The city goose and the country goose -- a tale of two changing habitats
This article first appeared in the St. Louis Beacon, March 16, 2010 - This is a tale of the city goose and the country goose.
Many of us become aware of the city goose as we begin to enjoy the spring in our favorite local parks. The city goose -- aka the Canada goose -- has become a nuisance in many urban green spaces.
The country goose -- aka the snow goose -- minds his own business. For us, these geese are mostly out of sight and out of mind as they pass through in the late winter and early spring. But they have become a threat to the Arctic environment where they hatch their goslings.
Geese on 'spring break'
Each summer, around the solstice, geese lose their flight feathers and cannot fly for about a month. At the end of this molt period, parents and children have new flight feathers. The goslings imprint upon the area where they learn to fly and return to that area when they are ready to establish their own nests.
But the geese don't usually reproduce until they are 3-4 years old.
During the summers of their adolescence, the 1- and 2-year-old giant Canada geese go on a "molt-migration." They fly to the Hudson Bay and join all the migrating geese for that one summer molt. In the fall, they fly south, where they settle down and begin to raise their families. Normally, they migrate only short distances for the rest of their lives.
Canada geese, like other geese, are monogamous. With their life-long mates, they incubate five to seven eggs each breeding season and stay with the goslings for their first year.
Let's start with the city goose. In the winter, a visitor to Forest Park may see a few hundred Canada geese. Most will be gone by the spring, as they migrate north. But a subspecies native to the state, the resident giant Canada goose remains here through the winter, beginning its nesting preparations.
Nesting starts in mid-March and peaks in mid-April. During this time, the male goose becomes aggressive toward humans as he protects his mate while she sits on the nest and takes care of the newly hatched goslings. An adult giant Canada goose can weigh up to 16 pounds, so if one confronts you hissing and honking, give him a wide berth.
Erin Shank, urban wildlife biologist with the Missouri Conservation department, says the department fields hundreds of phone complaints every April about aggressive geese.
As recently as the 1960s, the giant Canada goose was thought to be extinct. When several small populations were discovered, wildlife agencies worked to protect these North American natives. Their success has been spectacular. Naturalists estimate that the population of these former wetland dwellers has reached about 3.5 million nationally; 50,000-70,000 live in Missouri.
What caused this population explosion? Canada geese share an aesthetic with humans. Their preferred habitat is a pond or lake surrounded with grass mowed down to the water's edge, giving them clear sight of predators like foxes and raccoons. Such a manicured environment is found in urban parks, subdivisions and office parks. The geese are even happier if a fountain is part of the lake or pond because the aeration keeps the water from freezing in cold weather.
As swamps and wetlands gave way to subdivisions and office parks, giant Canada geese moved right in to safer surroundings. They don't mind being around people, especially if the people feed them. Of course, as they exploit the kindness of strangers, their droppings make a mess of the lawns and they are apt to overgraze the area.
But on the whole, city dwellers and city geese have adapted to one another. And while their numbers increased exponentially during the 1990s, the census in Missouri seems to have stabilized over the past 10 years, according to Andrew Raedeke, Missouri waterfowl resource scientist.
The Country Goose
The snow goose has also experienced a population explosion during the last 40 years, after a decline in the early 1900s.
While the Canada goose is in your face, you usually need to seek out the snow goose. These country geese will visit for days or weeks, roosting in groups of thousands on large bodies of water such as "Swan Lake" in the Two Rivers National Wildlife Refuge near the confluence of the Mississippi and Illinois rivers. During the first week in March, one wildlife refuge in central Missouri hosted more than 1 million of these travelers.
Snow geese require open water and grain fields. As Ken Dalrymple of Illinois' Two Rivers puts it, the geese use crowd psychology, massing together at night on the deepest part of the water, and then scavenging for waste grain en masse morning and evening. With this lifestyle, they have few successful predators. They will stay in an area until the food is exhausted, or until snow comes.
Snow geese nest in the salt marshes of the Arctic tundra, arriving in April and early May. They hatch the goslings in the short summer and begin the long migration as far south as Mexico in September. They are outstanding flyers. They fly at high altitudes -- from 1,000 to 10,000 feet in noisy groups at speeds of about 50 miles an hour. They fly at night as well as during the day, and if necessary can go 1,700 miles in one flight. However, most stop along the way at wildlife refuges for days or weeks. As they return to nesting grounds during the three-month spring migration, they feast during their travels, gaining up to two pounds a bird.
The snow goose population explosion is resulting in the destruction of the Artic tundra where they nest. There are simply too many birds eating the vegetation that bursts out during the short summer. Considering that a newly hatched gosling weighs just 2.5 ounces but grows to about 5 pounds in 90 days, it is easy to see that 4.5 million nesting birds could easily denude their home.
Naturalists have no simple explanation for the population explosion. A leading hypothesis is that the coastal marshes where they used to feed on aquatic plants during the winter have been greatly reduced and replaced with rice farms that can feed a bird very well. With ample, nutritious food, more birds may survive to the next nesting season. And mating pairs, which lay eggs every year for up to 20 years, only need four progeny to survive to double the population.
Wildlife management measures to reduce the number of snow goose have mainly consisted of expanding the hunting seasons and limits. Naturalists worry about mass starvation or disease outbreaks that could destroy other bird populations. They also worry that the tundra may never recover from overgrazing.
The planet changes constantly. A new fashion in landscape design has an impact on the population of one species of goose. And in the case of another species, a change in feeding patterns may lead to the destruction of a habitat thousands of miles away.
Jo Seltzer is a freelance writer with more than 30 years on the research faculty at the Washington University School of Medicine and seven years teaching tech writing at WU's engineering school.