Oklahoma Black-capped Vireo dispersal study

Mechanisms driving breeding dispersal are complex but are of high interest
because dispersal strongly links individual fitness to population
dynamics. We examine the relative importance of personal information,
neighborhood effects, and structural habitat characteristics in
determining an individual’s propensity for breeding dispersal. We
attempted to identify relevant cues for breeding dispersal of a North
American territorial migratory bird species, the Black-capped Vireo. We
color marked and radio-tagged males in Southwestern Oklahoma and used a
conditional inference tree analysis to evaluate 11 variables that
individuals could use as predictors of emigration. We used the correlation
between arrival date and habitat structure to determine habitat
preference. Breeding dispersal propensity among Black-capped Vireos
depended mostly on their personal breeding experience, but also on
reproductive information gleaned from their neighbors. Older and younger
age classes that reproduced successfully did not disperse, but younger age
class individuals that failed to reproduce were more likely to disperse
than older individuals within the breeding season. Dispersal events among
young males were significantly related to the proportion of their
neighbors that successfully reproduced with more dispersal from
neighborhoods of fewer, less successful neighbors. Vegetation structure
within a territory was not identified as a significant cue.