Timmy fell in the well?

Sometimes I wish we had as sensitive of a nose and ears as our four-legged friends (dogs). Today, Belle got my intention to go outside (which she doesn't even do to when she needs to go to the bathroom!), managed to convince me to go down the deck stairs, and attempted to point out something to me by this tree in our backyard.

Click to enlarge and see Belle's cycle of curiosity

I have no idea what she saw, but after watching her do the above pictured cycle of going to the sidewalk and staring up, walking down to the tree and jumping on it for over 20 minutes, I KNEW she sensed something.

Click to enlarge and see Belle's cycle of curiosity

Sequoia wasn't nearly interested (that's the real surprising piece), but they both were intently sniffing the base of the tree. Almost as of some other animal marked its spot there.

It bothers me a bit that I can't find what they so obviously smell or hear. [For those of you who know Belle well know that its very out of character for her to cry and jump at a tree].

Hmmm... guess I'll never know!