- Managing forests for marten
- American marten (Martes americana americana)
- Newfoundland marten (Martes americana atrata)
Managing forests for marten
The American marten (Martes americana), also referred to as the pine marten, is a shy weasel-like mammal found throughout Canada in coniferous and mixedwood forests. Marten has traditionally been prized by trappers for its high-value fur, sometimes referred to as Canadian sable.
A sub-species of the American marten, the Newfoundland marten (Martes americana atrata), can only be found on the island of Newfoundland and on the Labrador peninsula. In 2007, Newfoundland marten were reclassified from endangered to threatened under the federal Species at Risk Act and the provincial Endangered Species Act.
Gaps exist in what we know about the long-term effects of forestry activities on wildlife species such as marten, which are often used as indicators of forest ecosystem integrity. We know that they avoid young stands in boreal forests, generally preferring mature and older conifers and mixedwoods. Research indicates that intensive silviculture likely decreases desired habitat characteristics for marten in the short-term, because it reduces coarse woody debris and standing dead wood, habitat features important to marten. The effects of changes in forest tree species composition are also of concern.
Canadian Forest Service researchers are studying marten in Newfoundland and Ontario to understand how they respond to forest management practices. This work will enable land managers to make informed decisions that consider the needs of marten habitat.
American marten (Martes americana americana)
A large-scale collaborative field study was initiated in 2000 by the Canadian Forest Service, the Ontario Ministry of Natural Resources and the University of Guelph to gather scientific data about marten populations in managed and unmanaged forests. The research was conducted in two locations in Northern Ontario, near Red Lake and Kapuskasing and concluded in 2007. Each study site was several thousand square kilometres in size, and contained both managed and unmanaged forests.
More than 100 marten, including adults, juveniles, males and females, were captured using baited live traps. Researchers recorded the animals’ weight, age, and sex and then fitted them with small radio transmitter collars. Field crews travelling on foot or by truck, snowmobile or aircraft were then able to obtain daily or weekly signals from the marten over the course of the project. The data gathered were used to estimate the martens’ home range sizes and habitat use, hunting and reproductive success, population density, survival rates, and habitat availability for both marten and its preferred prey, in order to better understand the mechanisms affecting population levels.
The researchers found that marten in managed sites exhibited poorer body conditions and higher rates of juvenile mortality, both of which indicate that they hunted less efficiently in these conditions. However, marten responded positively, but still in low numbers, in managed areas that had been replanted with conifer trees about 50 years previously, suggesting that basic silviculture can eventually provide habitat favourable to marten. Marten populations were also influenced by commercial trapping, showing a higher susceptibility to capture in managed forests, likely due in part to the higher density of road networks that provide increased access to trappers.
The results of the study suggest that mature and older forests provide the most favourable habitat for marten survival in boreal forests. Populations can also persist at lower levels in mature regenerating forests, but only if trapping is controlled. A range of forest ages distributed across the landscape with various sizes of uncut areas would likely be the most effective means of ensuring viable populations of marten, particularly when both fur harvesting and timber harvesting are managed together.
A population viability analysis (PVA) model that uses habitat and population data to predict marten populations has been created by the researchers. The model will be helpful in predicting future population size, as well as determining the forest management strategies that would be most effective in allowing forest harvesting while maintaining viable marten populations.
Newfoundland marten (Martes americana atrata)
The Newfoundland marten is classified as threatened under the federal Species at Risk Act and the Newfoundland and Labrador Endangered Species Act. For over 15 years, Canadian Forest Service researchers, in partnership with the Province of Newfoundland and Labrador, the University of Maine, the Western Newfoundland Model Forest and the forest industry, has been monitoring marten persistence on the island. Early work attempted to understand how martens use the forests of Newfoundland, and why despite decades of protection from commercial trapping their population was limited in distribution to a portion of their historical range. Subsequently, this baseline work was used to build a predictive habitat and population assessment model (Marten Occupancy Model) that could be used to map critical habitat, and assess the potential of areas to support marten. This model is now being used by forest planners to proactively gauge the potential impacts of proposed harvesting plans on marten viability, and to manage marten habitat availability over the landscape.
Currently, CFS is leading a follow up research project on a 617 km2 study area near Corner Brook, of which 51% is designated as critical marten habitat under the Federal Species at Risk Act. A portion of the study area is being harvested over a 5-year period by Corner Brook Pulp and Paper Limited as part of their annual operations.
Researchers trap marten in live traps during two-week periods in summer, autumn and winter. The marten are examined, sexed, weighed, injected with a passive integrated transponder (PIT) tag, and fitted with radio collars. The researchers then intensively monitor the animals from a helicopter, to determine residency, adult survival, survival of dispersing juveniles, cause-specific mortality, and forest use. Locations are plotted using GPS technology, allowing researchers to create territory maps for each marten within the study area.
The study is adaptively monitoring the health of marten populations in an area subject to forest harvesting, providing additional data to modify and test the Marten Occupancy Model used in the province, and assisting in the environmental assessment of proposed harvesting plans. Ultimately, the research will help to assess critical and recovery marten habitat and contribute to the long-term sustainable management of forest landscapes for both marten survival and timber harvest.
Canadian Forest Service key contacts
Brian Hearn, Science Director
Ian Thompson, Research Scientist, Ecology and Biodiversity
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- Mortality risk increase with natal dispersal distance in American martens
- Habitat-mediated variation in predation risk by the American Marten
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