After comparing my scat shots to those on other sites (here, here, and here), it appears that a black bear is wandering around my neighborhood late at night. While this is uncommon for this time of year, when bears are usually hibernating, a neighbor tells me that a few years back a 289 lb black bear walked right up to his back door, silencing his guard dog with one snort. The bear was shot with a tranquilizer and released back into the wild. Apparently it was then shot and killed out of season when it turned up in Cornwall. So it goes...
In any case, we're taking all the necessary precautions. Thanks for JoeMelzingah for the following advice:
"A little shouting and arm waving will shoo them away, or give them a squirt on the nose with a CO2 fire extinquisher if they're close by - the cold blast will discourage them without doing any harm."
I'm also teaching myself this useful little ditty, "Hey Bear, Are You There?", to sing with my kids. Hopefully it will help get them used to the idea that there may be bears lurking in the yard. It'l also come in handy when we're hiking. Again, thanks to everyone for helping me figure this out. While I'm still not 100% sure (I guess it could be a coyote or bobcat), I now know more than I ever thought I would about bear scat. Happy New Year!!