Today was cold windy and a bit of snow fell. I was able to make the last of the owl guards for my gourds. Since 2009 my colony declined from 79 active nests (a nest where at least one egg was laid) to last years 36 active nests. I attribute the decline to disruption and predation by the resident great horned owls.
Until last year I took no additional measures against the Owls other than providing large gourds, double size compartments and starling resistant entry holes, which are speculative as far as owl protection, but I do feel they make it a bit harder for owls to reach into compartments.
For this year I am completely overhauling the colony and owl guards of some sort are a part of all of the 129 compartments I am offering for my martins. I am optimistic the measures taken will get my colony back to its former numbers and then some. I will keep you posted as to the progress.