Carpenter et al • CERULEAN WARBLER MICROHABITAT ASSOCIATIONS 
211 
<N 
YTWA* 
Interior, 
deciduous forest 
•YTVI 
Mesic, 
bottomland 
NOP A# 
BLKJ* ACFL* • 
KEWA* LOWA 
CERW* 
• BGGN 
•WEWA 
•WBNUvi *SCTA 
.ETTI . .. 
•HOWA 
• BTNW 
•OVEN 
Xeric, 
upland 
Axis 1 
HAWO* CACH* 
COYE* RBWO* 
CARW* 
BHCO* 
YBCH* EAWP 
• YBCU 
• *WOTH 
N0CA EATO 
•*PIWO 
GCFL 
•BLJA 
• PRWA 
PIWA* 
AMCR DOWfO 
MODO* 
•WEVI 
suta*nobo 
Edge, 
mixed forest 
-2.0 
3.0 
FIG. 3. Plot based on detrended correspondence analysis of bird abundance from locations used and unused by 
Cerulean Warblers in northern Alabama during the 2005 and 2006 breeding seasons. Axis gradients represent general 
habitat preferences (Poole 2005). ACPI. (Acadian Flycatcher). AMCR tAmerican C row), AMRE i American Redstart), 
BEKJ (Belted Kingfisher). BGGN (Blue-gray Gnuleateher, Polioplila cueruleu i, BHCO (Brown-headed Cowhird), BLJA 
iBlue Jay). BTNW (Black-throated Green Warbler. Dendroica Virens). BWWA (Blue-Winged Warbler). CAC'H (Carolina 
Chickadee, Poccilc carolincnm), CARW (Carolina Wren, Thrynthonis ludoviciutm), CERW (Cerulean Warbler), COYE 
(Common Yellowthroat, Geotblypis rriclm), DOWO (Downy Woodpecker. Pit aides pubescent), EAPH (Eastern Phoebe. 
Stiyomis phoebe), EATO (Eastern Towhee. Pipiln erythrophthaluuis), EAWP (Eastern Wood-Pcwee, Contopps virens), 
ETT1 (Tufted Titmouse. Haealophus bicolor). GCFI. (Great C’rcsted Flycatcher. Myumbus crinftu .¥), HAWO (Hairy 
Woodpecker, Picoidfs viltosus). HOW A (Hooded Warbler, Wilmniu ciirina). INBU (Indigo Bunting), KEWA (Kentucky 
Warbleri. LOW A (Louisiana Watefthrusb), NOBO (Northern Bobwhiie, Colinus virgiitiiVIUS). NOCA (Northern Cardinal, 
Cardinalis cardinal is), NOPA (Northern Panda), OVEN (Ovenbivd, Seiunis aurocapilta), PIWA (Pine Warbler, Dendroica 
pinus). P1WO (Pileated Woodpecker. Dryocopus pileatus). PRAW (Prairie Warbler. Dendroica discolor), RBWO (Red- 
bellied Woodpecker), REV! (Red-eyed Vireo, Vireo olivaceus). SCTA (Scarlet Tanager, Piranga olivacea), SUTA 
(Summer Tanager, P. rubra). WBNU (White-breasted Nuthatch, Sirta carolinetisis), WEVI (White-eyed Vireo, Vireo 
griseus ). WEWA (Worm-eating Warbler. Helmitheros vermivurus). WOTH (Wood Thrush. Hyiocichla musletina), YBCH 
(Yellow-breasted Chat, Icteria virens), YBCU (Yellow-billed Cuckoo. Coccvzus americanus), YTVI (Yellow-throated 
Vireo. Vireoflavifrons). YTWA (Yellow-throated Warbler. Dendroica dominica). 
middle, and upper canopy heights (t = 1.69, df = 
97. P < 0.10: t = 2.58. df = 97. P < 0.01: 2 = 
- 1.68. df = 97. P < 0.09). greater canopy cover 
(Z = -3.48, df = 97. P < 0.01). larger diameter 
trees near plot center (/ = 5.49, df = 97, P < 
0.01 ), and larger canopy gaps (Z = -1.69, df = 
97, P < 0.09). They also occurred in areas with 
less complex canopy structure (/ = -1.64. df = 
97. P < 0.10) and fewer seedlings/shrubs (7 = 
-3.23, df = 97, P < 0.01). 
We extracted six components from the PCA, 
which accounted for 67.4% of the cumulative 
variance (Table 2). Canonical correspondence 
analysis produced four significant axes (F = 
1.46, P < 0.01 > that explained 83.8% of the total 
variance with the first two axes accounting for 
greater than half of the variability (53.9%). 
Cerulean Warblers displayed the strongest rela¬ 
tionships with the principal component represent¬ 
ing high percent deciduous basal area, fewer trees 
