Glow-in-the-Dark Wildlife

As most of you know I lead a charmed life.  Not only do I pursue my passion but I have made a career out of it. Studying wildlife is an adventure uniquely fulfilling yet I find myself constantly starved for more. This has led me to do things I never in my wildest dreams dreamed of… and believe me my dreams were pretty wild!

Never along the way did I imagine I would spend countless summer nights driving the back roads of Tennessee peering through the eye-piece of a high-end piece of video equipment searching for wildlife. That piece of equipment wasn't just an expensive camera either, it was a handheld thermal imager. The kind of camera that sees heat instead of visible light. It was introduced to me in the summer of 2006 by Dale Grandstaff, an eager young wildlife officer in Montgomery County. 

Given the high-tech equipment to assist with law enforcement duties, Dale discovered something truly amazing. I distinctly remember sitting at my desk when Dale gave me a call and simply said, "Daryl, you have GOT to see this!" A few days later I was up in Montgomery County sitting in Dale's truck anxiously awaiting the sun to set.  In the meantime, he explained the camera as well as his excitement.

"As you look through the camera, the lens detects heat. Within the camera's field of view, it detects the ambient air temperature and then it assigns objects warmer than that temperature the brightest white, while the objects colder than that are assigned a deep black. Every object within the field that is close to ambient air temp is then assigned a shade of gray," he said eagerly.

I imagine my perplexed look told him I still didn't quite understand and had yet to share in his excitement.

"This is where it gets good," he said. "I took it out in the field the other night just to see what I could see....and I was absolutely blown away! You wouldn't believe the deer I saw!"

Dale then went on to explain why this camera was so special and the light bulb moment finally went on in my own head. Here's why...

In an urban environment, there are numerous artificial heat sources. Think about the thermal imagery you sometimes see on those law enforcement reality shows. You know, the ones where it depicts a "bad guy" running desperately through the streets in a seemingly hopeless situation. Oftentimes you see this glowing white human-like form running headlong down crowded streets all the while the "eyes in the sky" keep tabs on his every move. Think about it, he's pretty easy to follow with that camera. However, as you watch the video in your mind's eye, think about all the other glowing white objects in the picture. There are other people, street lights, car engines, various external motors such as A/C units and all sorts of artificial heat sources all around. All of these objects are drastically warmer than the ambient air temperature so they too glow bright white.

Now let's extricate ourselves from the city.

Let's think about a place in the country away from other people and machinery.

What in that landscape is the only thing that doesn't cool down when the sun sets?

Pro-Tech thermal imaging camera.

This is where high school biology kicks in. Geologic formations (I.e. rocks and dirt) along with vegetative matter (I.e. trees and other plants) all cool down with the dropping night-time temperatures; yet some things don't cool down. Yep, you guessed it...Animals! Specifically, warm-blooded mammals. Because of their bodily features and metabolism they are designed to maintain a constant body temperature somewhere in the mid to upper 90's.

If you were to look at a field of deer with a thermal imager on a mid-Summer's day, the screen would display a blurred vision of gray tones since all temperatures within the field of view would be hovering in the mid-90s.  Now if you wait about twelve hours until the sun sets and the ambient temperatures drop to the low 70s, or even better, 50's or 60's, the animals in the field of view will be "burnin' hot"...or in other words glowing bright white!

An elk tries to sneak past us in the pitch black night.

The animal's natural camouflage becomes obsolete and even their partially obscured or hidden bodies stand out. You could not only see all the mammals within your field of view, you couldn't miss them!

Needless to say, Dale's discovery led to multiple years of experimentation with thermal cameras for wildlife surveys. The cameras have been used for estimating deer and elk populations as well as for feral hog control. They have even been used to record the emergence of bats from their hibernacula.

Yeah...I have led a charmed life!