Nature Lab

Wildlife Management

Tracking River Otters

Many animals can be radio tracked with GPS collars or backpack transmitters with signals detected by satellites. But otters present a special challenge. 

“Otters are extremely flexible and are always cleaning and pulling at anything and everything on their body,” explains Furbearer Biologist Nate Bowersock. “And if they’re with other otters, the other otters help them remove those devices.”

The solution? Insert a small transmitter under the skin of the otter’s abdomen. This method has been successful with traditional VHF transmitters, but those transmitters come with a time-consuming drawback. 

“With standard radio telemetry,” Bowersock says, “you have to go out and physically track the animal. You’re sending people out every day or every few days to find them.”

So, MDC is testing a newly developed transmitter for tracking otters that uses Global System for Mobile Communication (GSM). GSM transmitters are the part of a cell phone that connects to cell towers. Ideally, when an otter ventures within a few miles of a cell tower, the tower will detect the transmitter signal, and a message will be sent to researchers. 

“These new transmitters, if they work, would reduce a lot of time spent going out and tracking these animals,” says Bowersock.

As a pilot study, 10 otters will be captured around Boone County, and a veterinarian will surgically implant the transmitters. The transmitters will function as both GSM and VHF, so staff can also track the otters the traditional way and compare their findings to determine the accuracy of the GSM detections. 

If the new transmitters prove accurate, 50 more otters around the state will be fitted with them. Survival information gained through tracking will be added to data gathered from otters harvested by trappers to improve population estimates used for management decisions.

At a Glance

Before embarking on a larger study to track otter survival, MDC researchers are testing a new transmitter that could prove both timesaving and cost effective. Radio tracking otters will provide the survival information needed to improve estimates of how many otters live in the state.

1. Signal from a tracking device in the otter is detected by a cell phone tower.
2. The cell tower then connects to a program that sends a message to the researcher.