U of I Biologists get help from engineers to study river otters

U of I Biologists get help from engineers to study river otters

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Biologists who study North American river otters in the wild face some unique challenges. Otters cannot be fitted with collars, because their heads are smaller than their necks, so their movements can’t be traced with the sort of GPS setup that might be employed to track foxes or coyotes. And it’s rarely possible to distinguish one otter from another in images captured by trail cameras, so there’s a real limit to what can be learned from those.

According to Samantha Carpenter, however, it’s important for scientists to overcome those challenges. Carpenter is a researcher who works in the lab of Nohra Mateus-Pinilla, who studies the ecology of wildlife diseases at the Illinois Natural History Survey.  Because river otters are top predators in many aquatic ecosystems, Carpenter points out, otter management has system-wide impacts, beginning with the many creatures they eat, including fish, mussels, frogs and crayfish.

River otter populations in Illinois have recovered dramatically over the past two decades, from a low of fewer than 100 animals in 1989, when they were listed as endangered in the state, to current numbers, which are estimated to exceed 11,000.  Their recovery is attributable in part to the recovery of aquatic habitats, which have improved so much thanks to the Clean Water Act, and in part to the otters from other states in the mid-1990s, which kick-started the current population boom.

The questions Carpenter and Mateus-Pinilla seek to answer include: How much space does an otter occupy as a home range? Are there seasonal patterns in their use of habitat? What factors affect the size, structure and interactions of their social groups? Answering these questions requires the capacities to trace the movements of individual otters and to distinguish among individuals. Both of these can be facilitated with the use of cutting-edge technology.

Over the past year, Mateus-Pinilla and Carpenter have received help in this regard from people who normally think very little about otters--or wild animals in general--faculty and students from the UI Department of Electrical and Computer Engineering (ECE). Each semester, ECE students enrolled in Senior Design work in teams and select among projects pitched to them by researchers who need real-world assistance.

What have they done for the otter researchers? One team has developed a device that is already deployed at a location near the Salt Fork of the Vermilion River called the “Otter Print Shooter.” It’s a box with a clear acrylic top that contains a digital camera and is buried near a site otters frequent. By means of a sophisticated arrangement of sensors, triggers and lights, the device captures detailed images of otter paw prints. These images enable the researchers to identify individual otters the way fingerprints are used to identify humans.

[Photo, left to right: Nohra Mateus-Pinilla, Yon Chiet Ng, Hui Lin Ng,  Sabrina Yan Ru, Hoong Chin Ng,and Samantha Carpenter deploy the digital tracking plate. Photo Jen Mui.]

Other teams have developed similarly ingenious and useful projects. One has created a system to track individual otters by means of an implantable chip similar the ones used to identify pet dogs and cats. Another is working on an implantable GPS chip, which would enable researchers to trace the movements of individual otters across the landscape via satellite.

Samantha Carpenter describes the fruits of this collaboration between wildlife researchers and engineers with great enthusiasm. And she also looks forward to all that these tools will enable her and others to learn: “Whereas many people view the recovery of river otters in Illinois as a happy ending to their story, we view it as the beginning of an exciting sequel.”