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Dominance relationships structure many animal societies, yet the process of rank attainment is poorly understood. We investigated acquisition of social dominance in winter flocks and its fitness consequences in male black-capped chickadees (Poecile atricapillus) over a 10-year period. Age was the best predictor of rank, and paired comparisons showed high-ranked males to be older than their low-ranked flock-mates. When controlling for age, morphological variables did not predict male social rank, but high-ranked males were heavier, had lower fat scores and were in leaner condition than low-ranked males. Males that survived between years tended to increase in rank over time; however, the rate of rank advancement varied individually. Rank reversals between familiar contestants were rare, and changes in male social rank were associated with changes in flock membership. Average lifetime reproductive success (LRS) of males and females was variable and best predicted by lifespan. Male rank history also influenced realized reproductive success. Birds with higher average rank over their lifespan were more likely to reproduce successfully. However, among successful birds, average rank did not significantly predict LRS. Thus, birds that lived longer and attained high social rank earlier had higher fitness, but this effect was not manifested as fine-scale differences among successful individuals. Taken together, these findings demonstrate the importance of social factors influencing individual fitness.

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The authors examined auditory distance perception using a go/no-go operant discrimination task in the laboratory. They taught male black-capped chickadees (Poecile atricapillus) and male zebra finches (Taeniopygia guttata) to discriminate degraded (far) from undegraded (near) versions of male chickadee songs and female zebra finch calls, showing for the 1st time that males can discriminate distance cues in heterospecific vocalizations and in female calls. Chickadees learned faster than zebra finches, and both species learned to discriminate chickadee songs faster than zebra finch calls. Chickadees more than zebra finches attended to amplitude in tests pitting it against other distance cues, demonstrating that amplitude is a potentially useful cue for estimating distance from vocalizations.