The Wilson Journal of Ornithology 124(3):497-505, 2012 
BEHAVIORAL ACTIVITIES OF MALE CERULEAN WARBLERS IN 
RELATION TO HABITAT CHARACTERISTICS 
PETRA BOHALL WOOD 14 AND KELLY A. PERKINS’' 
ABSTRACT.—Activities of 29 male Cerulean Warblers (Setophaga cerulea) were quantified on two sites in West 
Virginia during May-June 2005. Singing and foraging were the most common of 11 observed behavioral activities (81.6%), 
while maintenance and mating behaviors were uncommonly observed. Male activity differed among vegetative strata (P = 
0.02) with lower- and mid-canopy strata used most often {10% of observations), especially for foraging, perching, and 
preening. The upper-canopy was used primarily for singing, particularly within core areas of territories and in association 
with canopy gaps. Foraging occurred more than expected outside of core areas. Males were associated with canopy gaps 
during 30ft of observations, but the distribution of behavioral activities was not significantly related (P = 0.06) to gap 
presence. Males used 23 different tree species for a variety of activities with oaks t Quercus spp.) used most often on the 
xeric site and biack cherry (Prumis serntina ) and black locust (Rohinia pseudoacacia) on the mesic site. Tree species used 
for singing differed between core and non-core areas f P - 0.0(H)!) but distribution of singing and foraging activity did not 
differ among tree species (P = 0.13). Cerulean Warblers appear to be flexible in use of tree species. Their use of different 
canopy strata for different behavioral activities provides an explanation for the affinity this species exhibits for a vertically 
stratified forest canopy. Received 31 August 2011. Accepted If) January 2012. 
Quantifying behavioral activities (Altmann 
1974) can provide useful insights into a species' 
habitat needs (Graham 2001, Fleischer et al. 2003, 
Aborn and Moore 2004). Habitat characteristics of 
Cerulean Warblers (Setophaga cerulea) have been 
examined extensively (e.g., Weakland and Wood 
2005. Barg el al. 2006, Roth and Islam 2008, 
Bakermans and Rodewald 2000. Hartman el al. 
2009) bui few studies have quantified behavioral 
activities relative to habitat. Barg et al. (2006) 
studied allocation of singing, foraging, and 
perching behaviors by male Cerulean Warblers 
among tree species and canopy height while 
Gabbe el al. (2002) anil George (2000) examined 
foraging preferences among tree species. 
Canopy gaps and a heterogeneous canopy 
structure are thought to be important resources 
tor Cerulean Warblers (Oliarnyk and Robertson 
1996, Jones and Robertson 2001. Weakland and 
Wood 2005. Wood et al. 2006. Roth and Islam 
2008). Cerulean Warblers often placed nest sites 
within 30 m of a canopy gap in Ontario (Olinaryk 
and Robertson 1996) and gap densities were three 
U.S. Geological Survey. West Virginia Cooperative 
Fish and Wildlife Research Unit. West Virginia University, 
03 Percival Hall. P. O. Box 6125. Morgantown. WV 
26506, USA. 
West Virginia Cooperative Fish and Wildlife Research 
knit. Division of Forestry and Natural Resources. Wcsi 
Virginia University, 313 Percival Hall, P. O. Box 6125. 
Morgantown, WV 26506. USA. 
Current address New York Natural Heritage Program. 
625 Broadway. 5th Floor. Albany. NY 12233. USA. 
4 Corresponding author; e-mail; pbwood@wvu.edu 
times greater within core areas of territories than 
at random locations (Perkins 2006). Singing and 
foraging are two activities that may relate to gap 
presence. Gaps provide rich foraging opportuni¬ 
ties for passerines (Noss 1991. Rotenberry et al. 
1995, Smith and Dallman 1996). Higher insect 
abundance in gaps resulted from increased 
amounts of foliage in response to more light 
available to tree crowns surrounding canopy gaps 
(Blake and Hoppes 1986). Thus, Cerulean War¬ 
blers may spend more time near gaps to exploit 
prey resources. They also may use song posts near 
gaps for greater song projection due to reduced 
attenuation and reverberations off foliage (Barg 
2002 ). 
Mixed mesophytic (Hinkle et al. 1993) and 
Appalachian oak {Quercus spp.) (Stephenson et 
al. 1993) forests have high tree species diversity, 
and Cerulean Warbler use of specific tree species 
for singing and foraging has been documented 
throughout their range (Gabbe et al. 2002, 
Rosenberg et al. 2002. Barg et al. 2006, George 
2009). Timber harvesting as a habitat manage¬ 
ment tool for this species is being considered 
(e.g., Hamel et al. 2004, Wood et al. 2005, 
Bakermans and Rodewald 2009), but a better 
understanding of tree species used by Cerulean 
Warblers for all behavioral activities is needed 
before timber harvesting is applied extensively. 
We quantified behavioral activities of male 
Cerulean Warblers during the breeding season in 
north-centra] West Virginia. Specific objectives 
were to; (1) identify Cerulean Warbler behaviors 
and time allocated to each, and (2) examine if 
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