I studied a free-living population of white-throated sparrows
(Zonotrichia albicollis) to determine which, among eleven
behavioural, morphological and situational variables, were correlated
with the distance from cover at which individuals fed (a presumed index
of predation risk) and the amount of time they spent feeding at three
observation sites. Time spent feeding was correlated only with
dominance, an indication that dominant birds obtained greater access to
high quality food. In contrast, an assortment of factors affected
distance to cover. Individuals tended to feed far from cover if they
were: (1) in large flocks, (2) males, (3) young and (4) subordinate.
Distance to cover for the population as a whole increased during cold and
cloudy conditions. | |
The failure of dominance alone to determine a bird's distance to cover
probably resulted in part from the confusion caused by dominant
heterospecifics (cardinals, Cardinalis cardinalis) and from their
apparent tendency to tolerate mainly small white-throated sparrows (which
tended to be subordinate) feeding with them.
Overall, this study indicates that while dominance clearly allows easy
access to food, it is only one of several factors affecting exposure to
predators.
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