Using "standard" 1.5 inch hole cutter to make openings deters House
Sparrows - I watched one trying with no success to get its shoulders
into an opening in an older box on the property... No need to make
strange shaped openings, though a Purple Martin house on the market
with half-round openings at floor seem a good idea, but very
expensive, unless you do it yourself! I've just put up a few
"half-gallon" sized plastic coffee cans, the new kind seen in stores
of late, and hope they work (and used one to replace an
"inside-the-shed-wall" cardboard "box" - I'd drilled hole in wall and
stapled cardboard box-shaped house inside - lid stapled to opening
spot makes it so I can remove the "can" for cleaning - VGSW used it
the past two summers, both times successfully). Pix on request for
any and all of what I describe - I haven't made pix of latest
recycling "invention" yet [also in past, I used 2-liter bottles that
chickadees like - in Virginia, but have seen Eastern bluebirds use as
well]... Hole can also be drilled in side of coffee can, and the
thing hung on a fence or under eave with lid up, for drainage if
exposed to rain; DRILL holes in the bottom! ... Entry should NOT be
more than 1.5-2 inches above floor, as someone noted swallows have
little or no ability to hop to it, and can be doomed ... I put small
twigs and crushed leaves inside each one for "footing"... I built a
swallow "condo" which has worked the past two summers - but it has
too many openings (8); only 3 and 2 sites used, respectively, ALL
successfully - Jim Greaves, Thompson Falls