Understanding the American marten could aid conservation, but habitat loss threatens its existence

The American marten is more than just Maine’s cutest carnivore. The marten, which is prevalent throughout the state’s forests, can tell scientists a lot about the population dynamics of a number of other mammals, but forest disruptions and climate change threaten the species’ existence.

A group of University of Maine researchers led by Alessio Mortelliti, an associate professor in the Department of Wildlife, Fisheries and Conservation Biology, found that the American marten could serve as an effective “umbrella monitoring species” for 11 other mammal species in Maine. Umbrella monitoring species are those whose monitoring efforts are also found to overlap with a number of other species. As such, they are useful in reducing the effort required for important monitoring programs, which collect repeated observations or measurements of wildlife to ensure environmental management goals are being met.

The marten may need more attention now than ever, as the loss of mature forests and habitat fragmentation have led to a decrease in marten populations. Their habitat overlaps with areas of interest for Maine’s forest industry, and climate change continues to transform the forests.

In a study published in the journal Nature Scientific Reports, UMaine researchers monitored 197 survey sites across Maine. They used camera traps, which are digital cameras that automatically take a picture when their infrared sensors are triggered by movement, like that of an animal, to take over 800,000 pictures of 27 different mammalian species over a four year period. 

The results showed that monitoring the American marten has an “umbrella effect” on 11 other mammals when it comes to detecting different magnitudes of population decline. The effectiveness varied depending on the species, with fishers, snowshoe hares, red squirrels and black bears consistently covered under the American marten “umbrella,” while porcupines and bobcats were least covered. 

Still, the findings show that multispecies monitoring is feasible, especially with an effective umbrella monitoring species like the American marten.

“These results are exciting as they show that up to 11 mammalian species can be monitored simultaneously. This is great news for conservation and management agencies as they show that by focusing the efforts on one species, the marten, they will automatically be able to detect declines for many other species. This could lead to huge savings, which is not a small thing in a world where conservation resources are so limited,” says Mortelliti.

The American marten monitoring study, which was funded by the Maine Department for Inland Fisheries and Wildlife (MDIFW) and the Cooperative Forestry Research Unit (CFRU), is now in its fifth year, with over a million photographs. The researchers have focused on developing a monitoring protocol specifically for the winter season, when detection of protected species, such as the Canada lynx, is more likely. The American marten monitoring protocol could be applied for monitoring in similar, temperate ecosystems in North America and Europe.

That is, of course, if American marten populations can survive the disruption and destruction of their forest habitats. Mortelliti and his team have also studied the way that martens and their close relatives, the fisher, have responded to disturbed forest habitat in Maine. The researchers took their camera trap observations of the two species and looked at the sites where martens and fishers were found. They compared the importance of latitude and snow depth, the intensity of forest disturbance through remotely sensed images, and the reported numbers of marten and fisher by fur trappers on marten and fisher occurrence. 

The results, recently published in the journal Ecosphere, showed that areas with more recent and more intense timber removal activities negatively affected marten and fisher populations.

“We thought perhaps marten would be negatively influenced by the presence of the larger fisher, but our data indicated that’s not really the case here in Maine,” says Bryn Evans, recently graduated Ph.D. student and co-author of the study. “Instead, marten are choosing areas with the least forest disturbance, regardless of fisher presence. Climate change is also likely to impact marten more intensely than fisher. It’s critical to have a watchful eye over the coming years, so declines in the marten population can be identified quickly. That’s why it’s so wonderful that MDIFW will be continuing to monitor these species going forward.”

Contact: Sam Schipani, samantha.schipani@maine.edu