Drones & Marine Mammal Health
Drone photograph of three harbor seals hauled out on some rocks to sunbathe in Saint John, New Brunswick.
Using Drones to Study Marine Mammals
Marine mammals are inherently cryptic species; they spend most of their time underwater and have very wide geographic distributions, making it difficult to study these animals up close.
​
Recent advancements in the technology of remotely piloted aircraft systems (RPAS, more commonly known as "drones") have allowed for unique opportunities to study marine mammals at sea. The aerial perspective allows researchers to obtain stable, full-body, high-resolution imagery of animals. Still photographs can be used to measure the length and width of animals (called photogrammetry), assess health (by quantifying parasite loads or evaluating body condition), and investigate human impacts (by looking for entanglements, injuries or scars). Videos are being used to analyze the behavior and social interactions of marine mammals, too.
Drone-based Infrared Thermography
Infrared thermography (IRT) measures the heat that is naturally emitted from objects. IRT sensors can now be flown from drones, which means we can investigate the heat signatures of animals that are hard to access with minimal invasiveness!
​
Colleagues at the Woods Hole Oceanographic Institute, New England Aquarium, and US Navy and I recently collaborated on a project using drone-based IRT to investigate the heat signatures from North Atlantic right whales in Cape Cod Bay, Massachusetts. We observed three thermal phenomena that provide important insights into the physiology and conservation of the species (see figures below):
1) Right whales exhibit unique heat signatures from their head, where their callosities (white, thickened,
keratinized tissue) appear cooler than surrounding tissue.
2) When traveling sub-surface, right whales "kick up" cooler water - called "fluke prints", which could allow
them to be more easily tracked when not visible at the water surface.
3) One whale exhibited an anomalous heat patch on its back; this whale gave birth to a calf 8 months
later, suggesting that excess heat generated during pregnancy, injury, or disease could be detected and
monitored with drone-based IRT.
​
These results were published in Endangered Species Research in July 2022.
Time-aligned video frames from a thermal camera (left, white-hot color palette) and a GoPro HERO3 (right), demonstrating the heat loss patterns relative to the callosities on the head of a North Atlantic right whale.
Time-aligned video frames from a thermal camera (left, white-hot color palette) and a GoPro HERO3 (right), demonstrating the cool thermal fluke prints (white arrows) that were generated during fluke upstrokes from two traveling North Atlantic right whales.
Time-aligned video frames from a thermal camera (left, white-hot color palette) and a GoPro HERO3 (right) illustrating heat from the back of an adult female North Atlantic right whale, which was likely pregnant at the time the video was taken.
Time-aligned video frames from a thermal camera (left, white-hot color palette) and a GoPro HERO3 (right), demonstrating the heat loss patterns relative to the callosities on the head of a North Atlantic right whale.
Figures from Lonati et al. (2022) - "Investigating the thermal physiology of Critically Endangered North Atlantic right whales Eubalaena glacialis via aerial infrared thermography", published in Endangered Species Research.
My PhD Research
What we were unable to achieve in our study in Cape Cod Bay was quantifying temperatures we observed with drone-based IRT. This became one of the objectives of my PhD research in the Davies Lab at UNB Saint John.
To obtain absolute temperatures, colleagues and I have developed a drone system and specific protocols* to calibrate measurements obtained with our drone's thermal camera. Using these protocols, I am investigating whether blowhole temperatures could be used as an indicator of whale health (similar to using contactless thermometers to detect fevers in humans). This research will also involve photogrammetry, which uses the altitude and focal length of a camera to derive two-dimensional measurements from pixels in photographs. Photogrammetry is already a well-established method to evaluate the body condition (or estimate of fat reserves) of whales.
​
See below and my gallery for some preliminary thermal and visible-spectrum footage from my drone research!
​
*I am currently in the process of writing and publishing these protocols, so check back soon for more information, or contact me if you're interested in using these protocols for your own research!
Simultaneous visible-spectrum (RGB) and thermal video of a humpback whale coming to the water surface for a breath. Note how the blowholes appear hotter (whiter) than the rest of the field of view.
A humpback whale comes to the surface to breathe in the Bay of Fundy, Canada.
Note the heat from the blowholes, but also the irregular splotches on the whale's back.
Note the pattern of heat loss around the head and appendages.
A humpback whale comes to the surface to breathe in the Bay of Fundy, Canada.