On Fri, 17 May 2013 11:57:10 -0300, Shadow wrote:

I had this issue with humming birds, decades ago, but only in
one room in the house. There were two large windows, facing each
other, at opposite sides of the room, so I suppose the glass was
invisible to them and they were trying tunnel through the room.

Humming birds are attracted to color. Perhaps they saw something
through the glass.

When my garage door is open I sometimes have one come inside; hovering
around the red emergency pull cord that hangs down.

Cool stuff