Jack Schmidling wrote:

Whenever were hear crows, jays and even chickadees raising a ruckus this
time of year, we need look no farther than the Wood Duck nesting box.


If I was to put up a box like that in my yard it would be taken over by
squirrels within days and no bird would have a chance against them. I put
up a dozen hexagonal and octagonal boxes of my own design -- cedar wood and
copper-covered roofs. Almost immediately I found the squirrels remodeling
them to make the openings large enough to enter. I tried covering the
fronts with polycarbonate shields with appropriate sized holes over the
originals figuring that even squirrel incisors couldn't chew bulletproof
plastic but in a couple of cases they just chewed their way in from the
side. For now I've given up, at least until I can figure a way to weld up
bird boxes from steel plate.

--
John McGaw
[Knoxville, TN, USA]
http://johnmcgaw.com