Wearable tracking and biologging devices are rapidly gaining popularity as an assessment tool in the field of animal welfare. From these animal-borne trackers, we can collect a wide range of behavioral and environmental data. Trackers commonly collect information on an animal’s location, activity level (e.g., playing, feeding, or resting), and air temperature. One of the greatest benefits of using this technology is our ability to collect incredibly accurate, fine-scale, and continuous data.  

Similar to many of the features on a Fitbit© or Apple Watch©, researchers and animal care specialists can monitor an individual animal’s activity levels using small, wearable biologging devices. Animal care specialists train the animals to wear these non-invasive trackers throughout the day. For example, a giraffe will present their foot to have the wristband tracker wrapped around their ankle or a dolphin will swim next to an animal care specialist to have a tracker with dolphin-safe suction cups placed on their back.  All of the devices are worn voluntarily, and the animals can choose to remove them at any time.

In the world of electronic devices, dolphins present some unusual challenges because they are aquatic mammals who spend all of their time underwater. Tracker have to withstand being underwater for extended period and continue to function under increased water pressure as the dolphin dives to the bottom of their habitat.  

Researchers at Woods Hole Oceanographic Institution originally took on this challenge and developed a whale tracker called a Digital Acoustic Recording Tag or DTAG in order to conduct studies on the response of wild whales to anthropogenic (human-made) sound. DTAGs have a suite of onboard sensors that record the whale’s geographical location, vocalizations, heading, and acceleration. For the last three years, we have been collaborating with the Shorter Lab in the Engineering Department at the University of Michigan to develop a version of the DTAG specifically designed for bottlenose dolphin in zoos and aquariums called the Movement Tag or MTag. Since Dr. Conners first introduced this research project, we have made significant strides in developing and customizing the MTag. The MTag is similar to the DTAG but it has a few different sensors. The hydrophone and GPS system were removed, and we added a pressure sensor and speed sensor. The tag was also scaled down to be little smaller in order to specifically fit bottlenose dolphins.  

While most land mammals have their feet on the ground, dolphins move vertically and horizontally through their aquatic environment. They have the freedom to move in many ways that land mammals cannot and occupy all three dimensions of their space. Instead of moving in linearly (such as standing, walking, and running) dolphins regularly spin, roll, glide, and jump. Capturing all of their acrobatics to determine their activity level is quite a challenge.

To record all of this information, MTags host a suite of onboard sensors. The sensors record data on 1) the acceleration of the dolphin on three axis (yaw, pitch, and roll); 2) the heading or direction the dolphin is facing; 3) the depth of the dolphin in the water column; 4) the speed of the dolphin relative to the water; and 5) the temperature of the surrounding environment. 

Using these sensors, we can calculate how far a dolphin swims, how much energy they use, and generate 3D representations of how dolphins use their habitat over the course of the day. Having access to this incredibly detailed information helps us ensure that our dolphins are engaging in healthy daily exercise and learn more about how they use their environment! 

Published July 5, 2019