Notes from the Field: Recovering American Martens

The Detroit Zoological Society (DZS) is continuing its efforts on an American marten conservation project in the Manistee National Forest. This spring, I was given the exciting opportunity to assist collaborators from Grand Valley State University and Busch Gardens on this project. Martens are small, weasel-like carnivores that became extirpated (locally extinct) from the lower peninsula of Michigan in the early 1900s because of habitat loss and unregulated trapping. Martens were reintroduced back to the Manistee Forest more than 30 years ago, and since 2013, veterinary and animal care staff from the DZS have been helping to study the success of the marten reintroduction by looking at animal health, kit survival and habitat use. This work involves collecting martens in live traps and then anesthetizing them in order to perform physical exams and collect samples of blood, hair, urine and feces. The DZS uses Hav-A-Heart traps, humane traps that close in such a way that they do not harm the animal. The traps are set carefully to ensure that martens have a nice snug spot. We cover each trap with pine needles and leaves for warmth and nest building, and ensure the martens have a snack and a source of water. The collected samples are then tested for disease. The project also uses GPS and radio tracking collars to gather information on marten habitat use and determines which forest types they prefer.

My time spent in Manistee involved daily morning checks of approximately 30-40 live traps for martens. If a marten is in a trap, it is then transported to the bed of a pickup truck in order to induce anesthesia and be examined. Special care is taken to monitor the marten’s body temperature to be sure that it does not become too hot or too cold during the procedure, and after samples are collected, a GPS collar may be placed on the marten to track habitat use. When the procedure is complete, the marten recovers in a small, dark wooden box until it is stable enough to be released. Once stable, a staff member opens a little door on the box and the marten runs off back into the forest. This entire process usually takes about 30 minutes from beginning to end.

During my time assisting with the project, I spent many hours riding down narrow, bumpy and winding two-track forest trails. Some of these trails were quite precarious, but travelling them gave me the opportunity to see migrating birds, deer, a porcupine and even a black bear! We were able to collect samples from four martens and place GPS collars on three of those four, dramatically increasing the amount of data collected on marten habitat use. These GPS collars were purchased with financial support from the DZS, and the data will be used in collaboration with the U.S. Forest Service to decide how the forest can best be managed to facilitate recovery of the marten population. It was thrilling to be a part of this project and I am thankful to the DZS for allowing me this opportunity.

– Erica Campbell is a veterinary technician for the Detroit Zoological Society and works in the Ruth Roby Glancy Animal Health Complex at the Detroit Zoo.

Notes From the Field: Martens in Manistee

Paul Buzzard, Ph.D., is the director of conservation for the Detroit Zoological Society.

I recently returned to northern MichiganFile photo with staff from the Detroit Zoological Society (DZS), Grand Valley State University (GVSU), and Busch Gardens to continue studying the behavioral ecology and conservation of American martens. American martens are small carnivores that are weasel-like and largely arboreal, which means that they live in trees. They were hunted out in Michigan’s Lower Peninsula by the early 1900’s and reintroduced to the Manistee National Forest nearly 30 years ago.

We are studying the success of marten reintroduction by looking at marten health, survival of their offspring, known as kits, and habitat use. These data will be used to see how the forest can be better managed by the U.S. Forest Service to benefit martens.

File photo DZS veterinarians have helped in the past to put radio-telemetry collars on the martens to track their locations. However, this technique, which involves capturing the martens in live traps, is very labor-intensive, and only provides information on marten locations a few times per week. The DZS provided funds for GPS collars that use satellite positioning data to record marten locations every half hour and gather much more accurate information on marten ranging and habitat use. In fact, we’ve been able to retrieve data from one of the collared martens and it is giving us great information on how the marten is using his habitat.

During this visit, our task was to help set the live traps with venison as a tasty treat for the martens and placing a stinky concoction called “Gusto” around the traps to attract martens from far away. We captured one marten, but as it turns out, that marten had been previously collared. This marten was special, however, because it had been orphaned and fed by GVSU students until its independence. The marten’s mother had been found dead on the side of the road, so the students decided to catch mice and leave kitten chow for the young martens left behind until they reached adulthood.

We also had the opportunity to follow two other martens wearing radio-telemetry collars. We were able to see the tree dens they were using and observe the martens high up in the trees. All in all, it was a wonderful trip.

– Paul Buzzard

Veterinary Care: Martens in Manistee

Dr. Ann Duncan is the chief veterinarian for the Detroit Zoological Society.

One of my favorite things to do is assist with work in the field. It is very rewarding to be able to use our veterinary expertise to help animals succeed in their natural habitat. This month, I and Dr. Wynona Shellabarger each had the opportunity to spend a few days near Manistee in northern Michigan, assisting with health assessments of free-ranging martens.

The American pine marten (Martes Americana) is an important carnivore species that was originally found throughout most of our state. Habitat loss and overhunting led marten populations to drop to zero by the early 1900s. In 1986, the U.S. Forest Service and Michigan Department of Natural Resources reintroduced 36 martens into the Manistee National Forest. Early monitoring of the released animals indicated that the population was not expanding as expected. Professor Paul Keenlance from Grand Valley State University has been leading research efforts to better understand this group’s habitat range and preferences, breeding success, and the distribution of their young, known as kits.

His research team is also working to better understand what they eat and to determine the degree of genetic diversity. The Detroit Zoological Society’s (DZS) participation is in support of the work Dr. Maria Spriggs from Busch Gardens is leading to assess the overall health of the Ann Duncan - Martenpopulation. To conduct this research, the martens are captured in what are known as Hav-A-Heart traps – which are humane traps that close in such a way that they do not harm the animal. The traps are set carefully to ensure that martens have a nice snug spot. We cover each trap with pine needles and leaves for warmth and nest building, and put large pieces of bark on top to protect them from rain and snow. We also place meat bait and grapes in each trap so that they have a snack and a source of water.

Our visit this spring marked our fifth trip to the field site. A typical day in the field starts at 7 a.m. because we want to make sure that any martens that have been captured do not have to wait long. Each trap is marked on a map with GPS coordinates and we drive from one trap to the next. Empty traps are restocked with bait and grapes as needed.

Ann Duncan - martenIf we catch a marten, things get very exciting. Each marten is given anesthetic gas with a face mask to allow an examination. During the procedure, we measure several parameters to ensure that anesthesia is safe and smooth. We measure body temperature to make sure martens are not too cold or hot. Next, we collect a body weight, perform a thorough physical exam, check the teeth to determine age and check for ticks and fleas. We collect urine, feces and hair samples, and collect blood for an overall health panel and to determine exposure to viruses. Lastly, each marten is fitted with a GPS collar. The DZS provides GPS collars that are able to provide a location every 15 minutes to an hour for many months.

During a typical week, we usually catch between five and 10 martens. Each capture expands our understanding of these amazing creatures. The information that has been gathered so far has lead to changes in the management of the forest in which they live, and will be used to inform decisions about marten protection in the future.

– Dr. Ann Duncan