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2008 2012  Wisconsin (Kastner) Test Site

Shari Kastner of New Berlin, Wisconsin was having problems with both House Sparrows (HOSP) and House Wrens.  House Sparrows had killed an adult female bluebird in a 1-holed box the year prior to the test.  A "House Sparrow Resistant" Gilwood nestbox (see photo) was at the site during early 2008, along with trapping, and House Sparrow problems continued.

This is the type of situation that best illustrates the effectiveness of 2-holed boxes. Since these tests are to assess box performance outcomes between HOSP and bluebirds, there can be no monitor interference other than removing HOSP nests during box checks.  That includes no trapping and no addition of HOSP-deterrents (spookers, halos)

She agreed to set up a 2-Holed Box performance test for three years and began the test as of 4/19/08. 


Synopsis of the 3-Year test & Beyond:
  • There was intense HOSP/bluebird competition during the first two years of the test (a lingering problem from the previous 1-holer)
  • 2008 First Test Year: Bluebird eggs cracked (assumed by wrens)
  • 2009 Second Test Year:  Bluebirds fledged the second year.
  • 2010 Third Test Year:  No HOSP nests the third year, but wrens persisted

End of 3-year test but Shari continued test site conditions and reporting:

  • 2011 Fourth Year:  House Sparrows & Wrens only
  • 2012 Fifth Year:   House Sparrow nest (no eggs) then Tree Swallows fledged and then Bluebirds fledged

See Test Logs and Notes Below:

Logs begin on 4/2/08 with Bluebirds and House Sparrows competing for a 1-holed Gilwood box.  Shari traps House Sparrows out of the Gilwood.  That doesn't solve the problem and she installs the test 2-holer on 4/19/08 and agrees not to trap from that point on.

First Year



LOGS / Observations


Monitor Action
  Gilwood 1-holer in place before the test begins  
4/2/08 2 Bluebirds by Gilwood box w/HOSP nest Male HOSP trapped
4/6/08 HOSP nest in Gilwood 1-holer Removed nest, trapped HOSP
4/13/08 -0-  
4/16/08 HOSP flew out of Gilwood (no nest)  
4/19/08 -0- Changed to a 2-holed box
4/27/08 -0-  
4/29/08 Leaf in box  
5/3/08 HOSP nest?  
5/13/08 HOSP nest & eggs  
5/15/08 HOSP nest & eggs, Male HOSP on 2-holer Removed nest & eggs
5/19/08 -0-  
5/21/08 House Wren Sticks Emptied
5/25/08 House Wren Sticks Emptied
6/1/08 House Wren Sticks Emptied
6/8/08 -0-, HOSP on 2-holer  
6/15/08 Few Wren Sticks  
7/3/08 4 EABL eggs, fem on  
7/11/08 2 EABL eggs, one cracked open Removed top part of nest
7/17/08 No change  
8/18/08 No change Emptied
Linda's comment: Loss of eggs during the first "Transition" Year sometimes occurs at difficult locations while bluebirds gain confidence defending the box  

During the second year of the test, bluebirds outcompeted House Sparrows, defended the box from House Wrens and fledge four chicks.   I believe this represents the first bluebirds to fledge from the location.

Second Year (2009) at this test site was successful

Second Year



LOGS / Observations


Monitor Action
2nd Year (2009)

Logs (observation)

Monitor Action
  2-Holed Box in place from the start of season  
3/26/09 HOSP on nest when door opened  
4/2/09 HOSP flew out of box, BB pair near box Removed HOSP nest
4/19/09 HOSP nest & egg Removed nest & egg
4/26/09 HOSP nest Removed nest
5/3/09 HOSP nest & 5 eggs Removed nests & eggs
5/10/09 HOSP nest & 2 eggs Removed nest & eggs
5/16/09 Wren Sticks Removed Wren Sticks
5/28/09 Wren Sticks Removed Wren Sticks
6/9/09 HOSP (2) exited box upon arrival Removed HOSP nest start
6/17/09 4 HOSP eggs Removed HOSP nests & eggs
6/26/09 EABL fem building nest (almost complete)  
7/7/09 4 EABL eggs, fem flew off  
7/8/09 4 EABL eggs, pair on box  
7/11/09 4 EABL eggs, pair on box  
7/14/09 4 EABL eggs, pair on box  
7/17/09 4 EABL chicks, fem flew off  
7/25/09 4 EABL chicks doing fine  
7/30/09 4 EABL chicks looking huge  
8/4/09 4 EABL chicks fledged  
Linda's comment: Thanks, Shari, for providing this test site.  

This was an especially complex test site because House WRENS were just as much of a problem as House Sparrows.  During the third test year, the test box was free of House Sparrow problems.   Wrens, however, were persistent and there were no nest attempts by bluebirds.

Third Year



LOGS / Observations


Monitor Action
Date 2-Holed Box in place from the start of season  
March 2010 No Activity Reported  
Early April Few strands of grass  
4/17/10 Few strands of grass  
4/21/10 Male HOSP flew out of box  
4/22/10 Small amount of grass and feathers (no ID) Removed all
4/26/10 Nest start (no ID) Removed all
May 2010 Nest (no ID) slowly being built  
5/26 to 6/2 Wren Sticks on top during multiple checks Removed sticks
6/10 Wren Sticks (Huge nest) Removed all
June 2010 Wren Sticks Continual removal of wren sticks
7/10/10 Wren Sticks Removed sticks



Fourth Year



LOGS / Observations


Monitor Action
Date 2-Holed Box in place from the start of season  
4/6/11 -0- (no activity)  
4/10/11 -0- (no activity)  
4/19/11 Few dried grasses w/seeds (HOSP?)  
5/3/11 HOSP nest - no eggs  
5/10/11 HOSP nest - no eggs  
5/24/11 Mystery Nest  
6/2/11 Mixture of HOWR, HOSP, maybe EABL Removed mixture
6/13/11 HOWR Sticks Removed
6/16/11 3 Wren Sticks  
6/28/11 Wren Sticks Removed sticks


Fifth Year



LOGS / Observations


Monitor Action
Date 2-Holed Box in place from the start of season  
4/17/12 Flower stalks and thicker stuff Removed
5/3/12 HOSP nest - no eggs Removed
5/11/12 TRES nest & pair  
  Linda's (box designer) Note:

I do NOT have any experience as to Tree Swallow battles with House Sparrows.   I'd recommend trying a "Spooker" or Magic Halo as a HOSP deterrent but there are reports that Tree Swallows may or may not accept certain Spooker designs.

Shari (the monitor/tester) decided not to intervene with a spooker.  Thank you, Shari, for continuing the no-trap and no-gadget conditions (see excellent results below).
5/23/2012 4 TRES eggs -0-
6/5/12 TRES eggs -0-
6/20/12 TRES babies looking good -0-
6/24/12 TRES babies looking out the hole(s), so cute! -0-
6/26/12 TRES Fledged!  Removed nest
7/10/12 New nest, grasses, feathers, needles  
7/26/12 4 Bluebird Eggs  
8/2/12 4 Baby Bluebirds  
8/30/12 4 Bluebirds Fledged  


Here are weekly logs showing transition from 1-holers to 2-holers at problem sites on my own trail here in Yorba Linda, California:   2001 Golf Course Logs.

There is usually a 3-year pattern to turn around a HOSP/bluebird problem site:


Here is the Construction link showing how to build these boxes.





As of June 15, 2012