In the last ten years, the population of Canada geese
permanently residing in suburban America has skyrocketed.
These are full-time residents who don't fly away with the
first ice. They are big and intimidating, hissing and
charging in defense of their territory. There are so many of them that their ordinary honking can even become irritating.
They eat turfgrasses down to a nub and then leave
uncountable piles of slimy green droppings to be stepped in.
And, they can spread disease. Almost overnight, these
once-endangered birds have become pests at some Illinois lakes.
The suburban landscape contains food and space to support a few geese without causing too much difficulty for people.
Giant Canada geese, however, like to stay around where
they are hatched, in the same way that migrating geese tend to return to the same spots year after year. The lack of predators and abundance of food allows giant Canada geese to lay more eggs and have more goslings survive to adulthood than would be normal in the wild, so a small population can quickly grow into a large population. In addition, the presence of geese and goslings (as well as ducks) is an attractant to other giant Canada geese who might have been displaced from another area.
In addition to the trouble they cause for people living
around lakes, excessive, unnatural populations of giant
Canada geese are as much or more of a problem for the
lakes themselves. Geese eat plant material on land, but are frequently out on the water or ice when they defecate. This material is high in nutrients derived from the plants they eat.
These nutrients are the same ones used for growth by algae and plants in the lake. When the geese become year-round residents, the nutrient loading can become very significant, contributing to algal blooms and excessive plant growth. In fact, one Canada goose can contribute about a half pound of phosphorus to the lake each year. If you have 20 resident geese on your lake, that is the same as dumping a 100- pound bag of fertilizer with a "10" phosphorus number into the lake each year!