Canada's namesake bird, the Canada goose, has become a major pest south of the border and some states are killing the geese in an effort to control the population boom.

The geese create a mess in parks and fields, littering the grass with droppings. They sometimes also attack people, becoming territorial of areas in which they breed and feed.

Between October 2005 and September 2006, about 13,160 resident Canada geese were killed in the United States by the U.S. Department of Agriculture's Wild Life Service. Most of them were culled in eastern states like New Jersey, New York, Wisconsin and Pennsylvania.

'Resident' Canada geese nest in the U.S. and southern parts of Canada. They're one of several kinds of Canada geese, and their numbers have been booming in recent years.

Retired University of Toronto professor Theo Hofmann has studied bird populations and says humans are partly to blame for the population explosion of Canada geese.

Years ago the geese would have naturally flown to vast fields in the southern United States for food during the winter months, he said. But a warmer climate and the continued feeding of geese by people has kept the birds closer to home.

"One of the major problems is that people have been feeding them. That's certainly what started it... as long as there getting fed and they find food they don't feel the need to migrate," Hoffman told CTV.ca.

"In the last 60 years they've rapidly increased in numbers and they're very successful in breeding. They have five, six, seven young and they have no enemies so no animals kill them and so they're spreading wildly."

Typically, the geese are protected under The Migratory Birds Convention, a shared treaty between Canada and the United States.

The rules of a cull

But provisions in the treaty recognize the overpopulation of geese can cause problems for humans and other birds. It allows the killing of Canada geese as a "last resort, to be undertaken only after other attempts to deal with the problem have been tried and failed," Environment Canada told CTV.ca in a statement released Friday.

"A Canada goose could not be captured, harassed, shot, wounded, killed or collected with out a permit," Carol Bannerman, a spokeswoman from the U.S. Department of Agriculture's Wildlife Service told CTV.ca.

Permits are issued by the U.S. Department of the Interior. To get one, Bannerman says evidence must be shown that the geese have caused damage and that non-lethal methods of population control have failed.

"Basically what is being sought is not to remove all resident Canada geese -- that's not the idea. The idea is to establish a population that is healthy ... that there is sort of a peaceful coexistence between wild life and humans," Bannerman said.

Some non-lethal methods of controlling the Canada geese population include:

• Covering geese eggs with oil to prevent hatching,
• Habitat modification to discourage the geese from staying in a particular area,
• Using pyrotechnics to scare the geese.

Bannerman said sometimes those efforts only temporarily remove the geese, "or move one area's problem to another area."

New Jersey has the highest concentration of resident Canada geese, as well as the highest density of people, a combination that's created a lot of conflict between humans and the birds, Bannerman said.

In 1990 the Garden State had 28,000 resident Canada geese. By 1999, the population had ballooned to 82,000.

This summer the town of Montclair, New Jersey hired a private company to take care of its overpopulation problem.

In June, about 80 Canada geese were rounded up from local parks and shipped to a facility in the state where they were electrocuted and processed for food.

The meat was donated to local food banks, but was rejected over concerns it could contain environmental toxins. The decision to kill the geese also sparked protest from some residents and local animal rights groups, who felt non-lethal methods of population control had not been exhausted.

U.S. residents have also complained to Environment Canada about actions taken in their country to manage local populations of Canada geese. Environment Canada said those complaints are redirected to the U.S. Department of the Interior.