Communication breakdown? Habitat influences on black-capped chickadee dawn choruses |
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Authors: | Ingebjørg Jean K Hansen Ken A Otter Harry van Oort Carmen I Holschuh |
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Institution: | (1) Ecosystem Science and Management Program, University of Northern British Columbia, 3333 University Way, Prince George, V2N 4Z9, BC, Canada |
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Abstract: | The dawn chorus of the black-capped chickadee (Poecile atricapillus) is a communication network that functions in the dissemination of essential information for both males and females. Habitat
type may influence the performance of this network, and if recognized, chickadees may attempt to behaviorally compensate for
detrimental changes in the form of increased movement. We studied the dawn chorus of 66 black-capped chickadees in two adjacent,
yet structurally different, habitats (disturbed and undisturbed) during the summers of 2000–2003 and recorded via point counts
the number of neighboring males heard singing simultaneously while following a focal chorusing male and observing his movement.
A transmission study to detect differential degradation due to habitat type was also conducted within the same research site.
Observers in the disturbed sites heard significantly fewer neighboring males in the focal male's territory than in the undisturbed
site, yet individual movement did not differ between habitat types. Propagation of song of varying frequencies, as measured
by entropy, suffered less degradation in the disturbed site for high-frequency songs, but there was no effect of habitat on
low- or mid-frequency songs. Greater interneighbor distance in the disturbed site likely explains some of the reduction in
audibility of neighboring males during the dawn chorus, but the reduced condition of birds in the disturbed site (implicated
from other studies) may also be a factor in explaining the difference in networks. The findings of this study suggest that
chickadees in the disturbed habitat are experiencing a compromised communication network, which could impact breeding and
other social behaviors. |
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Keywords: | Communication networks Song transmission Habitat effects Black-capped chickadee Peocile atricapillus |
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