That guy is spewing overly dramatic BS. It's not canine at all in the dentation and skull shape, it's clearly Opossum! Look at this example:
I haven’t read it but this book seems to be very well reviewed
Bird Tracks & Sign : A Guide to North American Species https://www.amazon.com/dp/0811726967/ref=cm_sw_r_cp_api_glc_fabc_Hlt3Fb1325JC7
Did you check the inside of the cup for poop? 🤢
You can also get a black light for cheap and any urine will glow fluorescent. Escolite UV Flashlight Black Light, 51 LED 395 nM Ultraviolet Blacklight Detector for Dog Urine, Pet Stains and Bed Bug https://www.amazon.com/dp/B008133KB4/ref=cm_sw_r_cp_api_i_YZ46Y96R8VGEG5P8JH7M?_encoding=UTF8&psc=1
Very cool! Thanks for sharing!
A while back I read a book about wildlife safari work and they had interesting stories of how honey badgers would wander into camp. You had to let them. 🤪
Whatever You Do, Don't Run: True Tales Of A Botswana Safari Guide https://www.amazon.com/dp/0762796472/ref=cm_sw_r_cp_api_glt_i_XMCT327TPMV5B9V1MR41
Feline tracks. Bobcat most likely. Odds are incredibly low for it to be mountain lion. They are no longer in the area, but one may pass through every decade or two. Sadly, you likely would have already heard about it in the news or in town if it was actually a real mountain lion. With all the security and trail cameras out now, it’s hard to pass by undetected.
This book is fantastic and discusses a mountain lion that did actually make it to the east coast. There were numerous sightings, tracks, etc before it was hit by a car.
Ghostwalker: Tracking a Mountain Lion's Soul Through Science and Story https://www.amazon.com/dp/0692163859/ref=cm_sw_r_cp_api_glt_i_8FJH0K2P111M0C2V5V62
That book is animal tracks and scat of California by mark elbroch. Mark elbroch is probably the biggest name in tracking in the US. I’d recommend another book of his though, which is this one:
The California one is just a condensed version of this one. Slightly smaller and less info
Good questions. I don't know what the canonical text would be for animal tracking; I started with Tom Brown's Field Guide to Nature Observation and Tracking, buuuuut... I sort of hesitate to recommend it because along with the good stuff there's also a lot of stuff in there that's total nonsense.
Dirt time is super important. You can learn all the terminology but it takes a lot of hours of field practice to recognize more subtle sign.
Gear-wise, the following are all recommended items for man tracking and should cross over to animal tracking pretty well:
A seamstress' tape measure, I've been happy with these, although I stopped buying things from Amazon years ago so maybe these are garbage now too.
Wooden kebab sticks from the grocery store. Paint one end of them with something bright that will be visible in mixed terrain.
A really good flashlight. Opinions on the ideal light for tracking varies a lot from individual to individual. I prefer a compact white light with a tight beam and a long throw that's bright enough that I can use it on an overcast day if necessary. Start cheap so you can try different color ranges and beam types. But, in general, avoid anything that blinks.
A hat and a mirror. In bright overhead conditions you can highlight a patch of ground with a hat and mirror and get tracks to show up that you wouldn't be able to see otherwise. Takes a little practice.
So many other things are gonna come down to the specific approach you'll use for tracking, like whether you spend more time trailing on the ground or more time cutting.