Large 1-Holed vs. Large 2-Holed Box Test

Dick Purvis (Bluebird Coordinator of Orange County, Calif.), thought it might be the large box size (rather than the 2 holes) which tipped the advantage to western bluebirds (WEBL) over house sparrows (HOSP) on my trail of 2-holed mansions.   By contrast, I believe the second hole plays a role in the success of nesting bluebirds over house sparrows.  To do a comparison, Dick agreed to place three of my large 1-holed boxes and three 2-holed boxes at house sparrow problem sites during 2000 and 2001.  

In order to cull the 2-holed mansion results,  boxes specified as 2-holed mansions in Dick's report (see end of page) are listed in the table below.  Dick's full report is given below the table. The large 2-holers were very successful.  

Loc. / Problem Site  Results WEBL?

HOSP?

 Linda's Comments  
SCHWEITZER;  1 Box

2001 =  HOSP & WEBL fighting over standard box.  Dick switched the standard box with 2-Holer

 WEBL fledged from  2-holer.  Then HOSP moved in & laid eggs. (Emptied).

Then 1/2 WEBL nest

 WEBL Fledged HOSP tried after WEBL fledged Dick says " this was the first time I have ever seen bluebirds win the battle over sparrows."   

Log dates were not provided so we do not know if HOSP took the box immediately after WEBL fledged.. After HOSP were evicted, bluebirds reclaimed the box.  The unfinished bluebird nest was most likely too late in the season to complete.

  
           
HART PARK;  3 Boxes

2001 = 2-holer and  large 1-holed box hung at HOSP problem site

 5 successful WEBL nests WEBL Fledged   Both experimental large boxes were successful  
           
AMERIGE PARK;  1 Box

2000 = 2-holer hung at HOSP problem site

 2 Successful WEBL nests WEBL Fledged   2-holed box successful  
           
FORD PARK;  1 Box

2000 = 2-holer hung at HOSP problem site

 2 Successful WEBL nests WEBL Fledged   2-holed box successful  
FORD PARK;  1 Box

2001 = 2-holer (see prev. yr.)

 

 Dick removed 2-holer when he saw a HOSP nest    HOSP nest. It was not noted whether there was bluebird competition.  HOSP nest should have been removed and box left in place.  
           
BOYSEN;  1 Box

2001 = 2-holer hung at HOSP problem site

 Dick removed 2-holer when he saw a HOSP nest   HOSP nest. It was not noted whether there was bluebird competition.  HOSP nest should have been removed and box left in place.  

 

Dick's complete report of 11/1/01 (including 1-holed box results) is copied below.  Note that Dick tends to remove successful test boxes and put back standard boxes the following year.  Why he removed successful test boxes is unknown.

Here are the final results of my testing large boxes versus standard ones: 

Koch Park, 3 boxes with previous history of HOSP problems 
2000 3 large boxes replaced standard boxes. 5 nests. No HOSP problems 
2001 3 standard boxes replaced large ones. 6 nests. Probably no HOSP 
problems. 2 nests - all young dead. 1 nest bad eggs. 

Oak Knoll, 1 box 
2000 standard box, HOSP problems. Paired box. WEBL OK in one HOSP in 
other. 
2001 replaced with large 1-holer. HOSP and WEBL fighting. HOSP won. 
paired with standard box. HOSP took both. Took all down. 

Boysen Park, 1 box 
2000 standard box. HOSP nest over WEBL nest. Moved box. HOSP nest. 
took down. 
2001 put up large 2-holer. HOSP nest. Took down. 

Juarez Park, 1 box 
2000 standard box. HOSP problems. Took down. 
2001 large i-holer put up. HOSP nest over WEBL nest. Cleaned. Box stolen 

Schweitzer Park, 1 box 
2001 standard box. HOSP nest with egg. HOSP WEBL fighting. Replaced 
with 2-holer. WEBL nest - fledged OK. HOSP nest with eggs. Emptied. 
1/2 WEBL nest. No further activity. 

Hart Park, 3 boxes 
2000 HOSP problems at 2 boxes. 
2001 replaced 2 boxes with 1-holer and 2-holer. 5 successful WEBL nests. 

Amerige Park, 1 box 
1999 severe HOSP problems 
2000 replaced with 2-holer. 2 successful WEBL nests. 
2001 replaced with standard box. 2 WEBL nests. No problems 

Ford Park, 1 box 
1999 severe HOSP problems. 
2000 replaced with 2-holer. 2 successful WEBL nests 
2001 HOSP nest. Took down 2-holer. Put up standard box 1 block away. 
one WEBL nest fledged. Then HOSP nest. Took down box. 

These results seem to be somewhat mixed although there may be an advantage for the large boxes. The Schwietzer
Park event was the first time I have ever seen bluebirds win the battle over sparrows.  

[End of Dick Purvis 11/1/01 report]

 

You can reach me at: lviolett@earthlink.net

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