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Wildlife and forestry research
Learn about wildlife and forestry research
Wisconsin Bear Hunters Association members volunteer to set baits.

Wisconsin Bear Hunters Association members volunteer to set baits.

Bait box containing tetracycline laced bait.

Bait box containing tetracycline laced bait.

Claw marks allow us to determine which species consumed the bait.

Claw marks allow us to determine which species consumed the bait.

Black bear bone tissue positive for tetracycline. (Courtesy of MN DNR)

Black bear bone tissue positive for tetracycline. (Courtesy of MN DNR)

Wildlife and Forestry Research - Black Bear Research Projects

Background

Black bears are Wisconsin's largest carnivore. Their population has grown and expanded over the last 30 years. Bears are a significant member of Wisconsin's native ecosystems. They are also an important species for our state's tribes and provide exciting wildlife viewing and hunting opportunities for residents and visitors. Bears can also cause nuisance problems at homes and farms. Proper management of this species requires high quality data on their population and behaviors. The DNR invested in 2 research projects to answer questions about our state's bear population size and their foraging ecology.

Black bear population estimate

Our goal was state-wide and bear management unit specific black bear population estimates. We used a biomarker based capture-recapture estimator. Capture-recapture studies have two parts. The first involved marking a subset of the population in some fashion. In this study, bears were "marked" when they ate baits embedded with tetracycline. Tetracycline is a common antibiotic which leaves a detectable mark in bone tissue. In the spring of 2011, DNR staff and over 600 volunteers from around the state set and checked 3,361 tetracycline laced baits in 33 counties.

The second part of the study involved recapturing a subset of the population. For this study, the recapture took advantage of the 2011 and 2012 bear hunting seasons. Successful bear hunters were required to submit both a rib and a tooth sample. Ribs were analyzed for tetracycline exposure and teeth were used to determine the year of exposure.

Our population estimate relied on three pieces of information: the number of bears that ate tetracycline baits, the number of bears harvested, and the number of harvested bears marked with tetracycline in their bone tissue. These data were incorporated into capture-recapture models to estimate bear population size.

Currently, teeth are the only samples that are collected from harvested bears. The teeth are sent to a lab where they are analyzed and aged. This age data helps give us an idea about the age structure of our population estimates.

Project timeline: Spring 2011- Fall 2013

Lead DNR scientists: David MacFarland

Black bear foraging ecology and telomeric aging

Little information is available on black bear foraging ecology in Wisconsin. The composition of black bear diets likely varies dependent on local ecosystem characteristics, seasonal changes in food availability, and availability of human sourced food. Our research will take advantage of recent advances in stable isotope analysis to evaluate the composition of bear diets within a study area in North Central Wisconsin. Various bear tissue samples will be collected at registration stations and analyzed against known isotopic signatures of potential bear foods. The different tissues give an indication of diet over different periods allowing for analysis of changes in diet through time. This information will provide a better understanding of the ecology of bears in Wisconsin. A second component of this project aims to develop a technique for aging bears through DNA. Telomeres are a component of DNA which degrades as an animal ages. We will use known age tissue samples to quantify the rate of telomeric decay in black bears. This will provide a non-invasive bear aging tool.

Project timeline: 2011 - 2016

Lead DNR scientists: David MacFarland

Partners


Wisconsin Bear Hunters Association

Wisconsin Bear Hunters Association

DNR Bureau of Wildlife Management

DNR Bureau of Wildlife Management

University of Wisconsin

University of Wisconsin

Colorado Division of Wildlife

Colorado Division of Wildlife


Get Involved

Our bear research relies upon hunter submitted biological samples. If you are a bear hunter you can help by submitting a tooth from your bear.

Our population research uses hunter submitted tooth samples. All successful hunters are required to submit a tooth from their bear. Guidance on how to submit your tooth sample can be found here.

Our bear diet and aging research is being conducted in North Central Wisconsin. Participation in this research is voluntary. Those who volunteer to submit samples will receive a report on the diet and nutritional condition of their bear. At this time we are only requesting samples from successful hunters in Deer Management Units 6, 13, 14 and 28 (http://dnr.wi.gov/topic/hunt/documents/dmu.pdf). Interested hunters can contact Becky Kirby (608-890-3430) for more information and details on how to participate.

Contact Us

For more information about black bear research, please contact:

Maggie Stewart
Assistant Big Game Ecologist
608-261-7588

Last revised: Tuesday September 05 2017