Wood and Perkins • CERULEAN WARBLER ACTIVITIES 
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Black 
Black 
Black Red Oak 
Sugar 
Tulip White Ash 
Chestnut Hickory 
Red Oal 
Cherry 
Locust 
Walnut group 
Maple 
Poplar 
Oak spp. 
group 
Hart Ridge 
Snake Ridge 
FIG. 1. Percent occurrence of male Cerulean Warbler observations among tree species most often used for singing in 
core compared to non-core areas of territories on two sites in Wetzel County. West Virginia. May-June 2005. 
areas may enhance song broadcast to neighbors. 
Barg (2002) hypothesized that song-posts would 
be near canopy gaps or in trees with less dense 
foliage where song attenuation and reverberations 
olf foliage were reduced. We found that singing 
behavior near canopy gaps occurred more than 
expected in the upper-canopy. We also detected 
no effect of the proximity to canopy gaps on 
singing, foraging, and perching activities, even 
though canopy gap densities were highest within 
core areas (Perkins 2006). Core areas are likely 
selected for a combination of complex reasons. 
Male Cerulean Warblers foraged more than 
expected outside of core areas. Similarly, core 
areas did not serve as foraging centers for 
Cerulean Warblers in Ontario (Barg et al. 2006). 
h appears that males use core areas primarily as 
singing locations and may forage within them 
only opportunistically. However, males foraging 
within core areas used the mid-canopy strata 
more than expected. They may forage higher 
within than outside of core areas simply because 
singing occurred at higher canopy levels and the 
primary purpose of core areas appeared to be lor 
singing. 
Use of different tree species is quite variable 
across the range of the Cerulean Warbler, 
although the importance of oaks, hickories, and 
maples is often noted in the Appalachian region 
for singing and foraging (Rosenberg et al. 2002). 
Barg et al. (2006) found that, for IS males in 
Ontario, the five most commonly used tree species 
for singing, foraging, and perching were sugar 
maple (36.5%), bilternut hickory (C. cordiformis ; 
30.0%), white ash (12.1%), oaks (8.1%), and 
American elm (Uhnus americana ; 5.7%); males 
preferred sugar maple and bittemut hickory as 
song-posts. Foraging males preferred hickories in 
Illinois (Gabbe et al. 2002) and sugar maple, 
chestnut oak. and species of hickory in the central 
Appalachians while avoiding the red oak group 
(George 2009). Use of tree species varied between 
our two study sites, primarily as a result of 
differences in tree species composition. Oaks and 
hickories occurred less often on our mesic site and 
male Cerulean Warblers instead used cherries, 
locusts, and walnuts. Barg ct al. (2006) found the 
distribution of tree species used lor song-posts 
differed between core and noncore areas; males in 
noncore areas predominantly used sugar maples 
(34.4% of observations) whereas in core areas 
they predominantly used bitternut hickories 
(36.8% of observations). They suggested that 
male Cerulean Warblers appeared to be selecting 
trees for song-posts that had delayed development 
of leaves. We similarly found hickories used as 
singing locations within core areas at our xeric 
site, while males at our mesic site used black 
cherry within core areas. Cerulean Warblers 
appear to be flexible in use of tree species for 
