Wolverine Ecology
in the
Teton Range of Western Wyoming

Project Update: 1998-1999 Trapping Season

Our primary interest this past winter was in learning whether or not our instrumented female would produce a litter of kits. Very little is known about wolverine reproduction and it is our hope that by closely monitoring her movements throughout the denning period (February-March), we will find her localized at the den site. An improved knowledge on den site selection may be critical to land-use management relative to wolverine.

Trapping was initiated in early January. We recaptured Annie (F468) on January 19. It was our hope that we might recapture her early in the winter, prior to the birth of any kits. We want to handle female wolverine that are potentially lactating as little as possible once the kits are born. By capturing females prior to birth, we can collect a sample of blood and measure certain hormones that indicate pregnancy. This confirmation of pregnancy makes our job of determining kit presence significantly easier as field confirmation of kit presence can be extremely difficult. Unfortunately, at this recapture we were unable to collect a sample of blood. It then became necessary to determine the presence of kits by monitoring her movements during the denning period. We began closely monitoring Annie's (F468) movements in mid-February in hopes that we would find her activities reduced as she approached the denning period.

As denning time nears, the female's movements should become reduced as she spends much of her time near and in the natal den. By flying several times daily, we should be able to document this reduced activity and eventually locate her in the den itself. We conducted 11 telemetry flights during March, but F468 showed no indication of reduced movement, and thus, no indication of denning activity. On April 21, Annie was again recaptured giving us an opportunity to actually confirm the presence or absence of kits by determining whether or not she was lactating. We found she was not, confirming that she produced no kits, at least none that survived, for the second year in a row. Studies in both Alaska and Idaho have reported similar results -- very low reproductive rates in wolverine. Another study presently underway in British Columbia is reporting similar findings. Annie's radio should last through next April. Hopefully, she will produce a litter next year.

In addition to monitoring Annie, the project captured and instrumented 2 additional wolverine. On March 7, an adult male was captured (M399, aka Danny). We are only beginning to monitor his movements and outline his home range. He has used nearly the entire Teton Range, so it will be a while until we learn the extent of his area.

In April the project captured a second female (F379), in an area to the south of Targhee Ski Resort. She was captured in a barrel trap enabling us to transport her to the Driggs Veterinarian Clinic for processing. We believe she is likely a 2-year-old and has not yet produced her first litter of kits. She could potentially mate this summer and produce her first litter next winter.

Throughout the summer we will monitor the wolverines weekly. We will learn about their use of various habitats in the Tetons and how they relate to each other as we see their home ranges develop.

If you would like to provide some generous help for this project, you can make a tax deductible contribution through The Wolverine Foundation, Inc. at the address listed below. Just let us know that you would like your contribution directed to the Teton Wolverine Project in your correspondence.