House Sparrow Test Site in Connecticut 

Bet Zimmerman (NABS Board of Directors)of Connecticut agreed to set up a no-trap test site for a period of three years and according to the Keys to Success.  That was not done. 


Alternate Trapping Site:

Bet Zimmerman is a STRONG supporter of trapping House Sparrows and an expert trapper.  Shortly after she hung 2-holers at this no-trap site, she set up an alternate TRAPPING site at Taylor Brooke Winery using about nine nestboxes, some HOSP resistant (slots, etc.) with add-ons (spookers and monofilament to deter HOSP).  Only the slot box fledged bluebirds during the first year of trapping. No bluebirds fledged the second year of trapping.  And only one clutch of bluebirds fledged the third year.  Links to her trapping site are provided at the end of this page.


This no-trap site using 2-holed boxes was intended to span a period of three years to assess performance of 2-holed boxes in areas with a history of intense House Sparrow competition.

Unfortunately, by the second year of the test, there were more 1-holers at the site than 2-holers.  Then the site was essentially a test of how well House Sparrow Spookers performed on standard 1-holed boxes.   The benefits of adding Spookers to nestboxes to deter House Sparrows was impressive. 


Performance data of 1-holers without Spookers compared to 2-holers can be viewed at a different test site at:    2-holed results vs. 1-holers


Correct Spacing is Critical to Outcomes:  Doubling up boxes in a Bluebird territory does not result in twice the number of Bluebirds fledged from a site.  It results in Bluebirds not being able to defend multiple boxes from House Sparrows.  And bluebirds have a tendency to abandon contested boxes in favor of a nearby uncontested box.

Bet's logs state: "Measured distance between boxes, approximately 300 feet except for 150 feet between H-12 to H-10 and H-11 to H-10. Box 6X is 50 feet from H-10, 200 feet from H-9." 

Translation:   Every box has some other box within 300 feet.  Standard spacing for Bluebird boxes is 300 feet from one another to allow a forage territory of about two acres per box.  A 2-holed test box was placed only fifty feet from a 1-holed homeowner box (6x on Bet's map) where House Sparrows had been allowed to nest prior to the test.  Large 2-holers are shown on the map with red squares.  Smaller 1-holed boxes end with an "x". 


EXTRA BOXES:   In addition to the boxes shown on the map,  someone re-opened six old 1-holers amongst the 2-holers. 


AND someone installed a colorful collection of 1-holed boxes next to the test site (see photo). 


Bet Zimmerman's notes on what happened at this location can be read at:

Bet's conclusions can be viewed at:


2-Holed Test Results:   As far as HOSP/bluebird competition in 2-holers, the test was a success.  Bluebirds held the nestbox and fledged from a 2-holer with intense HOSP competition at the box, and in surrounding boxes. 

Any 1-holed boxes at these tough test sites are at the monitor's own risk.  Monitors can expect deaths to occur in 1-holers.


The information in the table below was taken from Bet's log notes (links above)  but not worth taking a LOT of time to study because test 2-holers are not to be placed in close proximity to 1-holed boxes, or to one another, as was done here.  It does, however, provide a snapshot overview of HOSP movements/activity throughout the boxes during the season.  It also shows that bluebirds could fledge chicks from 2-holed boxes, amongst intense HOSP competition and without trapping.




200 feet from the 1-Holed Nestbox

Homeowner 1-Holer

50 feet from H-10 and 200 feet from H-9




50 Feet from 1-Holer and 150 Feet from  H-12



150 Feet from H-10



150 Feet from H-10

Winter (Jan-07) Acorns ? -0- -0- -0-
3/11/07 1/2" HOSP nesting material (left as-is to verify) HOSP nesting material removed Acorn Shells Acorn Shells Male Bluebird in tree
3/16/07 3" HOSP nest material (left as-is to verify) 3" HOSP (left as-is) -0- -0- -0-
3/24/07 Completed HOSP nest with lots of grape vines (left as-is to verify) HOSP pair flying away from box. Nest removed. Acorn Shells

Bluebird pair in tree

-0- -0-
4/5 & 4/7 HOSP Nest Removed (no eggs) Male in Box  

HOSP Nest Removed 


-0-, little grass

Bet saw box on very low limb during a drive-by & stopped to rehang

HOSP Nest/no eggs (assumed removed)

-0-, little grass
4/13/07 Some HOSP material removed Little grass removed Some shells (acorn) Box hung higher Lifter broke, no check
4/22/07 1" Nesting Material left as-is to verify Little HOSP material  removed -0- Same nest material left as-is to verify -0-
4/28/07 HOSP nest (no eggs) removed 1" HOSP material removed -0- Tufted Titmouse (seen)  building nest. 

