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1 September 2018 Potential winter niche partitioning between Tufted Titmice (Baeolophus bicolor) and Black-capped Chickadees (Poecile atricapillus)
John Correia, Sylvia L. Halkin
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Abstract

The northward range expansion of Tufted Titmice (Baeolophus bicolor) has increased their contact with Black-capped Chickadees (Poecile atricapillus). Tufted Titmice and Black-capped Chickadees were observed foraging naturally in 3 Connecticut forests and at a residential bird feeder to assess the degree of foraging niche overlap and competition between the 2 species during winter 2015–2016. Chickadees spent significantly more time in the outer portion of the upper canopy than did titmice, which used different subsections of the canopy fairly evenly. Chickadees also foraged in shrubs significantly more than did titmice. Titmice spent much of their time foraging on the ground, which chickadees largely avoided. These differences may be explained by the ability of larger titmice to better forage on larger branches and to flip leaves to forage on the ground. The larger size of titmice may also explain their dominance to chickadees at the bird feeder. Given a choice between safflower seeds, black oil sunflower seeds with shells, and black oil sunflower seeds without shells, both species took some of each, but titmice most often chose safflower seeds while chickadees most often chose black oil sunflower seeds without shells. Although chickadees and titmice showed some overlap in their food choices and foraging locations, the significant differences we found may mitigate competition between these species, at least under the environmental conditions of this study. As titmice continue to expand their range northward, competition may be greater in areas with harsher winter conditions and less human-supplied bird seed.

John Correia and Sylvia L. Halkin "Potential winter niche partitioning between Tufted Titmice (Baeolophus bicolor) and Black-capped Chickadees (Poecile atricapillus)," The Wilson Journal of Ornithology 130(3), 684-695, (1 September 2018). https://doi.org/10.1676/17-072.1
Received: 13 May 2017; Accepted: 28 February 2018; Published: 1 September 2018
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