Strange behavior for a chickadee

I have far better pictures from my morning walk, but I want to tell you about a new bird behavior...new to me at least.

This morning I saw a chickadee land on this tree trunk and disappear. Thinking my eyes were playing tricks on me, I walked closer to see where it went. What I discovered was a small hole in the tree. The chickadee landed on the trunk next to this hole and cautiously checked out his/her surroundings. Eventually, after many aborted attempts, s/he popped into the hole and disappeared from sight. I waited. Several minutes later, s/ he flew out of the hole so fast that the photo I took only shows a blur of wings. I've never before witnessed this behavior in a chickadee. If anyone can give me an explanation, I would love to hear it. I stood several feet from the tree for about 1/2 hour and watched him (or her) repeat the behavior a few times. S/he never slipped into the hole without very carefully surveying the surrounding area. Apparently I wasn't a threat because I threw out a few peanut chips, and all of them were eaten.

It's Tuesday again, so I am blipping early because I will soon pick up my two-year-old friend at her daycare and spend the evening with her. Tuesday sure comes around in a hurry.

PS: If you are curious about the chickadees and want to see a few more photos from today's chickadee adventure, I have posted them here.