June 13, 2015

A Walk in the Woods

Here are some thermal observations from a walk in the Mulholland Wildflower Preserve in early June. First, some ducklings, cute even in infrared.

Mama mallard with a train of ducklings.

Continuing with waterfowl: a pair of common mergansers preening on rocks in the creek.

But take a closer look. In the thermal image (less magnified than the photograph), notice how the mergansers' breasts are cold, colder than the surroundings even! Presumably they have not been out of the water for too long. It's worth noting that because water reflects infrared, it's hard to gauge the temperature of the water from the thermal image.

Further down the trail, an eastern wood-pewee was singing its beautiful plaintive song, quite loudly, in fact, from somewhere above. This is a common scenario for woodland birding: you have this small brown bird sitting still somewhere high in the trees, and you just can't seem to find it. But with a thermal imager...

the warm body pops out from its cooler surroundings. Unfortunately, this only works on overcast days, for as soon as there is any amount of sunlight, the reflected IR from the sun makes many things (tree trunks and branches in particular) appear hot, and warm-blooded animals no longer stand out.

Nearby was this set of cavities in a sycamore tree:

I would like to conclude that the top cavity is occupied while the lower two are probably not, but I have no means to confirm this. I should write a blog post focused on cavities in the near future.

Finally, while walking down this dry creek bed, the high-magnification 35mm lens on my Therm-App showed this clear profile of a resting deer.

The deer was remarkably well camouflaged, such that I could never visually see it in its sitting position as shown in the thermal image, even with my binoculars. The deer did eventually walk away (they have little fear of humans in this area, and are actually quite the nuisance for plant life), and I still can't tell whether the deer is present or not in the visual photograph above.

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