Refuge Notebook: Unveiling the secret lives of elusive wolverines, part 1

Posted: Friday, November 12, 2010

Consider yourself extremely lucky if you have ever seen a wolverine in its natural habitat because wolverines are one of North America's rarest and least known large carnivores.

Photo By Ted Bailey
Photo By Ted Bailey
A wolverine fitted with an early conventional radio collar by the author in Montana during the winter of 1972-73. Today radio collars incorporate GPS technology programmed to obtain thousands of locations per week.

Little was known about the lives of free-roaming wolverines until the early 1970s when the first study of these elusive mammals using radio telemetry was conducted in northwestern Montana under the direction of Dr. Maurice Hornocker at the University of Idaho's Cooperative Wildlife Research Unit.

I was fortunate to play a small role in this pioneering study. I had just finished a research project on the ecology of bobcats for my doctorate at the University and Dr. Hornocker was my graduate advisor. When he asked if I would conduct a brief feasibility study of wolverines within the Flathead National Forest (southwest of Glacier National Park) in northwestern Montana, I immediately accepted and moved my young family to the little town of Hungry Horse during the winter of 1972-73.

My task, working with a local trapper, was to assess different techniques for capturing wolverines alive, determine immobilizing drug dosages and find out if radio collars could be used to study wolverines. During that winter we captured, ear tagged and released four wolverines, one of which I temporarily fitted with a radio collar.

Based on wolverine tracks in the snow and capture locations, I estimated a density of 1 wolverine per 20 square miles and recommended continuing a long-term study. A colleague, Howard Hash, continued the study through 1977. He captured an additional 20 wolverines, fitted them with radio collars, and was the first to document the wide-ranging movements, habitat use and vast home ranges typical of wolverines.

Since this first study of free-roaming wolverines in Montana, further research has steadily revealed more information about the lives of wolverines. The first radio telemetry study in Alaska was conducted from 1978 to 1981 by Audrey Magoun for her PhD project. Initially she studied wolverines in tundra habitat in the northwestern part of the state, but has continued to conduct research on wolverines in Alaska and has developed new study techniques. She is one of the directors of The Wolverine Foundation, a non-profit organization of wildlife scientists interested in wolverines.

Several innovative research techniques have been used to advance our knowledge of wolverines since the early Montana study. Box-type live traps made of logs are now used to efficiently capture live wolverines in forested habitats. Radio collars are smaller, function longer and can include GPS technology programmed to obtain thousands of locations per week. Small radio transmitters have also been surgically implanted within the body cavities of some wolverines instead of placing radio collars around their thick muscular necks.

Self-triggered remote cameras combined with devices to collect hair samples for DNA analysis are also now being used to study wolverines. This permits wolverines to be identified as individuals and reveals their sex and reproductive status. DNA analysis can distinguish individual wolverines as well as reveal maternal and paternal relationships among wolverines. The advantage of the hair DNA technique is that the wolverines do not have to be captured in order to obtain important genetic and population information.

Some of the most surprising information about the previously unknown social life of wolverines has just come from a recent long-term study using GPS collars and DNA analysis in Glacier National Park in northwestern Montana. Previously thought to be solitary and asocial, wolverines turn out to be quite the opposite. Male wolverines mate for life -- up to 8 to 10 years -- with 2 to 3 females, each of which maintains an exclusive home range. The males not only breed with these females, they make periodic visits to the females' den sites -- apparently to protect their young from other males -- and later spend time traveling together with their developing offspring.

I encourage readers to watch the PBS Nature program "Wolverines: Chasing the Phantom" at 8 p.m. Sunday, Nov. 14. I also recommend the recently released book "The Wolverine Way" by Douglas Chadwick. The Wolverine Foundation website provides further information at:

This article will be continued in next Friday's Refuge Notebook.

Ted Bailey is a retired Kenai National Wildlife Refuge wildlife biologist who has lived on the Kenai Peninsula for over 34 years. He maintains a keen interest in the Kenai Peninsula's wildlife and natural history.

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To report unusual bird sightings or hear what local birders have been seeing, call the Central Peninsula Bird Hotline at 262-2300. Previous Refuge Notebook articles can be viewed on the refuge website

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