SMSC Diary (Week 11): Camera Trapping at SCBI/SMSC

Prior to this semester at SMSC, I had no experience with camera trapping. I knew photos of animals passing the traps could be captured, but that was the extent of my knowledge. Little did I know, scientists could gather information on the species richness of an area (how many different species are present), as well as the habitat use and activity patterns of animals. To demonstrate these applications, each WEC student was given a camera trap on September 21, 2016 and assigned three tasks:

1. Expand the mammal species photo list (collected from prior semesters) on SCBI property to contain semi-aquatic species (i.e. living partly on land and partly in water).

2. Compare capture rates at water features to trails from previous semesters.

3. Compare the activity pattern of animals observed on camera traps.

Pro: Camera traps can passively collect data for 24 hours a day, 7 days a week less expensively than hiring a field crew to monitor animals. Additionally, animals are less likely to alter their daily routines around a small camera, as opposed to a large human(s) that carry scents, move, and may do other things to alter the otherwise wild habitat.

My camera trap was placed at Bear Pond on a tulip poplar tree, along the edge of the pond farthest from the road. The trap was surrounded by a dense canopy of tree cover (good to avoid the trap getting set off by the movement of sunlight, as the camera is triggered by heat) between a sloping hill covered in leaf debris and the pond. A fallen log lay directly across from my trap connecting the pond and the hill – a good platform for movement, as I later discovered.

After 47 “trap nights”, or nights that the camera was turned on waiting to capture photos, I collected 943 photos total consisting of the following species: bobcat (Lynx rufus), mouse species (Peromyscus sp.), white-tailed deer (Odocoileus virginianus), hairy woodpecker (Picoides villoscus), raccoon (Procyon lotor), eastern gray squirrel (Sciurus carolinensis), American black bear (Ursus americanus), and human (Homo sapien).

Con: Camera traps rely on battery power that may run out dependent on trigger frequency (how often the trap is set off), which resulted in less trap nights for some students during our study.

While I only found 7 species (not including the human whom collected my trap at the end of the 47 days), our WEC class collectively found 13 different species, two of which included the North American river otter (Lontra Canadensis) and the common mink (Neovison vison) not previously documented by SMSC students that observed surrounding trail habitats. An example of each of the species captured on my trap can be found below.

Bobcat

Mouse species

White-tailed deer

Hairy woodpecker

Raccoon

Eastern gray squirrel

American black bear

Human

Once our class processed all of our photos (i.e. looked at all every photo and sorted based on species present) we then calculated the activity patterns for three species: the gray squirrel, white-tailed deer, and raccoon. We were able to do this by categorizing the photos based on the time stamp on each photo event (cluster of photos within a 10-minute trigger interval), relative to the percent of overall photos captured during that time period. The results were as follows:

• Eastern gray squirrels: peak activity levels during day (i.e. diurnal)

• White-tailed deer: peak activity levels around dusk and dawn (i.e. crepuscular)

• Raccoons: peak activity levels dusk through dawn (i.e. nocturnal)

These activity patterns were only apparent when the data was combined, as a class because a minimum of 30/40 photo events are required to illustrate distinct patterns. Additionally, since this was the first time analyzing camera trap data for many students, it is possible that we may have missed animals that weren’t as obviously present therefore limiting our results.

Even though it took me about 2.5 hours to sort through all of my pictures (hundreds of which were raccoons), each new picture was as exciting as the very first. This experience left me feeling like I was given a glimpse into a secret world. Now, anytime I pass an area with a fallen log or a hole that looks like it could make a nice den I think about how I would set a camera trap to capture the visitors that frequent the area when no one is looking.