Leon M. Lederman
Science Education Center
Fermilab Flora and Fauna Vitrual Exhibit
Canada Geese
What are Canada geese?
The Canada goose (Branta canadensis) is a large waterfowl common at Fermilab. It is easily identified as a large, plump bird with a long black neck, white chin strap, buff and brown body, and black legs. It is the most common and best known goose in North America. The males and females look alike with the males being somewhat larger. These powerful long distance flyers range over the entire North American continent when migrating.
Why are the geese attracted to Fermilab?
The cooling ponds (which are
used to cool the magnets in the accelerator) at Fermilab are less
likely to freeze in the winter making it a desirable habitat for
waterfowl, especially geese. In recent years the ponds here at
Fermilab have attracted a migratory and resident population. About
26,000 geese can be found here during the semi-annual migrations
and winter season. In less severe weather they disperse to the
various retention ponds and waterways of the area.
What do they eat?
A casual observer will often see the flocks grazing in the grass. A mowed lawn around a pond has fresh grass shoots and a wide area of visibility for the eating flock. It is easy to see sentinels posted amongst the eating geese. There are always a few with their heads up, keeping watch. Along with grass, geese eat aquatic plants and even small water animals like snails. During spring and summer they eat grasshoppers, other insects, and earthworms. With the advent of farming, geese added domestic grains to their diets and now are frequently seen gleaning corn in harvested fields. Geese are among the few kinds of birds that can live on a diet of grass. Their legs are placed farther forward on their bodies than those of ducks and swans as an adaptation to grazing. However, they digest grass poorly and it passes through their bodies in about two hours. For this reason, geese must eat a lot of grass and therefore graze almost constantly.
Why are there so many Canada geese here year round?
Our year round population consists mostly of the giant subspecies (Branta canadensis maxima) which does not migrate like many of the smaller subspecies. They need an open water spot and source of food. Fermilab's cooling ponds, groomed lawns, surrounding farms which grow grain, and lack of predators, make a good home for these geese.
Why do some of the geese have collars?
Several years ago Fermilab was designated the sixth National Environmental Research Park within the Department of Energy. It allows the Illinois Department of Natural Resources to catch and band geese at Fermilab. Nape (neck) collars are found on some of the older geese, but leg banding is now the preferred method. Like all birds, Canada geese molt their flight feathers once a year. This happens all at once during nesting in June. The adult birds are rendered nearly flightless, so it is easier to catch them. Usually the DNR bands about 25-50 birds every year. They weigh and measure the birds, determine their gender and subspecies, and gather the data that is useful to study the Fermilab and surrounding populations.
What are the nesting
habits of the Canada goose?
A female Canada goose will normally lay between 4-8 eggs in a nest most often built on the ground near a pond. The mother hollows out a spot with her body, reaches out to gather vegetation from the surrounding area to build up a nest wall, and lines the bottom with down. She sits on (incubates) the eggs with the gander standing watch. The goslings hatch in about 28 days. Unlike many other birds, goslings are not fed by their parents. They are able to leave the nest and graze, walk, and swim within a few hours after hatching. They are then tended by both parents. It is common here at Fermilab to come across the mother followed by five or six goslings and the gander bringing up the rear!