Hole Reducer to protect TUTI  Recommended but wasn't added.


Grass & Moss
5/3/07 HOSP nest (no eggs) removed 1/2 HOSP nest (no eggs) removed -0- Tufted Titmouse still building nest  HOSP material over moss; left as-is
5/6/07 HOSP nest (1 egg) removed 1/3 HOSP Nest; Added 1.25" thin metal hole reducer to deter HOSP at 1-holer. -0- TUTI nest (no nestcup)  HOSP? nest (left as-is to confirm)
5/8/07 HOSP nest (no eggs) removed One piece of grass removed.  -0- TUTI nest (no nestcup)  HOSP? nest (left as-is to confirm)
5/15 & 5/16 HOSP nest & 4 eggs removed  Wren sticks TUTI nest (no eggs). 1&1/4" Thin Wooden Hole reducers added.  HOSP nest & 1 egg (removed) HOSP nest & 1 egg (removed)
5/19/07 -0-

Moved box a few trees further north

 HOSP  3 eggs (removed) TUTI nest (no eggs).  HOSP nest & 2 eggs (removed) -0-
5/26/07 -0- HOSP nest & 2 eggs (removed) HOWR sticks over TUTI nest HOWR sticks, removed all and found 2 old TUTI eggs under nest HOSP nest (no eggs) removed
6/2/07 Several inches fresh green leaves (left as-is) HOSP Nest (no eggs) removed HOSP Nest (no eggs) over old TUTI base.  HOSP portion removed. -0- HOSP nest, 5 eggs  removed
6/9/07 Flying Squirrel came out of box HOSP Nest & 5 eggs removed No change Few grass pieces -0-
6/16/07 Just leaves 1" HOSP material removed Removed old TUTI nest base & hole reducer -0- -0-
6/22/07 Chunks of grass w/leaves 2 HOSP eggs/nest removed -0- 1" HOSP material removed -0-
6/30/07 -0- 1/4" HOSP/egg removed (male on roof) -0- -0- EABL tall nest & 1 egg
7/6/07 -0- HOSP Nest (no eggs) -0- -0- 3 EABL eggs (incubating)
7/14/07 More grass w/tunnel; Flying Squirrel inside 5 HOSP eggs oiled by monitor "to avoid harassment of Bluebird nest" -0- -0- 3 EABL eggs (incubating)
7/21 & 7/22 Not Disturbed Oiled eggs gone, bigger nest (removed) -0- -0- 2 EABL chicks
7/28 & 7/29 No Squirrel seen -0- -0- -0- 2 EABL chicks, only female adult seen (single?)
8/5/07 -0- -0- -0- -0- EABL Fledged
Total 2007 5 HOSP Eggs (2-holed) 
18 HOSP Eggs (1-holed post-mounted box) 
No HOSP Eggs (2-holed) 3 HOSP Eggs (2-holed box) 6 HOSP Eggs (2-holed box)
End of 2007 Data

Data after 2007 is not tracked because there was no further Bluebird/HOSP activity in the test boxes.

Below is a photo of Bluebird chicks found dead on the ground below a 1-holed box protected with a "Spooker" at this test site.   See 

Bet thinks the bluebird chicks were killed by House Sparrows.  The markings on the chicks look similar to what I saw on my trail when Starlings were pulling Bluebirds out of boxes that weren't deep enough.   House Sparrows don't typically pull chicks out of nestboxes.  Either way, the bluebird deaths occurred at standard 1-holed box with Spooker.

No Bluebirds were usurped or killed by House Sparrows in the 2-holed boxes.



TRAPPING:  These boxes can be used in conjunction with trapping.  At test sites, however, no trapping is permitted because the purpose of test boxes is to record performance of the box (not trapping skills or effectiveness of Spookers).


As mentioned at the start of this page, Bet is a STRONG supporter of the need to trap.  Her extensive collection of House Sparrow control methods are at:  Managing House Sparrows  Yet, Very few bluebirds fledged at her trapping site over a three-year period (links below will get you to Bet's trapping logs at Taylor Brooke's Winery):

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    More HOSP trapped.  Only a Gilwood (2.25" wide mouse hole) fledged bluebirds. 

No bluebirds fledged from any standard single round hole during the 3-year test period (through May 2010 when her logs stop).  Slot boxes with their wide entry may work the same as 2-holers.




As of June 15, 2012