Winter 2000

[TEXT ARCHIVE WEB-PUBLISHED MARCH 2002.
ORIGINAL PRINT PUBLICATION DATE: WINTER 2000.]

The Mingled Destinies of Beavers and People

By Jack MacRae

I trust beavers need no introduction. They are big, brown, bucktoothed rodents that chew down trees and construct dams. They have been sharing the land and waters of the Chicago Wilderness for the last 10,000 years or so with the human species. For a short period in the 17th and 18th centuries, their relative importance rose considerably when the fashion of the day dictated that ladies and gentlemen could only be properly dressed if they wore a felt hat, manufactured from the pressed fur of the beaver. The demand for beaver pelts was so great that, by the end of the 19th century, the beavers had been trapped out, essentially extirpated from Illinois.

For most of the 20th century, beavers were missing from the biodiversity of our region. People interested in seeing local beavers would have to be satisfied with captive beavers in zoos or with mounted specimens in museums. That is, until a 1950s project to reintroduce the beavers was initiated by the Forest Preserve District of Cook County. (Earlier attempts to establish colonies of beavers had been successful elsewhere. The Fish and Wildlife Service had released several pairs of beaver into Jo Daviess County in the 1920s and 1930s.)

As rodents are wont to do, the Cook County beavers reproduced rapidly. Within 20 years, beavers found their way across the Chicago Wilderness. The Des Plaines River, the Fox River, the DuPage River, and their many tributaries all became home to thousands of beavers. The wildlife that depends on beaver ponds had a great resurgence. Lovers of wildlife were thrilled that this appealing animal had been restored. Thrilled, that is, until the beavers started to disperse into, ahem, certain sensitive areas.

To wit: On the southside of Chicago, in the historic Jackson Park Lagoon is the Paul Douglas Nature Sanctuary, affectionately known as Wooded Island. It is one of the premier sites in Chicago for birding; dozens of species can be spotted in a relatively short time. This island is also home to a small colony of beavers, who until recently have maintained a fairly benign presence. But lately, the beavers have been taking more than their fair share: 75 large trees have been gnawed down, causing consternation among the birding crowd. The solution? Chain link fence has been wrapped around 60 or so trees, and on the advice of the US Fish and Wildlife Service, several hundred trees have been painted with a sand-impregnated varnish to deter chewing.

In Lake Calumet, within the "Big Marsh," a rookery of black-crowned night herons has been established in a large stand of common reed. These state-endangered birds nest communally, typically in trees, but in this instance their nests were located amongst the emergent vegetation. During the winter of 1998-99, however, a drainage culvert became plugged, disrupting the outflow of water, thus flooding the stand of common reed, effectively forcing the herons to search for new living quarters. The Chicago Department of Environment, with the help of various agencies, removed 30 truckloads of debris. The water receded for a while, then stopped. The reason? Beavers had dammed up the open culvert. This began a battle between city workers tearing up the dams, and the beavers rebuilding them. Fortunately for the herons, the common reed has regenerated and is expected to provide good nesting habitat for the year 2000 nesting season — weather, and beaver, permitting.

Poplar Creek is a little, meandering, spring-fed creek in the northwest corner of Cook County. The flowing waters provide excellent habitat for such uncommon fish species as the fantail darter and rainbow darter. It's also home to a colony of beavers who are doing their best to dam the creek to create a beaver pond. The problem is, a beaver pond would ruin the darters' spawning grounds, as slower moving water would allow silt to cover the gravel bed. Thus, in order to protect certain species, the beaver dams are removed on a regular basis, allowing the creek dwelling fish to procreate their species.

In DuPage County's Fullerton Park, resident beavers had created a pond through their damming activities. Shortly thereafter, the shore of this pond sprung to life with numerous wetland and wet prairie plants, as the buckthorn and box elder thickets became drowned out. The volunteer site steward recalls a huge increase in shore birds visiting the preserve. Unfortunately, the pond also affected an adjacent field, earmarked for future development. So, a device referred to as a beaver pipe was installed and the wetlands were effectively drained.

Along the border between Indiana and Illinois, vigilant members of the local Audubon Society alerted authorities to beaver activity at Wolf Lake. It seems beavers were gnawing into trees found growing along the slag banks of the lake. Birders were concerned that these trees, if lost to the beavers, could not be replaced, due to the current conditions of the shoreline. The authorities, however, told the birders (and the press) they planned to do nothing about the beavers, saying they were reluctant to raise the ire of the animal rights activists.

Lastly, one day several years ago, an Evanston firefighter named Jim arrived for his scheduled shift at the Central Street Fire Station #3 next to the North Shore channel. He parked his pride and joy, a shiny Volvo station wagon, in a seemingly safe parking spot. Unbeknownst to Firefighter Jim, the trees he parked under had been targeted by a hungry beaver. I'm sure you can guess what happened. No word on the insurance claim.

Of course beavers have a profound impact on their surroundings; they always have! But beaver activity cannot be labeled as good or bad, it's just who they are. While studies show plant diversity increases through their feeding habits, beavers have, in isolated areas, removed every tree in a park. The occasional flooding caused by beaver activity assists in a natural and important disruption in hydrology. In short, beaver activity helps some species, and hurts others.

In this day and age, the proverbial collision between nature and people is commonplace. Should beavers, like whitetail deer and cherry trees, be controlled when they threaten other species? One must remember, controlling beavers, like nearly all aspects of natural area management, is not achieved through a vaccine. It is not something that can be applied once and then never again.

Blaming beavers for flooding, loss of suitable bird habitat, and siltation of our waterways is wrong headed and stupid. Human development of our landscape is a far greater threat to the natural areas and systems than any rodent. In a natural setting, with natural processes in place, beavers are merely another interesting addition to a region's fauna. But, in a highly artificial landscape such as ours, with only fragmented islands of nature remaining, beavers can spell trouble for certain plants, animals and, of course, firefighters.