Tweeters,

Anyone who knows a valid reason why the entry hole should or has to be 1 1/2
inch and 1 9/16 inch diameter instead of the eastern style 1 3/8 inches wide
by 2 1/8 inches high, please reply..I know the basic 1 1/2 inch entry hole is
primarily to keep starlings out...

I have noticed that most Eastern bluebird box plans show the entry hole to be
two 1 3/8 inch holes drilled on 7/8 inch vertically separated centers making
an entry hole 1 3/8 wide by 2 1/8 inches high.. Western plans generally show
a round entry hole of 1 1/2 or 1 9/16 depending on if mountain blues are in
the area..

I currently monitor fifty plus BB boxes on the North Wenas road, in Yakima
County. It seems like the boxes with slightly enlarged holes are preferred as
they seem to be the first boxes to be occupied and most often used...
Usually the entry holes in these boxes have been slightly enlarged by
woodpeckers, even though they have the typical aluminum or plastic guard
plate.. By larger I mean just opened up in random patterns, so that they are
simply easier to get in and out of..

When I replace one of these older tattered boxes that have slightly enlarged
holes with new boxes and standard sized entry holes, the occupancy seems to
drop about 50%.. I suspect that might be because the entry hole in the older
boxes is easier to get in and out, considering the number of times they do
this.

Plan to do an experiment this year by replacing 10 boxes with eastern syle
entry holes.. I assume someone here in the West has already tried this and
if so please post results..

Donald Peterson
Yakima WA