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THE WILSON JOURNAL OF ORNITHOLOGY • Vol 124. No. 4. December 2012 
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The Wilson Journal of Ornithology 124(4):820-824, 2012 
Wint D M | crohabltat Foraging Preferences of Sympatric Boreal and 
Black-capped chickadees in Michigan’s Upper Peninsula 
Zach G. Gayk 1-2,3 and Alec R. Lindsay 1 2 
ABSTRACT.—We examined differences in microhab- 
itat use between Boreal (Poeeile hiuisonicus ) and Black- 
capped chickadees (P atricapillus) where they co-occur near 
Marquette. Michigan. USA. Twenty-four Boreal and 37 
Black-capped chickadees were followed during 60 hrs of 
field observation. Boreal Chickadees foraged only in three 
conifer species. 76% of which were black spntce (Picea 
mariana). while Black-capped Chickadees foraged widely 
across six coniferous and three deciduous tree species. 
Analysis of foraging data categorized by zones within 
conifer trees indicated high niche overlap (0.676) between 
Boreal and Black-capped chickadees across all foraging 
zones. Individual comparisons on a zone-by-zone basis 
revealed a significant difference in foraging occupancy in the 
medial portion ol the crowns of conifer trees IP = ().(XX)2) 
Our results indicate exclusive use by Boreal Chickadees of 
den.se medial foliage within the top 3 m of conifer crowns 
Received 22 March 2012. Accepted 3/ July 2012 
1 Department ol Biology, Northern Michigan University. 
University. 1401 Presque Isle Avenue. Marquette, Ml 49855 . 
2 Current address: Zoology and Physiology Department. 
WY V 8207 , i°USA° min ^ University Avenue, Laramie. 
Corresponding author; e-mail: zgayk@sbcglobaI.net 
Niche partitioning in birds has been widely 
reported between species with similar morpholog¬ 
ical lealures, body sizes, and diets (MacArthur 1958. 
Reynolds and Meslow 1984). or between males and 
females ol the same species that have divergent 
foraging strategies (Williams 1980. Radford and du 
Rlessis 2003). Two congeneric species. Black- 
capped and Boreal chickadees ( Poeeile spp.). often 
loiuge together in mixed-species flocks within 
boteal lorcsts ol Upper Michigan during winter. 
Black-capped Chickadees (P. atricapillus ) are 
abundant winter residents across a w ide spectrum 
of Forested and scrub habitats, but Boreal Chicka¬ 
dees ( P. hudsoniem) are rare residents within 
160 km ol their southern range boundary, they 
(Kvut in lowland black spruce ( Picea manana ) 
forests which are localized within the predominantly 
deciduous forest matrix of this region (Binford 
2006). All members of the genus Poeeile have 
similar food habits and body sizes, and forage for 
arboreal insect larvae and seeds. Dhondt (1989) 
concluded that non-overlapping distributions of 
North American chickadees indicated either range 
replacement (allopatry) or habitat partitioning, to 
