Hungry Bears

Mark Ditmer holding a black bear cub

Mark Ditmer holding a black bear cub

If I asked you to name three favorite foods of bears, you would probably list off honey, berries, and salmon. But did you know that some bears also like corn and even sunflower seeds? Mark Ditmer, the Consbio program’s most recent grad, has spent the last several years studying what black bears eat in the far extreme of the Eastern black bear population’s range. His work attempts to explain how bears are managing to succeed in Northwestern Minnesota, an area previously thought to represent marginal habitat, but that is now the only part of Minnesota with an increasing bear population.

In order to survive a winter’s hibernation, bears need to pack on the pounds during the fall. Ditmer found that captive bears, given a choice, were basing their food intake on which items had the highest caloric content: fatty oil sunflower seeds were preferred over corn, acorns, and lower-calorie convection sunflower seeds. His stable isotope analysis of wild bears similarly showed that while corn and sunflowers made up a relatively small proportion of the available landscape, they were accounting for a disproportionately large amount of the diet.

As it turns out, crop fields provide easy foraging. By utilizing heart rate biologgers developed by Medtronic, Inc. and GPS-collars, Ditmer found that whereas when bears move across areas of open agricultural lands (without crops that bears prefer to eat) they exhibit faster movement and heart rates, their movement will actually decrease, and so may their heart rates, when they are foraging in crop fields. What could be easier than sitting in the middle of a corn field, and munching on every ear within arm’s reach? Of course, this kind of behavior gets bears into trouble with farmers. The havoc caused by a bear eating corn is much more visible than when a deer wanders through a field taking a bite here and a bite there.

So to answer Ditmer’s question, (how are bears managing to thrive in the marginal habitat of Northwestern Minnesota?) it turns out, bears in Northwestern Minnesota have much larger home ranges than bears in other places. Typically large home ranges are associated with poor habitats but Ditmer’s findings suggest that the males’ roaming is used to seek out and then hone in on the best available forage. Bear home ranges expand and contract in the short-term as different food resources become available. For instance, bears tend to stick to a smaller area if they have ripe crops in their home range, but before the crops ripen they are using a much larger area. As a general rule of thumb, the higher the caloric density (the more food there is) the smaller the bear’s home range will be. Crop fields are particularly dense in calories, so bears, especially the bolder males, are likely to use crops to forage to prepare for a long winter without any food. However, female bears seem willing to reduce or avoid raiding crop fields if other options in natural habitat, such as an oak forest full of acorns, are available in a given year.


CB PhD Student Jennifer Biederman featured on the Fisheries Blog

Current student Jennifer Biederman was featured as a guest contributor on the Fisheries Blog. Her post explores the relationship among reading, gender and science – and touches on what it’s like to be a new mom in graduate school. Enjoy!

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Get to Know the New Cons Bio Cohort- 2013 Edition (Part 2)

Get to know more about the new UMN Conservation Biology students:


JoeyName:  Joey Lechelt
Hometown: Chanhassen, MN
Other colleges/universities attended (undergrad and/or graduate):  University of Wisconsin-Madison
Advisor:  Przemek Bajer
Degree anticipated:  MS Conservation Biology
Research interests: Common Carp Recruitment, including biocontrol mechanisms and movement
Favorite hobbies:  Fishing, watching sports, beach volleyball
Favorite thing that’s green:  Pine Trees
Last read: A Biography of the Fish that Changed the World
Favorite place on Earth: Glacier National Park
Guilty pleasure: Ice Cream


david-pavlikName:  David Pavlik
Hometown: Holt, MI
Other colleges/ universities attended (undergrad and/or graduate):  Northern Michigan University for undergrad
Advisor:  Rob Blair
Degree anticipated:  Master’s
Research interests: Butterflies and butterfly conservation, disturbance and nectar availability

Favorite hobbies:  Birding and Photography
Favorite place on Earth: Homer, Alaska
Guilty pleasure: Fantasy Hockey


Nathan_Banet_PhotoName:  Nate Banet
Hometown: Saint Louis, MO
Other colleges/universities attended (undergrad and/or graduate):  University of Portland
Advisor:  Peter Sorensen
Degree anticipated:  MSc
Research interests: Seabird and salmonid habitat conservation, saltmarsh habitat and avian research, invasive species control
Favorite hobbies:  backpacking, climbing, biking, skiing, traveling, running, anything outdoors
Favorite thing that’s green:  Pacific Northwest
Last read: The Last Flight of the Scarlet Macaw
Favorite place on Earth: Queensland, Australia
Guilty pleasure: Craft breweries

Get to Know the New Cons Bio Cohort- 2013 Edition (Part 1)

Get to know more about the new UMN Conservation Biology students:


Blog_BegaName:  Bega Inaho
Hometown: Eastern Highlands Province of Papua New Guinea
Other colleges/universities attended (undergrad and/or graduate):  University of Papua New Guinea
Advisor:  Dr. George Weiblen
Degree anticipated:  MSc
Research interests:  Forest Ecology, Plant Systematics and Conservation
Favorite hobbies:  Backyard gardening, watching movies and music
Favorite thing that’s green:  Trees
Last read:  Local Newspaper
Favorite place on Earth: Nothing’s better than Home
Guilty pleasure: Cigarettes


