On Monday, I asked:

When we cleaned out the Wood Duck boxes last month, we noticed this weird oval depression around one of the boxes. (The ice within the oval seemed thinner....)

Anyone have any idea what might have caused it?

Three theories so far:

Neil MacLennan wrote: "My sense is that it was caused by the specific placement of the box and the prevailing winter wind direction. The prevailing wind comes from the NW and the post's position creates ripples starting in the NW that make it more difficult to freeze in the SE direction."

Julie McCall wrote: "my best guess is that the sun on the box and pole generated enough heat to cause some melt, and perhaps the breeze generated some drift of the slightly warmer area, and then some refreeze happened. just a guess, based on watching how snowmelt is occurring around objects (e.g. my outdoor plant pots, fire hydrants, shrubs, a leaf on the snow, etc.)"

I theorized: "Maybe someone started a small fire on the ice... Or the Ghosts of Allendale?'

What do you think?