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Wisconsin has a rich diversity of natural resources. Some of our natural heritage, however, has been lost forever. In many cases, we neither note the occasion, nor know when a species becomes extirpated.
This was not the case with the passenger pigeon.
The last passenger pigeon was shot in Babcock when the state had barely turned 50 years old. On May 11, 1947, the Wisconsin Society for Ornithology (WSO) commemorated that loss with a plaque that resides on a high ridge at Wyalusing State Park overlooking the Mississippi River Valley, where flocks of innumerable migrating passenger pigeons once filled the skies. Aldo Leopold, present for the dedication, captured the regret at losing the passenger pigeon and expressed hope to prevent similar, future tragedies in his essay, "On a Monument to the Pigeon," in A Sand County Almanac.
Today, we think Leopold would be pleased with the progress we are making in managing threatened and endangered species; in designating, managing, and restoring State Natural Areas; and in broadening our knowledge of plant and animal communities. In some cases, such as with the trumpeter swan and peregrine falcon, what was once lost is now being restored.
Here are the stories of two other species, now fully recovered from near extirpation in the region.
Double-crested cormorants historically occupied large, isolated lakes and wetlands in northern Wisconsin. There were no documented breeding colonies in the state until about 1920, when cormorants were reported nesting on Lake Wisconsin in south central Wisconsin. From the 1920s to 1950s, cormorants occupied 17 colony sites in 16 counties along the Wisconsin, St. Croix and Mississippi rivers.
The total number of nesting pairs statewide reached at least several hundred in peak years.
Beginning in the 1950s, three factors contributed to a population decline: habitat loss due to tree thinning and blowdowns, reproductive failures due to the effects of DDT, and human raids on islands off the Door County peninsula to destroy nests, eggs and young .(Cormorants were viewed as competitors for fish.) By 1966, only 30 nesting pairs survived in the state, and in 1972, the bird was listed as state endangered.
In 1974, UW-Stevens Point in cooperation with the Department of Natural Resources started building cormorant nesting platforms. The artificial nests erected on phone poles were designed by then UW graduate student, today DNR wildlife manager, Thomas Meier. Platforms were first installed at 13 locations from the Cat Island chain in lower Green Bay to Crex Meadows in the northwest to the Trempealeau National Wildlife Refuge on the Mississippi River. The platforms declining levels of DDE (formed as DDT is ingested) in their diet and protection as a state-endangered species, led to a notable recovery. Cormorants were taken off the state endangered species list when the population reached nearly 3,000 nests in 1986. Another important factor in the resurgence: cormorants fed heavily on Lake Michigan alewives. As cormorant populations began to recover in the 1970s, the alewife was highly abundant and easily taken.
By 1997, the state's cormorant breeding population had grown dramatically to over 10,000 nests at 23 colony sites. Still, more than 80 percent of these nests are concentrated on four Green Bay/Lake Michigan islands, raising concerns among some that large numbers of these birds are again viewed as competing with commercial and sport fisheries on the lake. For now, many celebrate that the double-crested cormorant is indeed back!
Timber wolves are the largest wild members of the dog family. Before Europeans settled North America, wolves roamed areas from the southern swamps to the northern tundra. They existed wherever there was an adequate food supply. Then, wolf habitat was slowly transformed into farms and towns. As the continent was settled, wolves declined in numbers and became more restricted in range.
Explorers, trappers and settlers transformed native habitat into farmland, hunted elk and bison to extirpation, and reduced deer populations. As their prey species declined, wolves began to feed on easy-to-capture livestock. As might be expected, this was unpopular among farmers. In response, the Wisconsin Legislature passed a state bounty in 1865, offering $5 for every wolf killed. By 1948, at Wisconsin's centennial, wolves were disappearing; about 50 remained in the state. The bounty on wolves continued until 1957. By 1960, the wolves were gone.
In the mid-1970s timber wolves were more valued and protected under the federal Endangered Species Act of 1973. With protection, Minnesota's wolf population increased and several individuals dispersed into northern Wisconsin. In 1975 the wolves were listed as endangered in Wisconsin, and a wolf study program began in 1979. The state wolf population grew slowly: in 1985, only 15 wolves occurred in the state. A Wolf Recovery Program developed in the 1980s set a goal of maintaining 80 wolves for three years before the species would be reclassified as "threatened." By 1985, eighty-six wolves lived in the state; by 1997, the population had increased to 150 wolves. During the sesquicentennial year of 1998, Wisconsin's wolves may need less protection and will be upgraded from "endangered" to "threatened." Work is underway to develop a plan to manage the 300-500 wolves ecologists believe the state can sustain. The wolf is again part of Wisconsin's landscape.
Sumner Matteson is an avian ecologist, Adrian Wydeven, a mammalian ecologist, and Barbara Zellmer is chief of the Ecosystem & Diversity Conservation Section for DNR's Bureau of Endangered Resources.