Blog Kathryn SwansonName:  Kathryn Swanson
Hometown: Spring Lake Park
Other colleges/universities attended (undergrad and/or graduate):  University of Minnesota (Ecology, Evolution and Behavior and Spanish/Portuguese) and La Universidad Católica de Valparaíso (Undergrad Exchange)
Advisor: Susan Galatowitsch
Degree anticipated:  PhD
Research interests:  Wetlands, hydrology and global climate change
Favorite hobbies:  Camping, biking, pottery, reading, photography
Favorite thing that’s green:  Rain gardens
Last read:  Finding Mañana: A Memoir of a Cuban Exodus, by Mirta Ojito
Favorite place on Earth:  Ilha do mel, Paraná, Brazil
Guilty pleasure: Corny ABC Family TV shows


Blog_RodrigoName:  Rodrigo Villalobos Aguirre
Hometown: Santiago, Chile
Other colleges/universities attended (undergrad and/or graduate): Veterinarian, Universidad de Chile
Advisor:  Ron Moen
Degree anticipated:  PhD
Research interests:  Mammals, carnivores, Wildlife Conflict
Favorite hobbies:  Travel, trekking, snorkeling
Favorite thing that’s green:  Older Trees
Last read:  Top of the World by Hans Ruesch
Favorite place on Earth: Chilean High Plateau, Chilean Rainforest, Ko rok Thai island
Guilty pleasure: Wine and beer


Blog_AaronName:  Aaron Claus
Hometown:  Rochester, MN
Other colleges/universities attended (undergrad and/or graduate):  University of Denver
Advisor:  Peter Sorensen
Degree anticipated:  M.Sc.
Research interests:  Fish behavioral manipulation, conservation biology, invasive species control.
Favorite hobbies:  Angling, Competitive Paintball, Soccer
Favorite thing that’s green:  A productive lake or river
Last read:  World War Z
Favorite place on Earth:  Rio Juruena, BR
Guilty pleasure:  JIF reduced fat peanut butter

Life and Boats

Editorial note: The following is a repost from by CB student Leif Devaney

Titanic_lifeboatIn an enormously influential article published in 1974 in Psychology Today, and in a longer version published later that year in BioScience, Garrett Hardin introduced the metaphor of the lifeboat for economic and ethical consideration. This conceptual construction was intended as an improvement over the then-popular ecological metaphor of “spaceship earth” coined by Kenneth Boulding in 1966. Interestingly, in the opening paragraph of “Living on a lifeboat”, Hardin indicates that metaphors in general may be understood as only an early stage in mentally approaching difficult problems, and that this stage may be surpassed as theory advances and becomes more rigorous.

In Hardin’s analogy, large entities such as nations or the biosphere are likened to a boat, while smaller entities – for example, migrating individuals or groups – are likened to swimmers trying to board the already cramped vessel and exploit whatever resources are on board. In the imagined scenario, it is believed that the boat is near carrying capacity, but exactly how near is not known with certainty given the many future possibilities. A central question focuses on at what point, if any, the risk of sinking the entire boat outweighs the good provided for each additional rescued swimmer.

The metaphor of the lifeboat has structured thought about conservation, economics, ethics, and any number of other disciplinary areas for decades. The question I would like to pose is the following: Is the lifeboat scenario still (or was it ever) an apt metaphor for structuring thought about ethical conservation of resources, or have we reached a stage where the boat should be scuttled in favor of either a new metaphor or more literal language? Please feel free to post any thoughts you may have on this issue.

About the author:  Leif DeVaney is a PhD candidate in the Conservation Biology Program with a minor in Philosophy at the University of Minnesota, and obtained his MS in Conservation Biology from the U of MN in 2010. A native Minnesotan, Leif studied philosophy and biology at Bethel University as an undergraduate. His master’s research included a Q study focused on the conflict over all-terrain vehicle use on Minnesota public lands, and he has performed social science research with the USDA Forest Service. Leif is broadly interested in philosophy of conservation and the interactions of wildlife, humans, and technology, and his doctoral research is centered on an investigation of and argument for the compatibility of wildlife rehabilitation and conservation. Leif is advised by Dr. David Bengston.


PLEASE NOTE: Opinion blogs do not necessarily represent the unanimous opinion of those affiliated with the Conservation Biology Program at the University of Minnesota. Rather, they are meant to broaden and elevate the educational and scientific discourse related to various topics in conservation biology

FWCB Quantitative Ecologist – candidate interviews week of 4/1

The FWCB department search for a new quantitative ecologist faculty position continues this week with Dr. Elise Zipkin. Dr. Zipkin will be visiting Tuesday 4/2 and Wednesday 4/3. Many faculty members in the Conservation Biology Graduate Program are based in FWCB. New faculty appointments have many important teaching and research implications for the department, as well as the CB graduate program. Students are strongly encouraged to attend the graduate student lunch and research seminar as feedback from students is critical in informing the selection process. Research seminars can be accessed through a link on the FWCB website (right side of page) if you cannot attend in person. Please contact Nancy Rothman in the FWCB office for more information about the candidates.

The graduate student lunch with Dr. Zipkin will be this Wednesday (4/3) in 100 Skok Hall from noon to 1. A research seminar will follow at 3pm in Hodson 495. We hope to see you there!

Dr. Elise Zipkin is a Postdoctoral Researcher for the USGS Patuxent Wildlife Research Center in Laurel, MD. Dr. Zipkin received her Ph.D. in Biology in 2012 from the University of Maryland. Her research focuses on hierarchical models of species distributions and abundances.

A big thank you to those of you that have attended the previous activities for the other candidates!