Where flying squirrels go to count sheep...

I tracked squirrels to find their nest cavities, which I then measured (eg. volume, the direction the opening faces, opening area). Flying squirrels are secondary cavity nesters, which means they use cavities excavated by another species, such as a woodpecker.

A regular cavity looks like the one on the right. If you're lucky, once you track a squirrel to its tree you can hit the tree with a stick and a squirrel will either stick its head out of the cavity or actually run out and up the tree. If you're REALLY lucky, you may even get a glide right out of the cavity to another tree. That's always fun to see :) If you look really closely, you can see the nose of a squirrel towards the bottom of the cavity circle.

But then sometimes northerns shrug convention and do this to me. It's not new news that flying squirrels build leaf nests. It was just a little unexpected given the cold winter temperatures. Southerns do not even build leaf nests this far north. So when I stumbled upon my first nest, I thought it would likely be an outlier. But then I found more and more leaf nests...

So that brings us to this winter. This winter I collected several known leaf nests from last winter and deployed them with temperature loggers to look at the difference between outside (ambient) temperature and temperature inside the nests.

So far analysis of that temperature information shows that leaf nests are likely equivalent to tree cavities for buffering capacity. Stay tuned for more rigorous comparisons soon.

Winter gear: Just mush

The field site where I measured cavity temperatures was at a research property owned by Trent University. It is an old farm property complete with mature sugar maple forest. There is a gate and dirt road in the summer, but in the winter this gets snowed in, so you have to walk into (and around) the property.

To set up temperature loggers in the cavities I outfitted them with microchip detectors (to detect any flying squirrels that went into the cavity) and used a "treetop peeper" (camera on an extension pole) to check the cavities for any other small creatures that could be using them. This was to make sure the cavities were empty when I recorded temperatures, so that I was getting the insulating effect of the wood, not any heating effects of animals sitting on my temperature logger.

The microchip detectors had to be attached to large batteries, and the treetop peeper was stored in a large waterproof case, so getting gear in and out of the site was no easy task. Instead of carrying it all, the PhD student had the brilliant idea of taking a snowmobile sled, loading it with the gear and attaching the tree lanyard as a harness. Now getting all the gear in and out was a breeze... unless the snow was wet and sticky, which in that case it was still pretty difficult to pull the sled. BUT once you broke a trail, it was smooth sailing all the way back out.

Not to mention my legs were in excellent shape by the end of the winter!

Learning to climb

My research requires both inserting temperature loggers
into cavities and measuring the internal dimensions of cavities. Many of these cavities are out of a ladder's reach, which means we have to climb trees to measure them.

Yes, climb - not the free-climbing of your childhood, when you had not yet realized your own mortailty. This is the safety equipment riddled, muscle aching, uncomfortable climbing of adulthood - complete with spurs, harness, lanyards, helmet and rope.

I was taught to climb by two male students in my lab. Now I am dedicated to equality of the sexes, especially being a female graduate researcher and all, but they just make it look easy. The upper body strength of a rugby player versus my upper body strength (where my workout is carrying groceries home from the store) does not even compare. It's hard work, and I'm glad I did it in the winter (when you can never get too warm and there are no biting flies!).

That aside, it's pretty fun! And getting that high in a tree
offers a great view of the surrounding countryside! Once
you get comfortable and lean back, it's actually quite relaxing
(until you have to start climbing back down).

The scariest part is if you lose your footing. The lanyard and harness are there to slow your fall out of the tree, and turn it into more of a slide, but a very uncomfortable one at that. I know a person with scars going up his stomach from sliding down a large portion of a tree with the lanyard and harness attached.

You try your hardest to get a good footing, and stick the spurs in deep. There's no kicking involved, just stepping straight down on them and letting your body weight do the work. But every now and then a piece of tree flakes off (the piece with your spur in it) or the tree is just too frozen/hard to get your spurs in very deep. That's often when you slip. It's not that I'm afraid of heights, but I certainly am afraid of falling. There were a couple of times last winter that my spur slipped and my heart skipped a couple of beats (and it kinda felt like it left my chest and made a new home in my throat).

All in all, climbing is an interesting and challenging skill to have, and I am glad I learned it. Will I climb just for fun? Probably not... I still get the rugby player to climb "tough" trees for me :)