Researchers in the Bayne Lab at the University of Alberta have been refining remote camera protocols to monitor small mammals on human footprint features in the boreal. While methods to capture medium- and large-sized mammals on cameras are well-established, small mammals require their own approach that accounts for their quick movements and nocturnal behaviour.
Alessandro Franceschini has been using camera traps to monitor small mammals in northeastern Alberta for the past two years. Bijaya Dhami is investigating how small mammals respond to different forest harvesting practices in boreal forest and foothills of Alberta. Both projects are published and available to explore on Data Discover!
Monitoring small mammals on linear features
The boreal forest and foothills of Alberta have rapidly industrialized in the past five decades, primarily driven by forestry, energy, and mineral extraction. Understanding how species are responding to these changes is critical to sustainable resource development and preventing biodiversity loss.
Linear features are the most widespread disturbance in the northeastern boreal forest, with an average density of 2.7 km/km2 across the Boreal Forest Natural Region. While the impacts of seismic lines on large mammals such as wolves and caribou are well-studied, small mammals—crucial for ecosystem functioning and forest restoration processes—have often been overlooked.
From June to August 2023, Franceschini deployed 528 cameras in the Lower Athabasca Region in Alberta across gradients from upland to lowland forest and of linear feature width. The width of the linear feature was found to be the primary driver of whether or not different small mammals were detected. Interestingly, habitat type wasn’t strongly correlated with any small mammal except for red squirrels, and the only species whose detection varied by time of year were shrews, which were almost entirely absent in June. All in all, the differing reactions among species led to substantial variations in species composition among the study sites.
Assessing the effectiveness of forest retention practices
Clear-cutting is a form of forest management that can have detrimental impacts on biodiversity, particularly for mammal species that rely on specific forest structures for shelter and foraging. In response, forestry companies have increased the amount of residual retention within harvested areas, based on the premise that preserving elements of the original stand offers both short- and long-term benefits for species.
Dhami evaluated the effectiveness of stubbing as a forest retention practice in sustaining small mammal populations and enhancing habitat heterogeneity in Western Alberta’s foothill forests. Small mammal surveys were conducted across 67 sites using a paired block design with motion-triggered camera traps. Preliminary results indicate that stubbing areas within harvested sites exhibited greater species richness, with higher occurrence and abundance of forest-dwelling species such as the southern red-backed vole (Myodes gapperi) and red squirrel (Tamiasciurus hudsonicus). In contrast, generalist species like the deer mouse (Peromyscus maniculatus) were more abundant in areas of blocks that were clear cut. Stubbing appears to be a valuable tool for mitigating biodiversity impacts and enhancing habitat complexity in managed forests, helping to balance timber production with conservation objectives.
How to monitor small mammals with remote cameras
While remote cameras are widely used to monitor medium- and large-sized mammals, consistently capturing small mammals such as voles and shrews remains a challenge with this technology. The Bayne Lab researchers modified an existing method—the “selfie method” of Gracanin et al. (2019)—to capture photos of small mammals. The modified version consisted of attracting the animals into a baited PVC pipe that is 7 cm in diameter, one end of which is open and one end of which is closed with a PVC cap. A white flash camera, with its focal length adjusted, was securely anchored to the ground using a stake positioned 25 cm from the entrance to the pipe. This method resolves several issues frequently encountered in studying small mammals with cameras:
- Capturing distinguishing features: White flash cameras can capture high quality, full-colored images and videos at night and help more readily identify species than those obtained under infrared light (which are black and white). The use of bait also helps capture clear photos of the animals as they spend more time not moving around. Finally, forcing the animals to use the pipe so they pass by the point where the focal length is set improves the ability to identify the animals.
- Portability: This method is very “light weight” and portable compared to others that involve the use of buckets or the Mostela method. This is a great advantage for studies that are carried out in remote environments that are hard to navigate, such as the boreal forest.
- Bait shelf life: Putting bait (in this case, a mixture of peanut butter, oats, and honey that even a field biologist would love) inside the pipe slows the drying process by shielding it from sunlight and wind.
With modifications such as these, remote cameras can be an effective tool for researching small mammals.