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To investigate the influence of prior residence on dominance in captive
white-throated sparrows, Zonotrichia albicollis, we studied 28
groups of six birds each in outdoor aviaries during winter. After
periods of prior residence ranging from 2 to 45 days, the three
highest-ranking birds in each of two aviaries were placed together in one
of the aviaries and the three lowest-ranking birds from each aviary were
placed together in the other aviary.
The influence of prior residence increased gradually over at least 2
weeks to an asymptote at which individuals with the advantage of prior
residence dominated newcomers in approximately 90% of cases.
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In the initial groupings of unfamiliar birds, when only intrinsic
features of individuals influenced dominance, only size as indicated by
wing length correlated with dominance. The gradual increase in dominance
of residents over newcomers suggests that prior residence is not used for
conventional settlement of disputes.
This influence of prior residence on dominance provides a mechanism for
the tendency of white-throated sparrows in the field to dominate more
opponents in the centres of their ranges than at the edges.
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Because dominance relationships between strangers in initial groupings in
captivity develop in the absence of the natural contexts for these
interactions, these studies reveal only intrinsic mechanisms of dominance
and thus do not necessarily reveal the mechanisms by which interactions
are settled in natural situations. Experiments on captive individuals
can, however, clarify the causality of correlations observed in the
field.
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The present study has confirmed a possible mechanism for the correlation
between location and dominance in a free-living population of
white-throated sparrows: an individual's residence in a location
gradually increases its ability to win contests with newcomers there.
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