SHORT COMMUNICATIONS 
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TABLE 1. Species use of 100 27.5-cm length x 9.5-cm inside diameter, polyvinyl chloride (PVC) nest tubes attached 
horizontally to utility poles at 3 m in height, on the National Aeronautics and Space Administration’s Plum Brook facility in 
Erie County. Ohio. USA. Each tube had a 5.1-cm diameter entrance. Nesting data were collected from 4 May through 12 
August, 2009 and from 21 April through 8 September 2010. 
Species 
Year 
No. nests 
No. dutches depredated 
No. nests failing* 
% Nests fledging yi 
Easiem Bluebird 
2009 
15 
0 
0 
Unknown 
2010 
24 
1 
0 
96 
European Starling 
2009 
0 
2010 
0 
House Sparrow 
2009 
0 
2010 
2 
0 
0 
100 
House Wren 
2009 
21 
0 
0 
Unknown 
2010 
18 
2 
1 
83 
Tree Swallow 
2009 
12 
0 
0 
Unknown 
2010 
43 
1 
0 
98 
Nestlings discovered dead in nest, but no evidence of predation. 
Ness were not monitored through fledging in 2009. 
longer a factor, Wc removed nest material from 
the previous year and closed the tubes until 14 
April. We added 10 PVC tubes (27.5-cm long X 
17 cm) with a 5.1-cm diameter entrance to 
investigate the effect of nest tube inside diameter 
on use by starlings and native species. These 
larger tubes were attached to utility poles in the 
same manner as the smaller tubes, and were 
positioned at 240-m intervals. We opened these 
larger tubes on 15 June. Our nest-check protocol 
followed that described for the 2009 breeding 
season for all sites with the addition of following 
each nesl through fledging. We ended our 2010 
daia collection on 8 September. 
RESULTS 
Fifty of the smaller tubes were used for nesting 
in 2009. 49 by Eastern Bluebirds (Sicilia sialis). 
Free Swallows ( Tachycineta hi color), or House 
Wrens (Troglodytes aedott) w ith one nest uniden¬ 
tified to species (Table 1). Eighty-seven of the 
smaller tubes were used in 2010 with only two 
being occupied by a non-native cavity-nesting 
species. These tubes were occupied by House 
Sparrows (Passer domesticus) in close proximity 
10 sites where bird seed was provided by an 
adjacent land owner. Ninety-four percent of the 
smaller tubes with native species fledged young 
'Fable 1). Starlings were observed sitting on and 
entering the small tubes in 2009 and 2010. but no 
evidence of starling nesting was found in either 
year. 
Starlings nested in two of our larger tubes (25% 
°f occupied tubes) while six of the remaining 
eight tubes contained nests of Eastern Bluebirds 
(n = 1 positive identification by egg; 3 possible) 
and Tree Swallows (n = 2 nests). 
DISCUSSION 
Our nesting data over two breeding seasons 
demonstrate successful use of a PVC tube cavity 
by three native passerine species and avoidance 
by European Starlings, likely due to a reduced 
vertical depth. Starlings are recognized as adapt¬ 
able to a range of cavity dimensions in human 
structures (Savard and Falls 1981. Feare 1984). 
but cavity vertical depth may serve as a selective 
factor in accessible cavities when a variety of 
cavity dimensions arc available. For example, 
Mazgajski (2003) found that starlings selected 
nest boxes with a 22-cm vertical depth over 
similar boxes adjusted to achieve shallower 
vertical depths, possibly because of benefits in 
limiting predation. The smaller PVC tubes used in 
2009 and 2010 replaced wood nest boxes (28-cm 
inside length X 12-cm width X 13- to 16-cm 
vertical distance from floor to sloped ceiling with 
5.1-cm entrance) previously used in successive 
experiments with nesting starlings (Dolbeer el al. 
1988. Belant et al. 1998. Seamans et al. 2001, 
White and Blackwell 2003). Starling use of the 
wood nest boxes in these studies ranged trom 58 
to 97% occupancy. McGilvrey and Uhler (1971) 
reported reduced starling use of 61-cm long X 
30.5-cm diameter cylinder Wood Duck (Aix 
sponsa) tubes mounted horizontally, particularly 
when the openings exceeded 7.6 cm X 10.2 cm. 
We speculate that light penetration, lack of clear 
head space after nest construction or perceived or 
realized predation risk contributed to the reduced 
