Population Research is Basis of Species Management

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Sustainable management of Wisconsin’s game and nongame birds and mammals depends on accurate population counts, harvest numbers and sound scientific data. The Department of Natural Resources annually conducts more than 60 population surveys to determine safe species harvest levels and population distributions. These efforts are paid for in large part by hunting license fees.

“Sound harvest management requires basic knowledge of the population dynamics of a species,” said Gerry Bartelt, chief of wildlife and forestry research at DNR. “Knowing overall population size and distribution of that population on the land and reproductive success are absolutely essential to setting safe harvest limits for game animals. The same information is vital for management of nongame species such as wolf, elk, prairie chicken, eagle and osprey and Wisconsin’s 11 species of frogs and toads.”

Hunter information is also collected and added to the mix in setting harvest limits, Bartelt says. Surveys are mailed to a random selection of hunters and trappers asking about things like overall satisfaction, hunting or trapping techniques used, days spent afield, attitude toward proposed changes to seasons and management, and areas hunted or trapped.

Researchers enlist help from field staff and the public in gathering population data. Much of the annual information is submitted by license fee supported wildlife and fisheries field biologists and conservation wardens. The history of wildlife survey work for scientific management of populations dates back to 1931 with the publishing of Aldo Leopold’s text, “Game Surveys of the North Central States.”

Wildlife research is also used in the courts on occasion. The Department of Natural Resources was sued to list the bobcat as a state threatened species in the early 1990s. The case made it all the way to the State Supreme Court. The Court, after studying bobcat population data collected over a period of more than 20 years, decided that there was no basis for listing the bobcat. Today, the popularity of hunting or trapping this elusive predator means a four- to five-year wait to earn one of the limited number of harvest permits.

Hunters and trappers must register every bobcat harvested. This data along with information on age, sex and reproductive rates is used to closely monitor and adjust harvest limits as necessary. Other popular species also must be registered including deer, bear, turkey, otter, fisher and exterior zone Canada geese.

“Population information becomes more valuable with time,” says Bartelt. “We’ve collected data on some species annually for almost 40 years. It’s this kind of long-term population study that is most valuable in spotting trends or heading off potential problems. If funding for these efforts is lost and survey frequency is spread out or dropped, our confidence in interpreting the data also drops.”