, or combinations of devices, prevent resident Canada geese from entering these areas.

    When necessary, Refuge staff would also live-trap resident geese, and transport them to a certified processor. In accordance with Maryland DNR's policy, the processor would euthanize the geese, and the meat would be donated to a charitable organization for human consumption. These control methods would be timed to avoid conflicts with returning wild flocks of migratory Canada geese.

  5. When would live-trapping occur?

    If the Service adopts the IWDM program, the live-trapping would occur sometime prior to the arrival of wild flocks of migratory Canada geese. Live-trapping will be most effective during a limited number of weeks when the resident Canada geese are in full molt and therefore cannot fly.

  6. What is the anticipated success of trapping?

    Trapping success is really up to the behavior of the resident Canada geese. Refuge staff will assess, on a daily basis, the behavior and movement of birds and determine whether or not trapping will be effective. Further, humane treatment of any captured birds requires that all features of the operation must be in place (from equipment to processor) prior to beginning a trapping effort. Refuge staff hopes that the trapping will remove enough resident Canada geese so as to see immediate relief of the croplands and marshlands currently experiencing the heaviest overgrazing.

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Last updated: September 30, 2010