McElhone et al. • HABITAT CHANGE AND CERULEAN WARBLERS 
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TABLE 3. Land cover and fragmentation metrics based on aerial photographs for the middle (1982/1985) and late 
(2000/2003) time periods and Cerulean Warbler detections during 5 years surrounding each aerial photograph year for all 
240 stops (df = 234) and 76 (df = 70) presence-only stops on six BBS routes in West Virginia and Ohio. 
All slops Presence-only slops 
Middle 
X ± SE 
Late 
X ± SE 
F 
p 
Middle 
X ± SE 
Late 
X ± SE 
F 
p 
Landcover % 
Deciduous/mixed forest 
58.9 ± 1.7 
62.0 ± 1.6 
0.97 
0.32 
69.9 ± 2.5 
74.4 ± 2.1 
0.73 
0.39 
Coniferous forest 
1.0 ± 0.4 
0.8 ± 0.3 
0.16 
0.69 
1.1 ± 0.6 
0.7 ± 0.6 
0.92 
0.34 
Developed 
9.7 ± 1.0 
14.7 ± 1.4 
9.4 
0.002 
5.4 ± 1.2 
8.6 ± 1.4 
5.08 
0.03 
Agriculture 
30.5 ± 1.6 
22.5 ± 1.4 
9.88 
0.002 
23.7 ± 2.2 
16.3 ± 1.8 
4.28 
0.04 
Fragmentation metrics 
Max forest patch (ha) 
13.4 ± 0.3 
10.4 ± 0.3 
2.5 
0.12 
11.2 ± 0.1 
12.0 ± 0.5 
1.33 
0.25 
Core forest (%) 
14.8 ± 0.9 
16.6 ± 0.8 
2.96 
0.09 
18.9 ± 1.4 
20.9 ± 1.3 
0.92 
0.34 
Edge density (m/ha) 
142.1 ± 3.0 
144.8 ± 3.3 
0.08 
0.77 
139.9 ± 5.6 
139.3 ± 6.1 
0.04 
0.85 
Cerulean Warblers detections/stop 
Average 
0.09 ± 0.02 
0.06 ± 0.01 
4.6 
0.03 
0.28 ± 0.04 
0.19 ± 0.02 
7.77 
0.007 
Maximum 
0.23 ± 0.03 
0.21 ± 0.03 
1.07 
0.30 
0.71 ± 0.08 
0.67 ± 0.07 
2.70 
0.10 
probably was the result of agricultural field 
abandonment and forest succession as suggested 
by others (Keller and Scallan 1999, Betts et al. 
2007). Similarly, Ban et al. (1995) found an 
increase in forest cover from 1963 to 1988 within 
280 m of roads in western Ohio. Many agricultural 
fields may have been abandoned during the early 
time period, but the successional woody vegetation 
was not distinguishable from active agricultural 
fields on aerial photographs. Sufficient time had 
elapsed by the middle time period for abandoned 
agricultural fields to develop into early stage 
forests that could be differentiated on aerial 
photographs, but these young forests were likely 
less suitable Centlean Warbler habitat. Young 
forests consist mainly of shrubs and pole-sized 
trees, lacking the large mature trees (Hamel 2000b) 
and horizontal and vertical structural diversity that 
Cerulean Warblers prefer (Weakland and Wood 
2005, Perkins 2006), although young forests are not 
TABLE 4. Land cover and fragmentation metrics based on 1992 and 2001 NLCD and Cerulean Warbler detections for 
1990-1994 and 1999-2003 for 1,375 stops (df = 1,346), and for 344 presence-only stops (df =319) along 28 BBS routes in 
West Virginia, Ohio, and Kentucky (FF edge density = Forest-forest edge density, FNF edge density = Forest-nonforest 
edge density). 
All slops Presence-only slops 
1992 
X ± SE 
2001 
X * SE 
F 
p 
1992 
X ± SE 
2001 
X i SE 
F 
p 
Landcover (%) 
Deciduous/Mixed forest 
64.3 ± 0.8 
59.4 ± 0.7 
38.94 
<0.001 
81.6 ± 1.0 
74.4 ± 0.8 
45.88 
<0.001 
Coniferous forest 
3.3 ± 0.2 
1.5 ± 0.1 
161.09 
<0.001 
3.8 ± 0.3 
0.9 ± 0.2 
125,09 
<0.001 
Non-forest 
32.4 ± 0.8 
39.1 ± 0.7 
79.08 
<0.001 
14.6 ± 1.0 
24.8 ± 0.8 
110.07 
<0.001 
Fragmentation metrics 
Max forest patch (ha) 
7.6 ± 0.1 
8.0 ± 0.1 
7.2 
0.007 
9.0 ± 0.2 
9.7 ± 0.2 
3.49 
0.063 
Core forest (%) 
9.7 ± 0.3 
9.1 ± 0.3 
10.99 
0.001 
13.4 ± 0.5 
13.5 ± 0.6 
0.15 
0.698 
FF edge density (m/ha) 
20.5 ± 0.4 
7.5 ± 0.2 
423.04 
<0.001 
25.8 ± 0.7 
9.2 ± 0.4 
255.08 
<0001 
FNF edge density (m/ha) 187.8 ± 2.8 
Cerulean Warbler detections/stop 
172.9 ± 1.8 
11.34 
0.001 
159.9 ± 5.7 
179.1 ± 3.2 
54.24 
<0.001 
Average 
0.08 ± 0.01 
0.10 ± 0.01 
2.54 
0.11 
0.31 ± 0.03 
0.41 + 0.03 
5 45 
0.03 
0.0’ 
Maximum 
0.19 ± 0.01 
0.30 ± 0.02 
1.81 
0.18 
0.76 ± 0.05 
0.99 ± 0.05 
5.60 
