Individuals that settle in poor habitats may reduce resource investments in various life history traits; for example, resources may be withheld from costly advertisement signals. There may be geographic variation in advertisement levels that correspond with habitat quality; however, this is poorly documented and it is unclear whether such habitat effects have consequences for the function of mate‐choice signals within habitats. We examined song output of male black‐capped chickadees (Poecile atricapillus) during the dawn chorus in two contrasting habitats (mature forest vs. young forest) known to differ in quality. Dominance rank is indicative of phenotypic quality in this species and was assessed during the preceding winter. We measured the song output of males participating in the dawn chorus during the nesting/egg laying period. Males living in young forest had reduced song output; however, a habitat–rank interaction term showed that dominant birds accounted for most of this difference. This suggests that signal reliability might be lost in poor habitats. We generate several hypotheses to explain these findings.

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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Genetic analysis of passerine birds often finds evidence of extra–pair copulations within species, but genetic evidence of intraspecific brood parasitism (IBP) and quasi–parasitism (Q–P) are relatively rare. Further, it is even rarer for genetic patterns that might indicate quasi–parasitism (resident male sires offspring through extra–pair copulations, and allows the female to lay these within the male’s nest) to be coupled with observational evidence of this behavior. In this paper, we report behavioral observations surrounding the nest of black–capped chickadee, one of the few species in which both IBP and Q–P have been detected through a genetic analysis. These were later confirmed to have young genetically mismatched with both attending parents, as well as mismatched with the attending female but sired by the attending male. The behavioral patterns associated with this nest are contrasted with the two previously reported cases of IPB/Q–P in this species, and suggest that rare ‘detection’ of quasi–parasitism may be explained by converging patterns of extra–pair behavior and the rarer strategy of intraspecific brood parasitism.