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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123. No. 3. September 2011 
TABLE 1. Nest-location and nest-patch variables included in the analyses of Grey-backed Thrushes in Dagang Forestry 
rami, China, in 2008. ; 
Variable 
Nest-location 
Nest-tree DBH 
Nest height 
Distance from nest to 
main stem 
Horizontal exposure 
Vertical exposure 
Total exposure 
Nest-patch 
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 
Description 
Reference 
Diameter at breast height of the vegetation 
supporting the nest, averaged for vegetation 
with multiple stems 
Distance between the ground and the upper 
margin of nest 
Distance between the center of nest and the 
main stem of nest tree 
Visibility of the nest in a horizontal plane at nest 
height 
Visibility of the nest in a vertical plane 
Combination ot vertical and horizontal exposure 
Benin 1977 
Forschler and Kalko 2006 
Hoover and Brittingham 1998 
Martin and Roper 1988 
Gotmark et al. 1995 
Hatchwell et al. 1996 
Johnson 1997 
Distance of the nest to the nearest external edge 
Distance of the nest to the closest path 
(-2 m wide) 
Percentage of the forest floor covered by 
vertical projection of tree (> 5 m) crowns 
f roportum of the forest floor covered by herbs 
between 0 and 0.5 m 
Average of | () random measurements of 
height of grasses in the 0.04-ha circle 
Density of main stents of shrubs below breast 
height along two arm-length perpendicular 
transects (- 2 m wide) that bisected the 
0.04-ha circle 
Total area calculated from DBH of all the 
standing trees (3 cm < DBH < 8 cm) 
Total area calculated from DBH of all the 
standing trees (DBH 2 8 cm) 
Driscoll et al. 2005 
Newell and Kostalos 2007 
Miller et al. 1998 
Sargent et al. 2003 
Berlin 1977 
Eiserer 1980 
Yang and Tian 1987 
Driscoll et al. 2005 
Driscoll et al. 2005 
Kelleher and O’Halloran 2007 
the horizontal exposure. The number of circle 
more than half-visible from each dtrection at 
ecold Th nCC ° f 3 m <at neS ‘ he '£ht) wa 
recorded The exposure value of each nest wa 
computed by summing the number of circles fron 
the four lateral directions and dividing hy 40 Tht 
honzontal exposure was ranked as one if the value 
was between 0 and 20% (including 20%) ,h er 
•wo, three four, and five by 20% itferemems 
Vertical exposure was divided into upper and 
ground-level exposure. The W area over "he 
"mallT a"” area f ° r shadin S relative to the 
unn aged are “ eaeh nest (0.0117 m ; ) The 
upper exposure was estimated as ,h. 
exposure between 0 and „ , * percent 
•he nest ,o asses^ a i ' m area "ver 
predators. Ground-lever"™* 01 ^ " eSl “ erial 
Predators on the smiun 1 P ° SUre of ,he nest to 
ground was estimated from the 
peicent exposure between 0 and 0.5 m above the 
ground within a radius of 3 m centered on each 
nest. The upper and ground-level exposure was 
ranked as one if the peicent exposure was between 
0 and 20% (including 20%). then two. three, four, 
or five, for percent exposure increasing by 20 % 
increments. Total exposure equaled the sum of 
horizontal and vertical exposure. For example, 
total exposure of a nest would be 11 when its 
horizontal, upper and ground-level exposure was 
two. five, and four, respectively. Nests with values 
closer to 15 had greater exposure to predators. 
Distance to the closest path and forest edge 
(most have forest-tannland edge with few forest¬ 
ore st opening edge) was measured by pacing, and 
recorded as 150 m if > J 5 0 m We measured the 
following nest-patch variables within a 0.04-lu 
circular plot centered on the nest directly: canop) 
