How to find the needle in the haystack, that is if you've deployed it with a radio collar

I've always wanted to radio-track an animal, ever since seeing it on National Geographic or some other Discovery Channel program when I was a kid. We've all seen it, a scientist holding a huge antenna (or maybe it's mounted on the back of a truck), tracking tigers or mountain lions or bears - something big and ferocious (and far-ranging).

So when I took on my project, I was really excited to track my first flying squirrel. Luckily, the antennas are much smaller (because squirrels don't move nearly as far as larger mammals) and the larger the antenna, the further away it can detect a signal. Especially since we don't drive around in a truck, we hike through the forest to find the squirrel's tree.

Since I was interested in squirrel nest trees (and more specifically, the cavities they used), I would trap squirrels at night, attach a radio collar and let them go. Flying squirrels are nocturnal, which means they are active at night, so we would leave and come back in the day when they were asleep in their nests. That way I could find the cavities they used.

To find them, you just follow the beep. Whichever direction is the strongest sounding beep on your received is the direction they are in. Every now and then a rock face or hill can throw you off, but you soon discover your error as soon as you get to the top, and the reception is clearer. The trickiest part is when you get down to two or three trees that are close together. Squirrels tend to nest high in the trees, so it's not as simple as pointing the antenna at the tree at face height. You have to angle and twist and turn to make sure you have the right tree.

Looking for cavities always helps... if there are two trees, and one has several obvious cavities and the other has none, they are more likely in the one with the cavities. You still need to double check though. My favorite way is to hit the tree with a stick - if the cavity isn't really deep, a squirrel will poke its face out of the cavity to see what's hitting its tree (which doesn't seem like a great survival strategy I know). Years ago this was actually how biologists caught flying squirrels, by netting them out of their cavity holes (it seems like such a cowboy tactic - squirrel wrangling).

All in all, it's like playing hide and seek with such an advantage that the seeker always wins. And finding a squirrel's cavity is very satisfying (especially if you can get an impromptu glide out of a squirrel by banging on the tree)!