Male Western Bluebird
Yorba Linda, Calif. (10/13/01)
This trail in Yorba Linda, California fledges hundreds of Western Bluebirds each nesting season. Quite a few nestboxes are situated in difficult environments with House Sparrow problems. This web page is dedicated to other Bluebirders who are working under similar conditions and need to provide their Bluebirds with more defensible nestboxes.
Much of today's information on House Sparrow control is based on yesterday's viewpoint that you have to spend time aggressively trapping House Sparrows OR use substandard nestboxes that House Sparrows will avoid. There are other alternatives. Western Bluebirds are successful on this urban southern California trail without the need to trap or kill House Sparrows.
By using 2-holed boxes, adult Bluebirds can survive an attack and successfully outcompete House Sparrows. Box plans are provided in the link above for anyone wanting to build this box. Since fewer people are building their own boxes, anyone wanting to purchase one of my used boxes after the season (no profit to me), may contact me at: Linda Violett .
Two-Holed Box Performance Tests (no trapping)
Links of 2-holed box test sites are provided below. I believe these are the only tests of their kind where a box designer has segregated box performance by placing boxes where there are known HOSP/Bluebird battles and not use any gadgets (spookers) or trapping.
These tests show how the BOX performs, not how well the monitor can trap out House Sparrows. If anyone knows of any similar tests on other box designs, please provide that information and I will add those links to this web page.
Successful test sites were those having only one Bluebird box per two acres forage and where House Sparrow nests and eggs were removed promptly each week. Large trail monitors should expect a few Bluebird losses during the first "transition" year at difficult sites as Bluebirds learn to use the escape hole. There are usually little to no House Sparrow problems during the second year as bluebirds gain confidence defending the box and by the third year, the bluebirds should be in complete control of the box. The best test site to study is the one set up by Shari Kastner of New Berlin, Wisconsin. It involves only one box, is easy to follow and is an example of a site with both House Sparrow and House Wren problems.
2-Holed Box
No-Trap Test Sites:
2008 — 2010 Wisconsin/Kastner (one box)
NEW: 2010 — 2012 Virginia (one box)
(well spaced) (Box Size Test)
2007 Tests - Bet Zimmerman — No-trap 2-holed test site was not set up properly. It ended up being a test site for 1-holed boxes using House Sparrow Spookers.
Trapper's Logs — About NINE boxes (mostly 1-holed boxes)
Bet Zimmerman is in the process of trying to turn around a
HOSP-infested site at Taylor Brooke Winery. Logs (links
below) show various layers of House Sparrow control being used.
Bet is actively trapping House Sparrows, pairing boxes for Tree
Swallow protection, using "House Sparrow Resistant" boxes (slot
and Gilwood), adding spookers and monofilament on top of the
boxes, and is removing House Sparrow nests and egg.
In spite of these efforts, no bluebirds fledged from any of the 1-holed
boxes during the first two years (2008 and 2009). A slot box fledged bluebirds in 2008 but it was taken over by
HOSP in 2009. No bluebirds fledged from any of the boxes
the following 2009 year.
2008 trapper's logs
—— 27 HOSP trapped; only the slot box fledges bluebirds
2009 trapper's logs
—— 7 HOSP trapped, no bluebirds fledge from any boxes
2010 trapper's logs
—— pending results
For those who rely on trapping House Sparrows, the job never
ends, the job is never complete and results are sporadic. Note to homeowners who
feed house sparrows: Here is a
link showing what some Bluebird monitors have to go through to catch House Sparrows:
Trapping
In our southern California urban area, most monitors just remove boxes where
House Sparrows have taken over areas. House Sparrow problems are
usually a result of homeowners feeding and raising House Sparrows. If you feel you must feed birds, at least be selective and limit your
offerings to Hummingbirds/nectar; Safflower (not sunflower) for Finches/Doves;
Thistle for Finches/Siskins. Those choices are the least damaging to our
environment.
*
Trail management is just as important as nestbox design.
Sparrows are not allowed to use nestboxes on this trail and they are never
allowed to sit on eggs or young. Bluebirds need two acres forage to
find insects. Boxes should be spaced at least 300 feet apart for
consistent results. Initially, boxes were not being built deep enough to protect
nestlings from Starlings reaching into the box. Deeper boxes (8"
hole to floor drop) with wooden face guards solved the starling problem.
See Box Depth link above.
Some "House Sparrow Resistant" boxes are promoted with a profit in
mind. If House Sparrows actually avoid a nestbox, there is a reason.
You should be asking questions before purchasing any so-called "House Sparrow
Resistant" box and asking for performance logs of test sites.
Hanging Nestboxes
Be sure to look at: How to Add Hangers and placement tips.
You may contact me,
Linda Violett
