498 
THE WILSON JOURNAL OF ORNITHOLOGY • Vol 123. No. 3. September 2011 
TABLE 3. Habitat measurements (mean ± SE) at nest sites and random plots, and successful and depredated nest sites 
for Grey-backed Thrushes in Dagang Forestry Farm, China, in 2008. Significance tests were conducted between nest sites 
and random plots, and successful and depredated nest sites. 
_ Vanables _Nesniites (n - 79) Random plots <n = 79) Successful (n = 29) Depredated (n = 35 ) 
Nest-location 
Nest-tree DBH (cm) 
Nest height (m) 
Distance from nest to main 
stem (cm) 
Horizontal exposure 
Vertical exposure 
Total exposure 
Nest-patch 
Distance to edge (m) 
66.73 ± 54.23 
Distance to path (m) 
18.33 ± 23.31* 
Canopy cover (%) 
83.76 ± 12.42 
Ground cover (%) 
65.95 ± 13.50* 
Height of ground cover (m) 
0.30 ± 0.09** 
Density of shrubs (inds./m 2 ) 
1.21 + 0.46** 
Basal area of small 
2.24 ± 0.78** 
trees (m 2 /ha) 
Basal area of large trees (nf/ha) 
16.87 ± 7.25 
* P < 0 05 (t0mparis0n5 be,wcen successful and depredated nests). 
** P <0.01, 
8.70 ± 5.47 
8.44 ± 4.73 
1.93 ± 1.05 
1.89 ±0.55 
8.31 ± 17.65* 
25.54 ± 30.66* 
3.21 ± 0.89“ 
3.46 ± 0.76' 
4.03 ± 1.85 
3.89 ± 1.52 
7.24 ± 2.37 
7.34 ± 1.88 
74.03 ± 
56.18 
70.83 ± 55.36 
56.60 ± 39.33 
24.00 ± 
21.42* 
20.76 ± 27.59 
16.23 ± 14.00 
80.63 ± 
16.92 
85.17 ± 11.48 
82.49 ± 10.27 
71.84 ± 
16.35* 
64.31 ± 13.31 
68.14 ± 10.66 
0.36 ± 
0.14** 
0.29 ± 0.07 
0.32 ± 0.08 
0.95 ± 
0.42** 
1.32 ± 0.42“ 
1.13 ± 0.38' 
1.64 ± 
0.88** 
2.15 ± 0.75 
2.30 ± 0.51 
17.95 ± 
8.53 
16.76 ± 6.93 
16.58 ± 5.82 
zontal exposure); of these, 33% (n = 14) were 
successful. However, among the 34 residual nests 
whose three exposure indexes were low (< 3). 
44% (n = 15) succeeded. 
DISCUSSION 
Nest-site Characteristics.— Grey-backed Thrush¬ 
es nested in areas with lower ground cover and a 
higher density of small trees and shrubs. Other 
researchers have found that shrub-nesting birds, 
such as Wood Thrush and Song Thrush (Hoover 
and Brittingham 1998, Kelleher and O'Halloran 
2007), build nests in areas with higher shrub 
densities. Our results were consistent with their 
findings (Table 2). Dense shrubs may reduce the 
risk of predation (Joem and Jackson 1983, Martin 
1993). and provide shade to protect nestlings from 
inclement weather (Weidinger 2009). 
China, in 2008. Models wereranked according toAIc' 6 -12 G ^ ey ' b “ ckcd Thrushes in Dagang Forestry Farm, 
sampling plots. ® referred to 21og-likeIihood. All models used n = 158 
ID 
1 
2 
3 
4 
5 
6 
* The lov 
Predictors 
Distance to edge + distance to path + canopy 
cover + ground cover + height of ground 
cover + density of shrubs + basal area of 
small trees + basal area of large trees 
Null model (only y intercept) 
Height of ground cover + density of shrubs 
+ basal area of small trees 
Distance to path + height of ground cover 
+ density of shrubs + basal area of small tre 
Dcnsuy ol shrubs + basal area of small trees 
Distance to path + density of shrubs + basal 
area of small trees 
“ AJC ‘ VB " , P tor lhi» analysis was 197.25. 
-2log(/) k 
206.17 9 
221.06 1 
197.25 4 
197.61 5 
197.92 3 
198.54 4 
AAIC/ 
W, 
8.92 
0.004 
23.82 
0.000 
0.00 
0.325 
0.37 
0.270 
0.68 
0.231 
1.30 
0.170 
