2-Holed Mansion Test Site in Connecticut
Bet Zimmerman of Connecticut agreed to set up a test site according to "Keys to Success" http://home.earthlink.net/~lviolett/keys.html. The intent of the test was to see whether Eastern Bluebirds could outcompete House Sparrows, without trapping, by using 2-holed boxes.
Bet is a NABS Board Member, author of Sialis.org and is a strong supporter of the need to trap and kill House Sparrows.
Test site setups are simple:1) Provide a 2-holerTheory: Bluebirds can outcompete House Sparrows (HOSP) if they can escape and take the battle outside the box.2) Place the box within two acres of forageTheory: The safety of the box in HOSP areas depends on Bluebirds defending the box 24/7. If there is insufficient forage, Bluebirds have to leave the box undefended to find food.3) Do not add any other Bluebird-sized box within the territoryTheory: Behavioral tendency of Bluebirds is to avoid a conflict. They sometimes abandon a box and move to an uncontested box. But if only one box is available, they will fight for it and succeed.4) No Spookers, trapping or gadgets.Theory: Results of the escape hole have to stand on their own merits. The only monitor action required is weekly removal of HOSP eggs/nests. In our area, HOSP are ready to nest earlier than Bluebirds. The presence of an early HOSP nest does not signal a battle took place.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. House Sparrows have a much greater opportunity to come in and cause problems. Bluebirds have a tendency to abandon contested boxes in favor of a nearby vacant box.
One of the 2-holers was placed only fifty feet from a 1-holed homeowner 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 and a 2-holer (H10) was placed only 50 feet away from a 1-holed box where homeowners have allowed House Sparrows to nest. Standard spacing for Bluebird boxes is 300 feet from one another to allow a territory of two acres per box.
EXTRA BOXES: In 2008, someone re-opened six 1-holers amongst the 2-holers (not included in the photos). From that point on, there were more 1-holers at the site than 2-holers. Boxes with one hole are too dangerous in areas with House Sparrow infestations. Bet added spookers and monofilament to the 1-holed boxes. However, Bluebird losses still occurred in the 1-holers. (see http://www.sialis.org:80/picturehospkill.htm). Poor results of 1-holers are mixed into the "Conclusions". There were no Bluebird losses in 2-holers.
Bet Zimmerman's notes at http://www.sialis.org/trailhilllog2007.htm. were used to create a side-by-side visual table (below) for an overall look at the first year activity in all the boxes before the test site was inundated with 1-holed boxes the following 2008 test year.
DATE
H-9
(2-Holer)
200 feet from the 1-Holed Nestbox
Homeowner 1-Holer 50 feet from H-10 and 200 feet from H-9
H-10
(2-Holer)
50 Feet from 1-Holer and 150 Feet from H-12
H-11
(2-Holer)
150 Feet from H-10
H-12
(2-Holer)
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) 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 were no Bluebird/HOSP battles at 2-holed boxes after all the 1-holed boxes were opened amongst the 2-holed boxes in 2008.
Eastern Bluebirds successfully fledged chicks during the first test year (2007) from a 2-holer amongst heavy House Sparrow activity without the monitor having to trap and without using gadgets such as spookers or monofilament. The test, as far as Bluebirds being able to outcompete House Sparrows in 2-holed boxes was successful.
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 http://www.sialis.org:80/picturehospkill.htm).
Bet thinks the 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 loss was caused at a standard 1-holed box.
No Bluebirds were usurped or killed by House Sparrows in the 2-holed boxes.
Bet and her husband, Doug (pictured) preferred using a ladder rather than a pole to lift boxes into the tree.
Box Height and House Sparrows: An interesting observation from the 2007 data is that House Sparrows laid more eggs in the (lower) post-mounted 1-holed box than in any of the hanging 2-holed mansions.
Following is an excerpt from Bet's web site http://www.sialis.org/hosp.htm regarding House Sparrow control
"If a HOSP shows an interest in a box that bluebirds have claimed, immediately lower the height (temporarily) of the bluebird house to about 4 feet. Put up another house a few feet away at a much higher height (around 7-9 feet) and if possible closer to a nearby house or other man-made building. The House Sparrow will often move to the new, higher house. This can facilitate inbox trapping."
However, this experiment showed a definite House Sparrow preference for post-mounted 1-holers over (higher) hanging 2-holed boxes. The reason for the preference is not known.
MAINTENANCE: Hanging boxes do not require the trouble and expense of post equipment. The only box maintenance necessary is to periodically check to make sure that the 1/4" hanger rod piercing the roof (secured with lock nuts) is nice and tight and to prune branches so there is a clear path to lift the box up and down through the tree.
TRAPPING: These boxes can be used in conjunction with trapping. At test sites, however, no trapping is permitted. If trapping and other gadgets or techniques (pairing) are implemented in conjunction with 2-holed box experiments, successes tend to be credited to monitor actions rather than Bluebird actions.
Trail Details:
Bet did a great job of documenting 2007 events with photos. Only three eggs were seen in the Eastern Bluebird nest and close (zoomed in) inspection of the egg photo shows what looks to be a tiny spot (hole) in the upper egg and small (non-pierced dent) in another. There were House Wren problems in a nearby Titmouse box and that could explain why only three eggs were in the nest and why only two eggs hatched.
Another interesting observation is that Bet's notes refer to the nest in this deep box as being "tall". Some monitors don't build deeper boxes because they think Bluebirds will simply fill the box with a high nest and, thus, negate any advantage of building deep boxes. Notice in the two photos (below) that only the side rim of the nest is tall. The second photo shows chicks snuggled deep within the nest center so that they are within a couple of inches of the floor. (The label at the back of the box in the first photo will give perspective to the relationship of the chicks to the floor in the second photo.)
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